GB2462805A - Semiconductor laser - Google Patents

Semiconductor laser Download PDF

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Publication number
GB2462805A
GB2462805A GB0814273A GB0814273A GB2462805A GB 2462805 A GB2462805 A GB 2462805A GB 0814273 A GB0814273 A GB 0814273A GB 0814273 A GB0814273 A GB 0814273A GB 2462805 A GB2462805 A GB 2462805A
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United Kingdom
Prior art keywords
laser
laser diode
light
optical
wave plate
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GB0814273A
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GB0814273D0 (en
Inventor
Bo Cai
Brian Joseph Kelly
John Francis O'carroll
Richard Philip Phelan
James O'gorman
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Eblana Photonics Ltd
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Eblana Photonics Ltd
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Priority to GB0814273A priority Critical patent/GB2462805A/en
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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4204—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
    • G02B6/4207—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms with optical elements reducing the sensitivity to optical feedback
    • G02B6/4208—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms with optical elements reducing the sensitivity to optical feedback using non-reciprocal elements or birefringent plates, i.e. quasi-isolators
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4204—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
    • G02B6/4207—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms with optical elements reducing the sensitivity to optical feedback
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
    • H01S3/0064—Anti-reflection devices, e.g. optical isolaters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/022—Mountings; Housings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/005—Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping
    • H01S5/0064—Anti-reflection components, e.g. optical isolators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/022—Mountings; Housings
    • H01S5/02208—Mountings; Housings characterised by the shape of the housings
    • H01S5/02212—Can-type, e.g. TO-CAN housings with emission along or parallel to symmetry axis
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/022—Mountings; Housings
    • H01S5/0225—Out-coupling of light
    • H01S5/02251—Out-coupling of light using optical fibres

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Semiconductor Lasers (AREA)

Abstract

The semiconductor laser 104 package includes a small quarter wave plate 102 arranged on the optical axis of the laser device and in close proximity to the output facet of the laser. The polarisation state of the light emitted by the laser is rotated by 45° any retro-reflected laser light is also rotated by a further 45°. The 90° change in the polarization state of the retro-reflected light reduces interferometric sub-cavity effects and also reduces light amplitude phase coupling which can cause emission coherence collapse. When the laser package incorporating the quarter wave plate is coupled to an optical fibre the optical isolation of the laser with respect to the back reflected light from the partially reflecting surface of the optical fibre is improved.

