CN1700540A - External resonant cavity semiconductor laser and method for manufacturing same - Google Patents
External resonant cavity semiconductor laser and method for manufacturing same Download PDFInfo
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- CN1700540A CN1700540A CNA2004100903103A CN200410090310A CN1700540A CN 1700540 A CN1700540 A CN 1700540A CN A2004100903103 A CNA2004100903103 A CN A2004100903103A CN 200410090310 A CN200410090310 A CN 200410090310A CN 1700540 A CN1700540 A CN 1700540A
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Abstract
This invention relates to outer resonance chamber single mode laser design, wherein, the short optics path length used in optical resonance chamber provides the single wave choice parts to provide one single mode operation and selective operation mode.
Description
Related application
The application requires in the U.S. Provisional Application No.60/472914 of submission on May 23rd, 2003; The priority of the U.S. Provisional Application No.60/472692 that the U.S. Provisional Application No.60/472873 that on May 23rd, 2003 submitted to and on May 23rd, 2003 submit to is quoted the also full content of the above-mentioned application of reference at this.
Technical field
The present invention relates generally to couple light to the laser of external optical resonant cavity, and The present invention be more particularly directed to a kind ofly can carry out tuning laser diode, it is characterized in that the laser and the external optical resonant cavity that are coupled by from one group of discrete emission wavelength, selecting specific emission wavelength.More specifically, the present invention relates to use in the resonance-cavity laser system outside, to select little processing Fabry-Perot etalon (etalons) of required Laser emission pattern, verified can be used in Wave division multiplexing (WDM) Fiber Optical Communication System.
Background technology
Those Fiber Optical Communication System that generally adopt in Fiber Optical Communication System, for example wireless telecommunications are made up of three primary elements: transmitter/light source, optical fiber link or channel, and detector/receiver.If employing laser-relative with light-emitting diode (LED)-as light source, for data transmission capacity, speed and distance, this system has obtained absolute predominance; And if adopted semiconductor laser diode particularly as the transmitter light source, will be further favourable for cost, compactedness, reliability and power consumption.
Nominally though laser is a monochromatic source, in fact, laser produces several emission wavelengths light of (being called pattern) usually, unless take to suppress the step of all patterns rather than a kind of pattern, laser is called the monotype laser in this case.This monotype laser can provide superior function owing to reduce scattering loss in fibre system, it still has higher data speed and long transmission range.
Just can significantly increase the transmission capacity and the function of optical fiber link by Wave division multiplexing technology (WDM) technology.Usually, multiplexing technique refers to transmit simultaneously several signals or information in same circuits or channel.For example, just realized frequency division multiplex in the coaxial optical fiber system by several Independent Carrier Wave signals are provided, each carrier signal has the characteristic frequency of distribution and modulates each carrier signal with the independent information signal.At the receiving terminal of coaxial cable, the low pass filter of selection separates several carrier frequencies, thus each carrier wave by demodulation to produce the initial information signal.As another example, in digital data transmission system, interweave forming synthetic high speed, thereby realize time division multiplexing than byte stream by byte stream (bit streans) to several signal sources.At receiving terminal, byte stream decomposes with the time frame and the synchronizing signal that are fit to.
In the optical fiber light communication system, adopt the analog multiplexer technology that is called Wave division multiplexing (WDM).WDM transmission the time based on the light signal of distributing to the different carrier wavelength.The several lasers that have emission wavelength discrete and that separate well by several information signal separate modulation.The carrier wavelength that wdm system distributes is called " channel ".The output of the laser of all modulation all is transmitted in the public optical fiber and carries out multichannel at the receiving terminal of link by the filter to wavelength-sensitive and decompose.Therefore, the signal that decomposes according to their carrier wavelength just is coupled to the detector at specific channel wavelength.At present, adopt the optical fiber photosystem of WDM well to set up the basic framework of part wireless telecommunications.
That wavelength division multiplexed systems needs is several at least-reach 50-100 laser transmitter sometimes, and each laser transmitter is worked under different emission wavelengths.Because emission wavelength is the inherent characteristic of conventional laser device to a great extent, so the laser diode that wdm system just need be several or how dissimilar, each laser diode has specific emission wavelength.On the contrary, the wdm system preferred embodiment is only to adopt one type laser, but this laser is easy to modulation and is set to any predetermined emission wavelength operation by the user.This laser is called " tunable ", wherein can adjust emission wavelength according to application-specific and system requirements.In having multi channel WDM fiber optic system, each channellized transmitter should adopt the laser of same type, but its single emission wavelength is by tuning and be set to the wavelength that branch is used in particular channel.In other words, this method is only used one type of tunable laser, and need not many dissimilar monotype lasers with independent emission wavelength, the generally well-known outstanding problem of this method is because it has simplified total amount, configuration, the I﹠ M of wdm system significantly.For example, need not the stock, the many dissimilar lasers of installation and maintenance, but adopt conventional tunable laser to be used for the light source of all transmitters, and select its emission wavelength according to the position of inserting in the wdm system.Use tunable laser repacking wdm system easily, by selecting new emission wavelength, just can easily transmitter be distributed to new channel once more simultaneously.Therefore, the invention provides a kind of mode converting device that realizes compression exterior resonant cavity laser, and simple especially a kind of structure is used for the WDM light communication system, thereby a kind of important progress is provided in the laser technique field.
Summary of the invention
The present invention also provides a kind of exterior resonant cavity semiconductor laser, and it comprises: gain medium is used to provide the light source of light radiation; Be arranged to the exterior light resonant cavity with the gain media optical communication, the size of this resonant cavity is enough short so that allow single wavelength selector spare to select and keep single vertically zlasing mode; And the single wavelength selector spare that externally is provided with in the optical cavity, to select and to keep single vertically zlasing mode.In a kind of required structure, wavelength selector spare comprises little processing criterion tool (etalon).For example, the invention provides a kind of little processing criterion tool, comprising: crystalline substrates with first and second apparent surfaces; The wall that is provided with on the first surface of substrate, this wall have an outer surface; Extend through the through hole of substrate until second surface from first surface, this through hole has the substrate adjacent with the expose portion of wall; And second interferometric filter that on first interferometric filter that is provided with on the outer surface of wall and the expose portion at wall, is provided with, so that an etalon is provided between interferometric filter.
The present invention also provides a kind of method that is used to make little processing criterion tool, comprising: the crystalline substrates with first and second apparent surfaces is provided; Provide wall on the first surface of substrate, this wall has an outer surface; Formation extends through the through hole of substrate until second surface from first surface, and through hole has the substrate adjacent with the expose portion of wall; And provide second interferometric filter providing on the outer surface of wall on first interferometric filter and the expose portion at wall, so that an etalon is provided between interferometric filter.
Description of drawings
Fig. 1 a-1c schematically illustrates the different embodiments of use according to the exterior resonant cavity laser of the etalon as mode filtered light or model selection device of the present invention, comprising: Fig. 1 a has static etalon, Fig. 1 b and has the etalon that tiltable etalon and Fig. 1 c have changeable gap.