Description

A METHOD OF PACKAGING A LASER DIODE
FIELD
The present application relates to single wavelength laser diodes and in particular the simple low-cost packaging of said single wavelength laser diodes which eases the exploitation of the single-mode nature of the laser emission.
BACKGROUND
For many applications back-reflection of the light emitted by a laser diode into the laser active region has a significant, negative, impact on the performance of the laser. Under some conditions the back-reflection leads to spectral line narrowing and under other conditions it can lead to unstable operation making the laser emission unsuitable for use in many applications such as optical communications, sensing and metrology and Test and Measurement (Ref Tcatch and Chaprilvy) but also enabling others such as data storage.
For the purposes herein, light fed back into the laser diode can be grouped into two classes: reflection from distant reflectors where the distance between the laser emitting facet and the reflector (Lref) is greater than the coherence length of the laser emission (LCQh; c/Lw, where c is the speed of light and v is the laser line-width in Hz) and secondly when Lre < L0h. In the former case the laser instability has two components: an interferometric effect due to the coherent summation of the light emitted by the laser with the back-reflected light and secondly a nonlinear dynamic effect due to the large carrier density / index of refraction coupling that exists in inverted semiconductor media.
For light reflected from distant reflectors, Lref> 1Coh the interferometric effect is absent and the refractive index I carrier density coupling dominates. On the basis of these considerations, there have been proposed many methods to isolate the laser gain medium from reflected light. To date these methods have been complex and expensive to implement and have restricted use of single wavelength laser diodes in many applications.
Accordingly a low cost method of packaging single mode laser diodes that substantially reduced the impact of reflected light on the laser performance would be beneficial.
SUMMARY
In summary, the present application relates to the simple low-cost packaging of a semiconductor laser which reduces the impact of reflected light on the semiconductor laser operation so as to permit exploitation of the single mode nature of the laser emission in the presence of reflected light.
In one embodiment, a method of packaging a laser diode is provided comprising the step of placing a small quarter wave plate close to the emitting facet of the laser diode so that light emitted from the facet passes through the quarter wave plate.
The result of this is that the emission properties of the laser are substantially unaffected by light reflected from surfaces close to the emitting facet of the laser chip.
These needs and others will be met by the present application which is set out in detail in the description and\or claims which follow. The objects, features and advantages will become apparent from the following description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS -4-.
The application will now be described in greater detail having regard to the accompanying drawings in which: Figure 1 is a graph of the measured light current characteristics of a typical single mode laser diodes in the absence of optical feedback.
Figure 2 shows overlaid measured spectra illustrating the impact of feedback on the emission spectrum of a single mode DFB laser diode. The figure shows a substantially smooth spectrum obtainedin the absence of optical feedback and a broader spectrum with many features resulting from emitted light being retroflected into the laser. (The feedback evel was approximately -23dB).
Figure 3 is a graph of the measured light current characteristics of a DM single mode laser diode in the presence of optical feedback where a portion of the emitted light is retroflected into the laser, in this case from a cleaved fibre endface close to the laser chip resulting in a highly kinked characteristic. (Otherwise the operation conditions are as in Figure 1).
Figure 4 Schematic diagram of a typical TO can laser package modified so that a quarter wave plate is interposed close to the laser chip.
Figure 5 Schematic diagram illustrating the impact of a quarter wave plate on the polarization state of the propagating laser light after emission from the laser, before and after reflection by the reflector and after two transits through the quarter wave plate.
Figure 6 is a graph of the measured light current characteristics of a DM single mode laser diode in the presence of optical feedback where a small portion of the emitted light is retroflected into the laser from a cleaved fibre endface positioned close to the laser and a properly oriented quarter waveplate is interposed between the laser and the reflector.
For illustrative purposes the kinked light current characteristic of Figure 3 is also shown in the Figure (Otherwise the operation conditions are as in Figures 1 and 3).
DETAILED DESCRIPTION OF THE INVENTION
Known single-mode lasers suffer from the problem of their emission sensitivity to reflected!ight as described previously. Firstly, light reflected from nearby surfaces can create interferometric based instabilities due to the formation of interacting Fabry-Perot etalons by the reflecting surface (103) and the emitting facet of the laser (104). Secondly instabilities also arise from the fact that the laser diode optical cavity length, L0 = nL, is influenced by the presence or absence of reflected light (n is the average index of refraction of the laser diode waveguide and L is the physical length of the chip). While a wide range of phenomenology has been observed and are well known and discussed in the literature (for example R. W. Tkach and A. R. Chraplyvy) two distinct cases are to be made. Firstly where 1ref < L0h and secondly where Lref> L0h and the symbols have the same meanings as previously.
When Lref> L0h the instabilities which arise are due to interaction between the Fabry-Perot cavity formed by the laser chip and the Fabry-Perot formed by the the emitting facet of the laser 104 and the reflecting surface 103. In the case where Lref > L0 the instabilities which arise are primarily due to the second (highly nonlinear) effect where coupling between the index of refraction / optical carrier density / electromagnetic field phase shift lead to spectral instability and substantial accompanying laser intensity noise.