Fig. 2 schematically illustrates the conventional criteria tool of being made up of thin layer of dielectric, and its both sides apply with the multilayer dielectricity lamination, and this dielectric stack is as interference reflector.
Fig. 3 shows the exemplary spectrum transmission characteristic of etalon.
Fig. 4 a-4e shows the correlation spectrum characteristic of exterior resonant cavity edge emitter laser, show the situation of short relatively outer optical resonance cavity length and the widely pattern at interval of generation especially, and comprise: 4a is the laser gain bandwidth, 4b is the optical cavity pattern, 4c is the laser emission mode that allows, 4d is the spectral response that is used for the special model selection device of setting, and 4e is the selection laser emission output of the model selection shown in Fig. 4 d.
Fig. 5 a-5h shows the correlation spectrum characteristic of exterior resonant cavity edge emitter laser, show the situation of short relatively outer optical resonance cavity length and the near space pattern of generation especially, and comprise: 5a is the laser gain bandwidth, 5b is the optical cavity pattern, 5c is the laser emission mode that allows, and 5d is the mode filter of minimizing pattern quantity; 5e is the spectral response that is used for the special model selection device of setting with appropriate resolution, 5f is selection laser emission output from the model selection device of Fig. 5 e and the non-selection intentionally that shows adjacent pattern, 5g is used for specific setting to have spectral response with respect to the model selection device of the improvement resolution shown in Fig. 5 e, and 5h is the laser emission output of the model selection shown in Fig. 5 g.
Fig. 6 a schematically illustrates little processing criterion tool of being made up of the substrate with groove, uses the coating groove of the dielectric laminated conformal of multilayer on its both sides.
Fig. 6 b-6h schematically takes off the bright order that is used for the manufacturing step of the little processing criterion tool shown in the shop drawings 6a, comprise: 6b is the substrate that forms wall on it, 6c is the groove that forms in said substrate, 6d is that the multilayer that applies of the conformal that forms on two sides of etalon is dielectric laminated, 6e is used for the through hole that the etching wall forms, 6f is that the etching wall is to form air-gap, 6g is the top view that little processing criterion tool that the area of through hole and wall removes is shown, and 6h is that the application of electrode is to be undertaken tuning by changing air-gap.
Fig. 7 a-7d schematically illustrates by being coated with the dielectric laminated substrate of thin multilayer (7a) on the one side and having inclined-plane depression and be coated with the alternative embodiment of little processing criterion tool that dielectric laminated another substrate (7b) of multilayer forms equally on an one side, by combining structure (7c) that said substrate binding is formed together and form groove (7d) on two sides of said combining structure.
Fig. 8 a has illustrated that simulation illustrates 24-mmFabry-Perot optical cavity pattern.
Fig. 8 b has illustrated that simulation illustrates 12-mmFabry-Perot optical cavity pattern.
Fig. 8 c has illustrated that simulation illustrates the spectral transmissions of little processing criterion tool.
Fig. 8 d describes the spectral transmissions peak value that simulation illustrates little processing criterion tool more in detail.
Fig. 8 e has illustrated that simulation illustrates the spectral transmissions of little processing criterion tool, and wherein the air-gap space is variable, has caused the drift of transmision peak.
Fig. 9 a schematically illustrates the tunable external optical resonance-cavity laser system with mode counting and selective power.
Fig. 9 b schematically illustrate tunable external optical resonance-cavity laser system with mode counting and selective power and device that reference frequency is read so that set up the laser emission mode.
Embodiment
The present invention relates to a kind of design of exterior resonant cavity monotype laser 100, wherein the short optical path length of optical cavity 103 (～3-25mm) provide enough spaces of vertical pattern, allow single wavelength to select element such as little processing criterion tool (etalon) 120 that single mode operation is provided, and can optionally select mode of operation.The total path length of laser optical resonant cavity 103 be between the reflector 108,110 of laser resonant cavity 103 path, normally be included in reflector 110 of coating on the outer polyhedron face of element 102 of emission laser and as the path between the reflector 108 of outer lens.Little processing criterion tool 120 is wave-length sensitive devices, comprises a pair of reflecting surface, and dielectric laminated 202,204 as the thin-film multilayer of being separated by transparent lamina or air-gap 124, it can be used for the light of selectivity transmission or reflection specific wavelength.Therefore, etalon 120 is used for preferentially suppressing or keeping the zlasing mode of optical cavity 103.
Exterior resonant cavity laser 100 is configured so that cooperate with etalon 120, so that the switched laser device is exported between little processing criterion tool 120 several or multiple discrete wavelength emission pattern that can limit in the total path-length by laser optical resonant cavity 103.Tunable etalon 120 promptly can incide the angle of the light on the etalon, for example make etalon 120 tilt to revise its relevant transmission characteristic of wavelength by change.Alternately, etalon can be designed to the space of variable air gap, and this space can be regulated by the etalon slit that changes between the multilayer dielectric laminated 202,204.For example, etalon 120 can be undertaken tuning by the voltage control signal that is applied to the electrode that forms on the etalon 120, so that change the air-gap space.Undersized little processing criterion tool 120 just allows relatively to reduce the external optical cavity length, then can produce the more lasing mode of wide interval, makes model selection be more prone to finish by the etalon of simple designs.Because mode spacing is wideer, has just reduced the optical filtering demand (passband width needn't be too narrow) on the etalon 120.Therefore further easily use the little processing criterion tool that lasing mode is selected that is used for disclosed here.
The present invention also relates to a kind of element of wavelength can being selected and is used for discrete pattern transition between the vertical pattern of laser resonant cavity 103, therefore allow from benchmark or " this locality " wavelength counting to excite and unactivated state between the equally simple device of transition so that determine the variation of operation wavelength.
Now, with reference to the accompanying drawings, wherein similar elements is labeled as identical numeral, and three exemplary configurations of the present invention have been shown in Figure 1A-1C especially.External optical resonance-cavity laser 100 is set, and it comprises along the optical element and the photoelectric cell of common optical axis A-A ' distribution.Light source comprises the element 102 of launching laser, and it can be to show the gain of light, for example limit the combination that is of value to the optical gain material/medium or the optical material of excitation luminescence under waveguide mode or the cavity modes at light.For example, the element 102 of emission laser can comprise the edge-emission semiconductor diode laser under the bias voltage that is used for the WDM fibre system.Also can adopt the laser of other type, for example comprise the surface-emitting type laser of vertical cavity surface emitting lasers (VCSEL).The laser medium that is fit to can comprise various kinds of compound semiconductors, and this compound semiconductor comprises the alloy of InP, GaAs and InAs.The element 102 of emission laser vertically couples light to external optical resonant cavity 105 along optical axis A-A '.The length sum of the length of laser diode 102 and exterior resonant cavity 105 defines total optical cavity length 103.This optical path length has been determined the space of vertical pattern, if by determining optical path length along the physical path length of the A-A ' of each physical component and the long-pending sum of the effective emission ratio under its relevant wavelength.If the coefficient the when slit between each element also is included in for air or optical package has consumed this space in addition is in～1.0 the calculated value.Limit the element 102 of launching laser by first end surface 104 and the second end surface 106 perpendicular to optical axis A-A '.If the element 102 of emission laser is formed on the single crystal samples, end surface 104 just can be by forming crystal-cut with 106 with smooth, the parallel surface that exposure is called the edge facet so.
Optical axis A-A ' locates and two reflectors 110,108 of element 102 that emission laser wherein is set form optical cavity 103 by being positioned at.Optical cavity 103 comprises the interior resonance cavity segment and the exterior resonant cavity part 105 of the element 102 of launching laser.Terminal reflector 108 can be the outside speculum separately of the element 102 of emission laser, to limit an end of resonant cavity.Wish the plane of ground orientation reflector 108, so that it is perpendicular to Standard shafts A-A '.Another end of relative with this end optical cavity that is limited by reflector 108 limits by the reflector of the reflectance coating 110 that is set to form on the first surface 104 of the element 102 of emission laser.The second surface 106 that is the laser diode of edge facet equally can apply with antireflecting coating 112, so that prevent reflection, so that between first and second end surfaces 104,106 of the element 102 of launching laser, can not provide resonant cavity at second surface 106 places.
In the operation, thus the injection by the minority carrier in the p-n junction or by the absorption electronics pumping of light or pump laser medium optically, its any non-equilibrium distribution that all causes electric charge carrier.In the case, laser material just shows the gain of light, thereby the absorption of photon has just caused the stimulated emission of photon in determining the spectrum gain bandwidth range.Emission laser is that ballistic phonon has limited some photons by reflector 108 and reflector 110 within optical cavity 103 owing to the compound result of the excess charge carriers relevant with non-equilibrium condition.A this radiative part has has determined wavelength and the direction of propagation (being generically and collectively referred to as pattern), provides enough feedbacks with the constructive interference of reason optical cavity 103, has therefore kept zlasing mode.In fact, reflectance coating 110 reflections and not obvious, so that the coating 110 that the part photon that produces by stimulated emission passes outside end surface 104 and the optical cavity 103 is transmitted.This light has just constituted Laser Output Beam 114.Can adopt other structure of known exterior resonant cavity laser, for example two surfaces of the element 102 of semiconductor emission laser can be the AR coatings and adopt two external mirrors, alternately, the facet lens can reflect the light of the overwhelming majority, and outer lens 108 can be exported from system, coupled with less reflector.
Because optical cavity 103 supports that usually multi-mode and laser have the finite gain bandwidth, laser 100 will be launched the light of several wavelength.Decided the multi-mode laser device emission wavelength of permission by effective optical length of resonant cavity 103: when reducing optical cavity length, laser 100 just demonstrates the emission wavelength pattern of less more wide interval.The optical cavity pattern is as end of facet coating 110 with as the pattern of the total optical cavity length between the reflector on another end of exterior resonant cavity speculum 108 108,110.Therefore, the optical cavity pattern comprises the stack of the optical path length of the optical path length 103 of the element 102 of launching laser and exterior resonant cavity 105.Use for WDM, it is used for Laser emission is reduced to single-mode, and further has the ability of selecting specific single transmit pattern.
External optical resonant cavity 105 can comprise other optical element, for example lens 116, so that be enough to calibrate or focus on light from semiconductor Laser device, make it pass etalon 120 propagate, from reflector 108 reflections and turn back to the element 102 of emission laser with the low-loss that is fit to that allows laser operation to obtain clean laser gain.Can obtain another kind of structure, for example be used for the combination of concavees lens or the lens and the recessed speculum of reflector 108.Additional selectable unit can comprise filter, grating, prism etc.Still can outside optical cavity 103, place other optical element, for example, the collimator lens 118 of correcting laser output.
For example, Fig. 1 a show according in the externally optical resonator of the present invention along little processing criterion tool 120 of optical axis A-A ' setting.Little processing criterion tool 120 is used to eliminate the subclass (subset) of admissible lasing mode.In fact, little processing criterion tool 120 has been upset the resonance condition of some optical cavity patterns, and these patterns are characterised in that etalon 120 does not transmit the wavelength that is used for resonance condition.And kept pattern with little processing criterion tool 120 transmissible wavelength.Wish that little processing criterion tool 120 constitutes single (selection) laser resonant cavity mode producing resonance of only permission, this structure can be made by manufacturing process of the present invention proposed below.
Get back to model selection of the present invention aspect, as shown in Fig. 1 b, little processing criterion tool 120 can tilt, revise incidence angle thus and revise its spectral transmissions characteristic with respect to cavity modes thus, the result can change the pattern of selecting in order to keep the emission laser operations (or a plurality of pattern).Selectively, Fig. 1 c has illustrated: little processing criterion tool 120 can comprise the air-gap or the vacuum crack 124 that can change with the spectral transmissions characteristic of revising little processing criterion tool 120, and by air-gap or vacuum crack 124 just can selective light resonant cavity 103 the particular laser pattern.
By detailed description thus, exterior resonant cavity laser 100 can play the function of light source, and the user utilizes it just can select single, narrow emission wavelength from the numerous suitable discrete emission wavelength bandwidth that is mainly limited by cavity length.
According to the present invention, because optical cavity 103 has relatively shorter optical path length, so that vertical pattern is spaced apart relatively widely, therefore the element complexity of tunable laser 110 is reduced substantially.Successively, just can utilize the relatively simple for example little processing criterion tool 120 of wavelength recognition means to realize utilizing laser tuning of model selection output, for example, little processing criterion tool can comprise than typical interferometric filter dielectric layer relatively still less.And, because short external optical cavity length, by selecting and filtering just can be exempted common auxiliary element and the device of finding than the simplification that the emission wavelength of wide interval provides in traditional WDM Optical Maser System.For example, typical tunable laser needs the feedback mechanism of several complexity usually, this mechanism comprises that piezoelectricity can adjust cavity length, hot fine setting and adjustable grating or other filter, and wherein each all has the information of providing so that keep the control ring of single given frequency.The invention provides simple more feedback mechanism, for example, if the temperature of fixed system, so just can know enough accurate vertical pattern position, by in from the vertical pattern to the vertical pattern, strictly calculate the quantity of saltus step, just can easily make the required pattern of tuned element selection by the modulation in the luminous power of stand-by period observation.
Now, get back to the etalon structure, the schematic diagram of etalon 102 has been shown among Fig. 2.Etalon 102 comprises that a pair of reflective film is dielectric laminated 202,204, by size d
0The thin slice of transparent material 206 or the air-gap of insertion or the slit that is filled with gas material separate this dielectric laminated 202,204.The thin metallization dielectric reflector of the 1/4 wavelength thickness layer that lamination 202,204 expression replaces based on high coefficient material and low coefficient material or required broadband dielectric reflector.The centre wavelength that designs for dielectric reflector should typically be chosen as the center of the required scope of next-door neighbour's laser works frequency.The wavelength recognition capability of etalon 102 improves with the number of plies of inserting in multilayer is dielectric laminated.In each lamination 202,204, according to required, the number of layer can reach 50 or more.