DFB laser diodes are single mode lasers well known and understood by those skilled in the art. DFB Jasing emission is strongly affected by both effects which necessitates the use of bulky complex and expensive Faraday isolators to prevent optical feedback. OM lasers diodes are also well known and understood by those skilled in the art but show a lesser sensitivity to light reflected from distant reflectors in their operation.
It is an object of the current application to eliminate or alleviate feedback noise that either results from interferometric originated mode competition (and selection) or instabilities that arise from the nonlinear interaction between the lasing mode supported by the semiconductor waveguide and cavity and the reflected tight field.
It is a further object of the current application to eliminate or alleviate feedback noise using a minimum of components ancillary to the laser package itself.
It is a yet a further object of the current application to isolate the laser diode chip from reflected light using a minimum of components ancillary to the laser package itself.
It is a final object of the current application to isolate the laser diode chip from reflected light using low cost a tow cost approach which does not require sensitive mechanical alignments and can be readily and cheaply implemented applied at all laser diode emission wavelengths.
Figure 1 shows the Light versus Current (Lvi) characteristic of a single-mode DM laser diode in the absence of retro-reflected light. The Lvi is highly linear and does not display kinks. In Figure 2 the smooth single peaked emission spectrum of a singlemode DFB laser in the absence of feedback(Figure 2, no feedback) shows lasing is occurring into a single narrow wavelength (mode of the laser cavity). Figure 2 also shows the optical spectrum where feedback Of Fdb -23dB of the DEB laser emission is retro-refiected into the laser. The spectrum in this case has multiple peaks and is significantly broadened. In contrast the Lvi characteristic of Figure 3 shows the impact of light retro-reflected from the flat endface of of a single mode fibre on the emission of a DM laser. The Lvi shows shows clear nonlinearity and kinks. It is well understood by those skilled in the art that lasers exhibiting such characteristics are unsuited for their main target applications due to their excessive emission intensity noise and non-constant emission spectra. (The multi-peaked spectrum of Figure 2 when feedback is present is actually due to the time averaging by the spectrum analyzer of the single laser mode wavelength which is fluctuating in time.) Conventionally the sensitivity of DFB lasers to retro-reftected light is addressed by interposing in the laser package an optical subassembly which permits throughput of light in one direction only. A typical optical isolator subassembly consists of two polarization elements (a polarizer and an analyzer having a 45°differential in the direction of their light transmission axes), and of a 45° Faraday rotator interposed between the polarization elements. A forward light passing the optical isolator undergoes the following: (1) when passing through the polarizer, the incident light is transformed into a linearly polarized light; (2) when passing through the Faraday rotator, the polarization plane of the now linearly polarized light is rotated through 45°; (3) this light passes through the analyzer without loss since its polarization plane is now in the same direction as the light transmission axis of the analyzer, which is tilted 450 from the polarizer in the direction of Faraday rotation. In contrast, backward reflected light undergoes a different process: (1) when passing through the analyzer, the backward light is transformed into a linearly polarized light with an initial 450 tilt in the transmission axis; (2) when passing through the Faraday rotator, the polarization plane of the backward light is now rotated a further 45°in the same direction as the initial tilt; (3) this light is consequently completely shut out by the polarizer because its polarization plane is now 900 away from the light transmission axis of the polarizer.
Polarization-dependent faraday isolators are primarily incorporated in semiconductor laser rriodules. Accordingly, miniaturization is an important aspect of the design. To realize this objective, the polarizing beam splitter is replaced by a lower cost infrared polarizing glass as a polarization element. Nonetheless Faraday isolators use exotic and expensive material for their proper operation: Bismuth substituted iron garnet films are used as Faraday rotators due to their low saturation magnetization and large rotation capacity while strong rare-earth magnets such as the Samarium-Cobalt type are often employed to apply the required large magnetic field to the Faraday rotator. The performance of opticalisolators is primarily evaluated by their insertion losses and isolations, both of which are determined by the absorption losses end-face reflectances, and the extinction ratios of the polarizing optical elements used.
This conventional approach suffers from a number of significant problems (I) cost, (ii) alignment sensitivity (iii) sensitivity of operation to coatings of optical subcomponents (iv) throughput and loss and finally (v) size. All of these factors have led to the Faraday isolator solution to be economically feasible only in high cost optical subassemblies used in low volume niche applications.
Even in diode lasers with bulk active regions (REF Chuang) a significant asymmetry in the lasing emission polarization arises due to the higher optical confinement factor and hence lower threshold current of the Transverse Electric (TE) waveguide mode in comparison to that of the Transverse Magnetic (TM) mode which consequently has a higher threshold current. In laser diodes with quantum well active regions the lifting of the degeneracy of the light hole and heavy hole valence bands due to the large differences in the quantum confined state energies of the light and heavy holes leads to large differences in their absorption and emission cross-sections. As a result the recombination between the electron in the conduction band and the light hole in the valence band (the origin of TE emission) dominates in quantum well lasers.