According to incident light wavelength and incidence angle θ, etalon 120 will reflect or transmit the incident ray of high-contrast.This effect can be by transmitting definite wave-length coverage and reflecting other wave-length coverage to be used to select the wavelength of incident ray.The typical transmission spectrum of etalon 120 has been shown among Fig. 3.The width and the difference between transmision peak 302 and reflection baseline 304 of wavelength separated and transmission bandwidth can be made as the particular demands that satisfies given application.Can accurately simulate the transmission characteristic of little processing criterion tool 120, and be easy to make design optimization based on computer simulation.Can by several modes realize little processing criterion tool 120 tuning, promptly change the wavelength dependency of the transmision peak of Fig. 3.Can change the interval d between dielectric laminated
0Under the situation of the etalon with air-gap, as shown in Fig. 1 C, this can realize by the separation distance that changes air-gap.The second tuning method is the inclined light shaft etalon 120 with respect to light beam, and this method has changed incidence angle and correspondingly revised the transmission of the light beam that passes little processing criterion tool 120.The tuning another kind of method of etalon is to use the material of the reflection coefficient that can change it for example to come blind 206 by applying electric field.
Now, get back to the operation of exterior resonant cavity laser 100, total resonant cavity optical path length illustrates the performance of the laser 100 of remarkable calculating.Effective optical path length λ of device
EffMay be defined as:
Here, d
iAnd n
iBe thickness and the refractive index that comprises the element of device.
With regard to etalon 120, this just requires the refraction coefficient n to each dielectric laminated element layer i
iWith layer thickness d
iProduct and comprise the transparent sheet in each slit between the physical component or the refraction coefficient n of air
0(n=1) and the thickness d of thin slice or air-gap (or many air-gaps)
0Product summation.In the case, employing gel or encapsulation come the space between the packing elements, adopt the refraction coefficient of this material to replace n=1 then.Explanation in further detail is for by having two dielectric laminated etalons of forming that add up to the N layer, effective optical path length λ of etalon 120
Eta, effMay be defined as:
Also will make an explanation about the present invention, and exist and reduce the motivation of this optical path length better, and can implement by micro-machined little processing criterion tool 120 of the present invention.
Total optical path length λ of optical cavity 103
Cav, effDetermined the mode spacing of laser.For nominal emission wavelength lambda
0, the wavelength interval Δ λ between the adjacent transmission pattern roughly is given as:
Therefore, shorten the optical cavity length lambda
Cav, effValue, just produced the more pattern of wide interval, promptly Δ λ increases.Mode spacing proposes the method for model selection and device restriction and satisfies, and wherein the laser emission mode of tight spacing need have more the model selection of high spectral resolution.
About the present invention and with reference to Fig. 1 a-1c, the effective length λ of optical cavity
Cav, effFor:
λ
cav，eff＝d
las·n
las+d
1+d
lens·n
lens+d
2+λ
eta，eff+d
3
Here d
LasBe the laser length of between first and second end surfaces 104,106 of the element 102 of launching laser, measuring, n
LasBe the refraction coefficient of laser material, d
LensBe the thickness of the lens 116 on the optical axis, and n
LensIt is the refraction coefficient of lens.Lens (or poly-lens) and etalon (or many etalons) by using little machine component just can make effective optical cavity length keep very for a short time.By the method, micro element and system, except the integrated attraction of their compact systems, also provide the wider of the mode spacing that changes exterior resonant cavity laser 100.
Fig. 4 A-4C and Fig. 5 A-5H illustrated the optical cavity pattern the interval and with the relation of laser tuning.Fig. 4 a shows the gain spectra 402 of semiconductor laser 102.The photo emissions laser that is produced by radiation transistion under the wavelength within the gain spectra 402, if the light feedback is provided, the internal gain of launching the medium of laser so just surpasses the loss of light.The optical path of the element 102 of considering and launching laser related, optical cavity 103 provides this feedback, so that suppress to have discrete setting or " pectination " of the wavelength mode 404 (Fig. 4 b) of mode spacing Δ λ.The optical cavity pattern 404 overlapping with the gain bandwidth 402 of laser 102 determined the resonance-cavity laser emission wavelength.Fig. 4 c has provided the output spectrum of exterior resonant cavity laser 100, and this output spectrum is the convolution (convolution) of the spectrum of Fig. 4 a and 4b.The solid line of Fig. 4 d shows for example transmission band spectral response 403 of the little processing criterion tool 120 among Fig. 1 of etalon, its as suppress except that an emission mode all emission modes, and thus the monotype laser of generation as shown in Fig. 4 e export 405.Should be noted that and wish that Free Spectral Range (FSR) is that wavelength is discerned distance between the transmision peak 403 of little processing criterion tool 120 greater than the gain bandwidth (as shown in Fig. 4 a) of laser, perhaps will keep more than one zlasing mode.By identical mark, definite bandwidth that the half range value (FWHM) of the full duration by little processing criterion tool 120 is measured just must be enough narrow, to avoid selecting the adjacent lasing mode of supporting by optical cavity 103 401, if with respect to required operator scheme, adjacent lasing mode 401 will take place to produce the selection gain of required mode in the bandwidth that can not obtain to be enough to suppression mode 401 so.When side mode suppression ratio and acceptable value dependence application, just can measure the power ratio between required mode and the side pattern.Use for many WDM, they are to 45dB from 20.
In addition, as the explanation among reference Figure 1B and the 1C,, just the transmission passband of little processing criterion tool 120 can be converted to new wave-length coverage by little processing criterion tool 120 or the adjustment gap length of tilting.For example, this conversion represented by the dotted line 403a among Fig. 4 d, wherein selects just to have produced the laser emission output that is converted to corresponding emission wavelength 403a (dotted line among Fig. 4 e) under the situation of different mode of laser 100.Under this mode, Optical Maser System can be tuning discontinuously, wherein can select wavelength obvious, good separation among the stable emission wavelength group of distributing to the WDM channel of better qualification.Should be noted that temperature stabilization that need be to a certain degree and determine stable temperature by the permission conversion of possible operation pattern.The conversion that allows depends on channel spacing and is different from CWDM and DWDM, and narrow also different according to grating.For example, the dwdm system typical case of channel need be than the more stable operative wavelength of dwdm system that distributes 200GHz at interval to distribute 50GHz.Temperature drift is mainly determined by the variation of temperature coefficient of the element 102 of emission laser, follows the optical element that adopts in system, and the variation of temperature coefficient changes along the physical length of the temperature substrate (CTE) of assembling element on it.Can adopt the whole bag of tricks of the wavelength pectination that does not heat, for example on low CTE substrate-based, set up, insert the compensating element, that low dN/dT optical element or insertion have negative dN/dT or negative CTE.If surpass the temperature control limit, for example,, so just can at random adopt the technology of this structure for required application just needs thermoelectric (al) cooler.
From the embodiment that describes about Fig. 4, showed to be used to have the needs of enough spectral resolutions with the etalon of selection single resonance cavity laser pattern.As the embodiment of a correspondence, Fig. 5 shows has the exterior resonant cavity laser of the emission mode of tight spacing more.Because mode spacing roughly is inversely proportional to cavity length, when increasing, the length from exterior resonant cavity shown in Figure 4 105 just realized compact more pattern.By the result that the cavity modes that is allowed with Fig. 4 b and Fig. 5 b compares, the exterior light resonant cavity 105 that has above the length of Fig. 4 is suitable for showing the pattern of tight spacing more.When cavity modes is compact more, promptly reduce Δ λ, etalon 120 just must have bigger recognition capability, and promptly significantly reduced FWHM is not so that be not intended to select adjacent pattern when the select target pattern.More concisely, the etalon transmission response 503 with FWHM wideer than optical cavity mode spacing will select to surpass one pattern, by solid line output emission peak 502 and 504 expressions of Fig. 5 f.Similarly, when etalon transmission band 503a is converted to when selecting another kind of lasing mode, will select the adjacent peak value that adds unintentionally, by two dotted line lasers output peak values 506 and 508 expressions of Fig. 5 f.Should proofread and correct this problem by the employing etalon that to have big identity be narrow FWHM, understand narrow FWHM by the ideal standard tool with the transmission bandwidth spectral response shown in Fig. 5 g, it has realized the monotype laser output shown in Fig. 5 h.As previously described, the FSR of wavelength selector also must be greater than the gain bandwidth of laser, to avoid selecting to surpass a kind of pattern that can not discern application.
Another purpose that solves the tight spacing pattern is for the purpose of removing mode subset, interferometric filter, etalon or similar wavelength recognition means is inserted in the exterior light resonant cavity 105.As a result, therefore realized the little density pectination of cavity modes.Fig. 5 d shows the interferometric filter passband response of decay, for example, and each other cavity modes.Add ons can reduce the resolution requirements of wavelength recognition mode selector, but under the tangible situation of additional complexity, in order to allow enough spaces to insert resonant cavity, also should need to increase the exterior light cavity length.The invention provides and obtain to have enough resolution with the ability of the tunable etalon of selecting single lasing mode and the etalon of the external optical cavity that do not need to extend, so that be fit to bigger or additional model selection element (by producing tight space pattern more, having aggravated the model resolution problem thus).
It is tuning that another aspect of effective optical path length of relevant laser emission mode relates to etalon.Tilt little processing criterion tool 120 technology or change its clearance distance d
0So that revise the spectral transmissions characteristic that it is used to change effective optical path length of exterior resonant cavity 105.As a result, the laser emission wavelength also can change.Ideally, in order to stablize emission mode spectrum, this effect will be minimized, and will the debase the standard importance of effect of the tuning effective optical path length to external cavity 105 of tool of the design standard that is used for little processing criterion tool 120.This just inserts air-gap by design easily and comes the solid dielectric in the alternate standard tool 120 to realize, because slit 124 comprises the essential part of the optical path of etalon, when inclination etalon 120, slit 124 can not change total resonant cavity path thus.Can at random FEEDBACK CONTROL, additional wavelength locking etalon or how much adjustment be introduced so that improve these disturbing influences.
The present invention brings several key characters for the etalon 120 that is used for tuning outer laser.The first, can make little processing criterion tool 120 by micro-processing method, little thus processing criterion tool 120 relative compact and the assembling of compatible micro-optic.The second, can be used for tuning little processing criterion tool 120 by electromechanical, wherein voltage signal is modulated the transmission characteristic of little processing criterion tool 120.The 3rd, by comparing with the conventional criteria tool, the optical path length of little processing criterion tool 120 is less relatively.The 4th, by comparing, little with the change effect of tuning total resonant cavity optical path length to little processing criterion tool 120 with the conventional criteria tool.These features below are discussed, in the model selection that is applied to the exterior resonant cavity laser, are adopted these features to have remarkable advantage.
According to the present invention, wish that but little processing Fabry-Perot etalon 120 has high accuracy reproduction optical transmission characteristic and compactness, in addition, provide some functions so that the spectral transmissions characteristic of tuning little processing criterion tool 120 consequently can realize the lasing mode selection.Wish that the tuning of little processing criterion tool 120 is under the electric control.Conclusion, the transmission characteristic of modulating little processing criterion tool 120 for example by one or more electromechanical effects, the result is exactly the function that applies voltage at the wavelength of the center of the transmission passband (or many passbands) of tunable little processing criterion tool 120.
Fig. 6 a shows the sign an undertaking profile of structure 600 of a kind of specific criteria according to the present invention.Can be in flat board or substrate 602 manufacturer's standard tool 600, for example conventional silicon wafer that adopts of typical case in microelectronics industry.Can in a side of substrate 602, form groove 604 with sloped sidewall 605.This ad hoc structure is＜100 by the wet method anisotropic etching〉the typical resonance chamber of making in the silicon, etching here stops at etching stopping layer for example on silica or the heavily doped silicon.Can adopt another kind of engraving method, for example deep reactive ion corrosion.The side that wherein forms the substrate 602 of groove 604 will be called " back side " 606 of etalon.On a side of the substrate 602 relative, form wall 608 by the made that is different from substrate 602 with groove 604.The outer surface of wall 608 will be called etalon 600 " front surface " 607.The plural layers lamination 612,614 of dielectric coating is the front surface and the back side 607,606 of coverage criteria tool respectively.The leading flank coating 612 that forms on the flat front of substrate 602 is very smooth.Back coating 614 is the conformal and even recess sidewall 605, substrate 603 and the back side 606 of covering.Can between dielectric laminated 612,614 air-gap 616 be set two of place-centric on the groove 604.Can produce air-gap 616 by the etch-hole etching wall 608 that in top dielectric lamination 612, forms.The order of multilayer dielectric coating 612,614 quantity according to each layer, each layer, the refraction coefficient of each layer and the thickness of each layer constitute, so that play dielectric reflector, for example as thin film optical components well known in the art and as conventional reflection and the antireflecting coating of making that adopt on optical element.For example, coating 612,614 can be made up of the alternating layer of silicon dioxide (about 1.46 refraction coefficients) and silicon nitride (about 2.0 refraction coefficients).The optical thickness of the element layer of interferometric filter (that is, actual physics thickness multiply by be concerned about the refraction coefficient of the material layer under the wavelength) can be fabricated to quarter-wave or its multiple corresponding to the laser emission wavelength.Can be in same technology dielectric coating and back side dielectric coating 612,614 before the deposit so that leading flank coating and back coating 612,614 have very close same optical properties and transmission characteristic.The appropriate methodology of deposit dielectric layer comprises thermal evaporation, electron beam evaporation, sputtering deposit and chemical vapor deposition.Chemical vapor deposition (CVD) comprises low pressure chemical vapor deposition and plasma enhanced CVD because they be conformal and be used for simultaneously deposit Front-coating mirror and back coating 612,614, so atomic layer deposition is to attract photon.Should find out the essential characteristic that the structure of little processing criterion tool 120 of Fig. 6 a has been showed the etalon shown in Fig. 2, two interferometric filters of slice separates by air-gap or transparent material in other words.