Strain in the active region, as is often used in compressively strained quantum well lasers to improve aspects of laser performance. This slightly reduces the heavy-hole light / hole splitting, and hence slightly reduces the laser materials' intrinsic polarization recombination asymmetry. Nonetheless the combination of these intrinsic polarization asymmetries in the optical constants of the materials with the greater TE confinement factor discussed previously leads to enhancement of the -12 -asymmetry in the emission polarization to an extent where even for compressively strained layer quantum well laser diodes emission is almost entirely in the TE polarization state and absorption and gain in the TM polarization are to all intents and purposes negligible.
S
Figure 4 shows a schematic diagram of an exemplary embodiment of this application employing a quarter wave plate while Figure 5 shows a schematic diagram illustrating the impact of a quarter wave plate on the polarization state of the propagating laser light after emission from the laser, before and after reflection by the reflector (103)and after two transits through the quarter wave plate (102). A laser diode chip (107) with emission predominantly in a single polarization state (here for convenience taken as the TE polarization state) is mounted in proximity to a quarter wave plate element (102) the optical axis of which is oriented such that the polarization plane of light emitted from the laser chip is rotated to a plane (106) which is oriented at 45° from the emission plane of polarization of (105) of the laser chip. This light upon retro-reflection by the reflector (103)and retransmission through the quarterwave plate is rotated by a further 45°. This retroreflected light upon being incident on the chip facet is now polarized (109)at 90° from the emitting polarization state (108) and corresponds to the TM polarized plane (110) of the laser waveguide into which it is coupled. -13-
This 9Q0 change in the polarization state has two main impacts. Firstly interferometric sub-cavity effects are reduced and secondly light amplitude phase coupling leading to emission coherence collapse is also reduced due to the polarization asymmetries of the quantum well materials.
Figure 6 shows the impact of imposing a quarter wave plate in the fashion described between the laser and the fiber cleaved end face of Figure 1 for the same operating conditions. It is obvious from the measured data that the impact of the light reflected from proximate reflectors on the laser emission is reduced to negligible levels. The LVI has returned to smooth linearity and for comparison purposes the kinked Lvl which is measured in the the absence of the quarter wave plate is shown for comparison.
It is useful to place this application in context with prior art. It is well known to those experienced in the field that strong optical isolation against accidentally reflected light is required for use of single mode lasers in many applications particularly where good coupling efficiency to optical fibres or instruments and systems are required.
Conventionally Faraday rotators are used as rotators of the polarization state due to their continuous rotation of the polarization state of the light field. Unfortunately 14 -such systems require use of a discrete polarizer to select a polarization state launched from the laser and a separate analyzer to also restrict the back-reflected light to a single polarization state. This leads to polarization selective losses (since light which is retro-reflected in the subassembly is lost if in the incorrect polarization); This can be overcome by use of expensive bi-refringent crystals as polarizers and analyzers.
The use of such a complicated expensive system is required since the light launched into a fibre has its polarization state randomized due to light scattering in the optical fibre. Consequently retro-reflected light can be in any polarization state when retroreflected and when it is incident on the isolator subassembly must therefore pass through an appropriately oriented polarizer before being incident on the rotator and analyzer.
In the current application a number of key elements contribute to its usefulness.
Firstly the high polarization anisotropy of the optical processes in strained layer quantum well lasers leads to a reduced impact on the stability of the lasing mode of retro-reflected light rotated to a polarization state perpendicular to that emitted by the laser. Secondly the compound cavity effects which arise from the coherent summation of emitted and retro-reflected light when Lref < 1coh are suppressed -15-because of the orthogonality in polarization of the interfering beams. Finally, since DM lasers are Fabry-Pérot laser diodes modified by surface etchings so as to lase in a single Fabry-Pérot mode of the cavity (i.e. they are a mode selected Fabry-Pérot laser diode) they are highly insensitive to those instabilities that arise when Iref> S Lc0 in which case the instabilities which arise are primarily due to nonlinear coupling between the index of refraction / optical carrier density and electromagnetic field phase shifts. Consequently for the DM laser any residual feedback to the laser chip in the TE mode arising from polarization state randomizing due to scattering in the fibre does not impact the DM laser performance in single-mode applications. It is for this reason that the quarter wave plate has such unobvious efficacy in use as an optical isolator.
Consequently the simple expedient of inserting a properly placed quarter wave plate in proximity to the laser chip facet and between the laser chip and any retro-reflector provides in practice sufficient immunity to optical feedback for application where currently more complex and expensive opticial isolator are required.
While in the description of the invention above reference has been only made to a TO-can package, those skilled in the art will recognize that the method can be applied to other package types including but not exclusively: silicon optical benches, planar lightwave circuits and butterf'y packages.
REFERENCES
R. W. Tkach and A. R. Chraplyvy, "Regimes of feedback effects in 1.5,um distributed feedback Iasers,"J. Lightw. TechnoL. vol. LT-4, no. 11, pp. 1655-1661, Nov. 1986.
Chuang, S.L.; O'Gorman, J.; Levi, A.F.J.;Quantum Electronics, IEEE Journal of, Volume 29, Issue 6, June 1993 Page(s):1631 -1639