Now, get back to the manufacturing of etalon 600, the present invention also provides a kind of method of manufacturer's standard tool 600, and the order of step has been described among Fig. 6 b-6h.Fig. 6 a-6f and Fig. 6 h are profiles, and Fig. 6 g is a top view.Be to be understood that, technical descriptioon described here a kind of order of step, sequence of steps can adopt on demand sets up and uses conventional micro-processing technology, but those of ordinary skills should be understood that, the various variations of these steps and also can make the various replacements of these steps and to have the structure of identical characteristics and function in fact.
In Fig. 6 b, in for example deposit or otherwise form layer of spacer material 608 on the silicon wafer of substrate 602.Because its smooth surface and the smooth and etched characteristic of may command, the silicon single crystal wafer that has polished on two sides is the better selection of substrate 602.Other suitable substrate comprises the semiconductor wafer of glass, pottery, fusion silicon dioxide, quartz or other type.Typically, silicon substrate 602 has about 0.5 millimeter thickness, and wall 608 has 2 microns to 30 microns thickness range.Selectively, substrate 602 can be insulator silicon (SOI) structure, and this insulator silicon (SOI) structure has the embedding silicon dioxide layer of the 0.1-2 micron thickness that the silicon wafer that ∽ 0.5mm is thick separates with the silicon layer of deposit 2-30 micron thickness.Should be noted that substrate needn't be transparent to laser wavelength, because all backing materials have just been removed in the formation of groove 604 from the optical path of laser beam.The basic principle that material is selected is that backing material can be by the selectivity etching with respect to material spacer layer.This demand is satisfied in the combination of many materials, the combination of many materials be included in as substrate 602 do not mix or lightly doped silicon substrate on the boron-doping of deposit or other impurity that mixes silicon wall 608 or on Sapphire Substrate 602 deposit silicon wall 608.In the previous case, doping wall 608 can be resisted it otherwise is used etched the doping or the etching of lightly doped silicon.
In the embodiment of an expectation, substrate 602 can be a silicon single crystal wafer, and interval insulant 608 is the silicon of heavy doping boron.Can enter the silicon layer 608 that silicon wafer 602 forms doped with boron by the epitaxial growth or the ion injection of doped with boron layer.
As shown in Fig. 6 c, can etch the groove 604 that passes substrate 602 according to the form of passing substrate 602 formation bellmouths, substrate 602 has wall 608, with wall 608 as the barrier layer that stops etching (or oxide provides etching to stop, and this oxide contacts with wall under the SOI silicon wafer situation).For example under the situation of (100) silicon, can adopt potassium hydroxide (KOH) solution as the anisotropic etching agent, at silicon substrate 602 so that the sidewall taper of groove 604 to be provided.Other etchant that can be used for this purpose comprises hydrazine and EDP (the burnt catechol of ethylenediamine).And, when be in the typical case have other backing material for example the pottery situation the time, can also adopt isotropic etchant.The characteristic of required etchant is that it removes backing material quickly than material spacer layer.Selectively, under the situation of SOI wafer, need the selectivity of etchant with respect to buried oxide layer.The representative diameter of the groove 604 at wall 608 places is the 100-500 micron, although this size can be fully according to use and optical cavity 103 in the thin narrow portion size of light beam of element 102 of emission laser change.
As shown in Fig. 6 d, it is dielectric laminated 612 to form plural layers on the front surface 607 of substrate, and this dielectric laminated 612 forms optical interference filters, and forms dielectric laminated 614 on the back side 606 of substrate.Design the sandwich construction that also deposit has staggered high index of refraction and low refraction coefficient and quarter-wave thickness according to the method that in Film Optics, extensively adopts.Each layer can or comprise metal oxide and other dielectric substance of the semiconductor of broad stopband width such as gallium nitride or carborundum is formed by for example silicon dioxide, silicon nitride.According to the quantity of layer and the centre wavelength of design, the typical gross thickness that the front side is dielectric laminated or the back side is dielectric laminated can be the 2-15 micron.
As shown in Fig. 6 e, in preceding dielectric laminated 612, can form one group of through hole 618.Wall 608 below through hole exposes makes wall 608 be easy to carry out etching.Can be by coming limited hole 618 in conjunction with the photoetching of wet method or dry etching (for example, reactive ion etching) or by other method of for example laser drill.Through hole 618 can be positioned on the groove 604, or around groove 604 and on substrate 602.Typical through-hole diameter can be the 10-50 micron.As shown in Fig. 6 f, trafficability characteristic is carved and is removed the part that is located immediately at the wall 608 on the groove 604, keep air-gap 616 between the front side dielectric laminated 612 and the back side dielectric laminated 614, and wherein air-gap 616 is aimed at groove 604.
The described etching of wall 608 is easy to use the different materials combination that is used for substrate 602 and wall 608 and is easy to the etchant that uses big molecular formula to represent.For example, if wall 608 is that unadulterated silicon or the silicon of boron-doping and substrate 602 are silicon, so just can use xenon difluoride etching wall 608.When substrate 602 usefulness dielectric layers when for example nitride and oxide cover, the easy isotropic etching silicon of xenon difluoride gas, but it is injury-free to keep substrate 602.Can also adopt liquid etchant.Though some slight etching of substrate 602 can be stood, etchant should be significantly etching dielectric laminated 612,614 or make dielectric laminated 612,614 to become coarse.Since the part of etching wall 608, the part of the front side dielectric laminated 612 that just on air-gap 616, suspends.
The top view of the exemplary via hole image that is used for etching wall 608 has been shown, as the situation of 8 through holes 618 arranging around square-shaped patterns among Fig. 6 g.The dashed rectangle of Fig. 6 f shows the approximate range of area, digs the slit 616 of digging out by etching herein from wall 608 two parallel dielectric laminated reflectors 612,614 are separated.In Fig. 6 g, also roughly corresponding to the top view of part front side thin film dielectric lamination 612, this part of dielectric laminated 612 is suspended on the air-gap 616 and by 620 among Fig. 6 f to be represented dashed rectangle.This zone as the optical function of etalon 600 part, the optical interference effect of laser beam is provided.Around the not etch substrate of groove 604 part (promptly, zone outside the rectangular broken line zone in the top view of Fig. 6 g, or corresponding to the substrate part of (622) in the profile of Fig. 6 f expression) give the mechanical stability of etalon 600, and be used in easy to operate and installation code tool 600 in optical cavity 103.Substrate 602 also supports installs and aims at reference surface to be convenient to the accurate location and the orientation of etalon 600.Because the geometry designs of little processing criterion tool 600, the body portion of representing around the part 622 of groove 604 with respect to substrate 602 does not work to the optical path length of etalon 600.In this design, the clean stress that coating needs should be controlled with typical required little clean tensile stress.
Etalon 600 can be provided with additional structure so that allow the tuning of it.The etalon 600 of having represented static excitation in the profile of Fig. 6 h forms conductive electrode 624 on preceding dielectric laminated regional 620 the outside, it is suspended on the air-gap 616.This electrode group is a public electrode, promptly is electrically connected.If substrate 602 is enough to conduction, it just can be used as opposite electrode so.Selectively, the form of for example forming with second conductive welding disk, deposit opposite electrode 626 on as the outer surface at the back side of opposite electrode 626 dielectric laminated 614 by tin indium oxide (ITO).It is transparent advantage that tin oxide and ITO have under the applied wavelength of the optical-fibre communications of being, has avoided the fuzzy of optical path thus.The voltage that applies between electrode 624 and opposite electrode 626 (or a plurality of opposite electrode) provides and stretches or resist dielectric laminated 620 the electrostatic force that suspends, and changes the interval of the air-gap 616 between dielectric laminated 614 and 620 thus.This has just changed the transmission characteristic of etalon 600, especially, makes the wave length shift of narrow transmission band (among Fig. 3 shown in 302).Therefore, this etalon structure provides the tuning of transmission band, and the result provides wavelength tuning by the signal of telecommunication that applies thus.
The alternative embodiment of the etalon 700 of the little processing criterion tool 120 that is used for exterior resonant cavity laser 100 has been shown among Fig. 7 d, and Fig. 7 a-7d shows the exemplary series of its manufacturing step.Fig. 7 a shows and form dielectric laminated 704 substrate 702 on an one side 703.Dielectric laminated 704 can be on the structure, on the component, be similar on the function about describe among Fig. 6 dielectric laminated 612,614.Fig. 7 b shows separate substrate 706, and by mask and control etching or boring, form shallow depression 708 in a side of substrate, and the same side 705 of substrate conformally has been coated with dielectric laminated 710 in separate substrate 706.As shown in Fig. 7 c, aim at and install two substrates 702,706 or two substrates 702,706 are bonded together, so that cave in and 708 be provided on two sides by dielectric laminated 704 and the inner space or the air-gap 712 of 710 bondings.As shown in Fig. 7 c, this structure provides the etalon 700 with air-gap space d.As shown in Fig. 7 d, remove the part of two substrates 702,706, to form the groove of aiming at 714 and 716, its nothing of having showed two bonding air-gaps 712 supports dielectric laminated 718 and 720.As about the explanation among Fig. 6 g, can be applied to not have with the electrode of conductive welding disk or conductive oxide form membrane and support dielectric laminatedly, this nothings support is dielectric laminated to be used for the tuning of static excitation and electric control etalon slit 712.
Embodiment
Notable feature of the present invention is the compact of little processing criterion tool and is easy to optimize more the more straightforward procedure of mode spacing and model selection with the optical path length of the optical cavity 103 of corresponding shortening.Further example goes out of the present invention aspect these in drag and simulation embodiment.
Effectively total light that Fig. 8 a shows in the spectral region of 1550nm wavelengths centered, be used for 24mm is humorous according to cavity length l
Cav, effThe calculating comb shape of longitudinal wave long pattern.Mode spacing is about 0.5nm.Fig. 8 b shows the result that similar simulation foreshortens to total optical path length of laser resonant cavity 12mm.Can expect that mode spacing is increased to about 1nm from the mode spacing of first embodiment.Fig. 8 a and 8b have illustrated the effect of optical cavity length to mode spacing, and the optical cavity of weak point causes wideer interval mode, just need the solution demand of less harshness for wavelength identification, model selection device.
Fig. 8 c (rough indication) and Fig. 8 d (more describing in detail bright) show the calculating spectral transmissions of etalon, etalon is by two dielectric laminated compositions of 5.8 microns air-gap separation, dielectric laminated is 20 layers of alternating layer of silicon nitride and silicon dioxide, every layer is quarter-wave thickness (=λ/4n, here λ=1550nm, n is the refraction coefficient that is applicable to silicon dioxide or silicon nitride).The FWHM of transmission passband is about 0.3nm.The FSR of this etalon (Free Spectral Range), be that wavelength interval between the adjacent transmission passband peak value is about 90nm.This FSR obviously greater than the gain bandwidth of typical 1550-nm wavelength emission laser, surpasses a kind of zlasing mode in order to prevent to keep, and has stipulated this requirement in the relevant discussion among Fig. 4 and Fig. 5.In addition, the resolution of exemplary little processing criterion tool is suitable for solving the adjacent peak value under the long optical cavity situation of 12-mm.Seen in Fig. 8 d, there is about 15dB decay in the pattern within the 1nm of peak transmission.All these embodiment are that single band amounts to calculation, and bilateral has increased the decay of being with between leading in fact.Decay required under the given application will rely on various variablees, comprise the gain curve of laser diode to be used.The inhibition that obtains is easy to adjust by the quantity that increases or reduce dielectric reflector.
The electromotive force tuning capability of the above-mentioned etalon of regulating with reference to the slit is expressed as three spectral transmissions curves shown in Fig. 8 e.With the increment of 8nm, shorten 5.8 microns air-gap, the appreciable drift that has produced transmision peak is to foreshorten to the wavelength shown in curve 802,804 and 806 respectively.Curve 802 is the etalons that are used to have 5.820 micron gap.Curve 804 is to be used for foreshortening to 5.812 microns slit by 8nm, and curve 806 is to be used for further foreshortening to 5.804 microns slit.Therefore, simulation shows the correction of appropriateness relatively of air-gap, thereby be easy to obtain by the static excitation effect, producing useful wavelength identification for 1 micron mode spacing, this mode spacing appears in the optical cavity 103 of the effective optical length with 12mm.Angle by the 1-35 degree little processing criterion tool 120 that tilts will obtain the similar correction of transmission characteristic.
In a specific embodiment of the present invention, be to the material impact of optical path length:
I, has physical length d
LasThe edge emitter laser 102 of=250 microns and about 850 microns optical length.
Ii, 400 micron diameters, make and have a spherical lens 116 that the antireflection of about 720 microns optical path length applies by Spinel.
Iii, for example, the tunable etalon of being made up of the silicon nitride and the silicon dioxide of 10-20 layer 120 is by the frame supported that forms outside the outer peripheral areas that forms the wafer in the etalon 120 as shown in Fig. 6 g.As a result, the etalon optical path length is about 500 microns, and should be noted that this thickness is based on the space that allows to insert the silicon wafer that wherein forms etalon 120.When laser beam path was limited to the groove that forms in silicon substrate, optical path did not increase by the transmission of passing silicon.
Generally, the space between these three elements (element 102, etalon 120 and the lens 116 of emission laser) can manufacture less than 1 millimeter.
Suppose that these optical paths are as follows: millimeter (gap space)=～3, micron (etalon)+1, micron (lens)+515,850 microns (laser)+720 millimeter have provided about 3 millimeters minimum total optical path length.Therefore, according to required pectination at interval, just can be set to have looser or open interval by element.