Claims (21)

  1. CLAIMS1. A method of packaging a laser diode comprising the step of placing a small quarter wave plate close to the emitting facet of the laser diode so that light emitted from the facet passes through the quarter wave plate.
  2. 2. The method of Claim 1 where the laser diode lases in substantially a single mode.
  3. 3. The method of Claim 1 where the laser diode is a DFB laser.
  4. 4. The method of Claim 1 where the laser diode is a DM laser.
  5. 5. The method of Claim 1 where the packaged laser diode is used as a signal source for digital optical communications
  6. 6. The method of Claim S where the laser diode is used as a signal source for Gigabit Passive Optical Networks (GPO N).
  7. 7. The method of Claim 1 where the packaged laser diode is used as a signal source for Optical Datacomms
  8. 8. The method of Claim 7 where the iaser diode is used as a signal source for Internet Protocol (lP) based communications.
  9. 9. The method of Claim 1 where the packaged laser diode is used as a signal source for sensor and test and measurement applications.
  10. 1O.The method of Claim 9 where the packaged laser diode is used as a signal source for sensor optically pumped atomic and microwave clocks.
  11. 11.The method of Claim 9 where the packaged laser diode is used as a signal source for trace gas sensing
  12. 12.The method of Claim 1 where the packaged laser diode is used as a signal source for coherent optical communications.
  13. 13.The methods of claims 2-15 where the laser package is a TO can -19.-
  14. 14.The methods of claims 2-15 where the laser package is a silicon optical bench
  15. 15.The methods of claims 2-15 where the laser package is a planar lightwave circuit.
  16. 16. A laser assembly comprising: a laser diode for emitting light along an optical axis, a quarter wave plate element positioned along said optical axis.
  17. 17. A laser assembly according to claim 16, wherein the laser diode is adapted to provide a polarized light.
  18. 18. A laser assembly according to claim 17, wherein the quarter wave plate element is arranged such that the polarization plane of the light emitted from the laser diode is rotated to a plane which is oriented in the range of 40° to 500 (preferably about 45°) from the emission plane of polarization of the laser diode.
  19. 19. A laser assembly according to anyone of claims 16 to 18, wherein the laser diode is a single mode laser diode.
  20. 20. A laser assembly as claimed in claim 17, wherein that the quarter wave plate element the optical axis is oriented such that the polarization plane of the light emitted from the laser diode is rotated to a plane which is oriented about 450 from the emission plane of polarization of the laser diode.
  21. 21. A laser assembly as claimed in anyone of claims 16 or 20, further comprising an optical element positioned along the optical axis and configured to receive light from the laser, wherein in use the optical element at least partially reflects the light from the laser, with the polarization plane of this reflected light being rotated by 45°as it passes through the quarter wave plate.
GB0814273A 2008-08-04 2008-08-04 Semiconductor laser Withdrawn GB2462805A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108548656B (en) * 2018-03-29 2021-08-03 昂纳信息技术（深圳）有限公司 Test device and test system for TO-CAN laser

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4372644A (en) * 1979-11-10 1983-02-08 Licentia Patent-Verwaltungs-Gmbh Strip diode laser with reactance free fiber output
US20020118904A1 (en) * 2001-02-27 2002-08-29 Agere Systems Optical fiber systems for transmitting laser light with reduced back reflection interference
US6842467B1 (en) * 2000-03-08 2005-01-11 Finisar Corporation Fiber optic laser transmitter with reduced near end reflections
US20050089070A1 (en) * 2002-03-25 2005-04-28 Shoji Honda Semiconductor laser beam device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4372644A (en) * 1979-11-10 1983-02-08 Licentia Patent-Verwaltungs-Gmbh Strip diode laser with reactance free fiber output
US6842467B1 (en) * 2000-03-08 2005-01-11 Finisar Corporation Fiber optic laser transmitter with reduced near end reflections
US20020118904A1 (en) * 2001-02-27 2002-08-29 Agere Systems Optical fiber systems for transmitting laser light with reduced back reflection interference
US20050089070A1 (en) * 2002-03-25 2005-04-28 Shoji Honda Semiconductor laser beam device

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