The present invention also provides by with the output of light detector monitors laser, uses the simple and accurate control laser of the tunable etalon of little processing reflection wavelength, schematically shows an one exemplary embodiment among Fig. 9 a.System shown in Fig. 9 a comprises laser 902, collimator lens 904, and the height reflection of lens 906 and qualification optical cavity 910 therebetween applies facet 908.By the facet 908 transmission laser beam outputs 912 that apply.System also is included on the output beam 912 beam splitter 914 that is provided with, and is used to receive the photodetector 916 of the separating part of output beam 912, pulse counter circuit 918, controller 920 and be used to encourage the circuit 922 of little processing criterion tool 924.The photodetector 916 continuous monitoring lasers output that so is provided with.When laser switches or during saltus step, have of short duration interruption in its light output between pattern, its light output can be detected and be deposited and be pulse.When controller 920 was removed the electric excitation etalon of overall optical spectral limit, counter circuit 918 just induced the quantity of the generation and the count mode transition of moding, and it has comprised the reflection wavelength of the system with fixed wave length reflective-mode.Then, detector 916 provides feedback, so that the location of optimisation criteria tool 924, so that under the action required pattern, optimize power.Be adjusted to a temperature during the assembly technology or by the humidity control system on the TEC, the absolute position of pectination pattern just can be set, the pattern pectination of vertical pattern is in the center under a described temperature.
In the system that Fig. 9 a describes, some misoperations, noise effect or other fault may cause the track of moding meeting missing mode, cause the pattern offset error.Selectively, make the variation that variable total optical path length can produce initial modes.Just can remedy by setting up the local channel wavelength, as shown in Fig. 9 b, system uses this local channel wavelength, so that set up fixed datum.Except second beam splitter 926, " this locality " channel is carried out the tuning filter 928 and second photodetector 930, the system class of Fig. 9 b is similar to the system of Fig. 9 a.Diffraction grating, prism, etalon or similar device can be as replacing filter 928.Second beam splitter 926 is exported laser continuously and is taken a sample, and filters laser output by plate of low-pass optical interferometric filter 928, and its laser output with reference wavelength is transferred to second photodetector 930.The laser 902 that the signal indication of being deposited by second photodetector 930 is worked under the pattern corresponding to reference wavelength.Therefore, controller 920 is removed whole pattern by leaping voltage inspiring standard tool 924, and adds up the pattern quantity of the conversion in the removing by photodetector 916 and counting circuit 918.Therefore, laser 902 can be tuned as required any pattern, and quantity that can statistical model saltus step from reference mode.
From above-mentioned specification, these and other advantage of the present invention will be tangible for those of ordinary skills.Therefore, those of ordinary skills will be appreciated that, in not breaking away from wide invention idea of the present invention, can change and revise the foregoing description.Therefore, should be appreciated that to the invention is not restricted to specific embodiment described here, but the present invention wishes to comprise all changes and modification within the scope and spirit of the present invention that claims propose.
Claims (11)
1. method that is used to make little processing criterion tool comprises:
Crystalline substrates with first and second apparent surfaces is provided;
Provide wall on the first surface of this substrate, this wall has an outer surface;
Form one and extend through the through hole of this substrate up to second surface from first surface, this through hole has the substrate adjacent with the expose portion of this wall; And
Provide second interferometric filter providing on this outer surface of this wall on first interferometric filter and this expose portion, so that etalon is provided between interferometric filter at this wall.
2. according to the method that is used to make little processing criterion tool of claim 1, comprise the part wall of removing contiguous described through hole, between interferometric filter so that a slit is provided.
3. according to the method that is used to make little processing criterion tool of claim 2, comprise that contiguous described slit provides a conductive electrode, this electrode is configured to provide the repulsive force or the attraction of a change gap space.
4. according to any one the method that is used to make little processing criterion tool among the claim 1-3, wherein form through hole and comprise the anisotropic etching substrate.
5. little processing criterion tool comprises:
Crystalline substrates with first surface and second surface;
The wall that is provided with on the first surface of this substrate, this wall have an outer surface;
Extend through the through hole of this substrate until second surface from first surface, this through hole has a substrate that closes on the expose portion of this wall; And
Second interferometric filter that is provided with on first interferometric filter that is provided with on this outer surface of this wall and this expose portion at this wall is so that provide an etalon between interferometric filter.
6. exterior resonant cavity formula semiconductor laser comprises:
Gain medium is used to provide the light source of light radiation;
Be arranged to the external optical resonant cavity with this gain media optical communication, the size of this resonant cavity is enough short, so that allow single wavelength selector spare to select and keep single vertically emission zlasing mode; And
The single wavelength selector spare that is provided with in the optical resonator externally is so that select and keep single vertically emission zlasing mode.
7. according to the exterior resonant cavity semiconductor laser of claim 6, wherein wavelength selector spare comprises little processing criterion tool.
8. according to the exterior resonant cavity semiconductor laser of claim 7, wherein etalon comprises the variable spaces slit that can adjust to second size from first size, to be provided for launching laser under first vertical pattern or under second vertical pattern.
9. according to the exterior resonant cavity semiconductor laser of claim 7 or 8, wherein etalon comprises the electrode that contiguous slit is provided with, and is used to provide repulsive force or the attraction that changes gap space.
10. according to any one exterior resonant cavity semiconductor laser among the claim 6-9, wherein wavelength selector spare comprises monocrystalline silicon.
11. according to any one exterior resonant cavity semiconductor laser among the claim 6-9, wherein wavelength selector spare comprises:
Crystalline substrates with first and second apparent surfaces;
The wall that is provided with on the first surface of this substrate, this wall have an outer surface;
Extend through the through hole of this substrate until second surface from first surface, this through hole has the substrate adjacent with the expose portion of wall; And
Second interferometric filter that is provided with on first interferometric filter that is provided with on the outer surface of this wall and the expose portion at this wall is so that provide etalon between interferometric filter.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2020109856A (en) * | 2014-06-05 | 2020-07-16 | レニショウ パブリック リミテッド カンパニーＲｅｎｉｓｈａｗ Ｐｕｂｌｉｃ Ｌｉｍｉｔｅｄ Ｃｏｍｐａｎｙ | Laser device |
| CN113937616A (en) * | 2021-09-26 | 2022-01-14 | 中国科学院长春光学精密机械与物理研究所 | Semiconductor laser array, semiconductor laser single tube and preparation method thereof |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020109856A (en) * | 2014-06-05 | 2020-07-16 | レニショウ パブリック リミテッド カンパニーＲｅｎｉｓｈａｗ Ｐｕｂｌｉｃ Ｌｉｍｉｔｅｄ Ｃｏｍｐａｎｙ | Laser device |
| JP7199393B2 (en) | 2014-06-05 | 2023-01-05 | レニショウ パブリック リミテッド カンパニー | laser device |
| CN113937616A (en) * | 2021-09-26 | 2022-01-14 | 中国科学院长春光学精密机械与物理研究所 | Semiconductor laser array, semiconductor laser single tube and preparation method thereof |
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