WO2009115946A1 - Module de capteur optique - Google Patents

Module de capteur optique Download PDF

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Publication number
WO2009115946A1
WO2009115946A1 PCT/IB2009/051014 IB2009051014W WO2009115946A1 WO 2009115946 A1 WO2009115946 A1 WO 2009115946A1 IB 2009051014 W IB2009051014 W IB 2009051014W WO 2009115946 A1 WO2009115946 A1 WO 2009115946A1
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WO
WIPO (PCT)
Prior art keywords
optical
emitting laser
vertical cavity
surface emitting
cavity surface
Prior art date
Application number
PCT/IB2009/051014
Other languages
English (en)
Inventor
Armand Pruijmboom
Marcel F. C. Schemmann
Silvia M. Booij
Philipp H. Gerlach
Roger King
Steffan Intemann
Original Assignee
Philips Intellectual Property & Standards Gmbh
Koninklijke Philips Electronics N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Philips Intellectual Property & Standards Gmbh, Koninklijke Philips Electronics N.V. filed Critical Philips Intellectual Property & Standards Gmbh
Publication of WO2009115946A1 publication Critical patent/WO2009115946A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/36—Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light
    • G01P3/366—Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light by using diffraction of light
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/50—Systems of measurement based on relative movement of target
    • G01S17/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4814—Constructional features, e.g. arrangements of optical elements of transmitters alone
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/491—Details of non-pulse systems
    • G01S7/4912—Receivers
    • G01S7/4916—Receivers using self-mixing in the laser cavity
    • 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
    • H01S5/026—Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers
    • 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
    • H01S2301/00—Functional characteristics
    • H01S2301/18—Semiconductor lasers with special structural design for influencing the near- or far-field
    • 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
    • H01S5/0014—Measuring characteristics or properties thereof
    • H01S5/0028—Laser diodes used as detectors
    • 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
    • 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
    • H01S5/0233—Mounting configuration of laser chips
    • H01S5/0234—Up-side down mountings, e.g. Flip-chip, epi-side down mountings or junction down mountings
    • 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
    • H01S5/026—Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers
    • H01S5/0262—Photo-diodes, e.g. transceiver devices, bidirectional devices
    • 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
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/18—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities
    • H01S5/183—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
    • H01S5/18386—Details of the emission surface for influencing the near- or far-field, e.g. a grating on the surface
    • 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
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/18—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities
    • H01S5/183—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
    • H01S5/18386—Details of the emission surface for influencing the near- or far-field, e.g. a grating on the surface
    • H01S5/18388—Lenses

Definitions

  • the invention generally relates to the field of optoelectronic devices, and more specifically to optical sensor modules.
  • US 2006/0227844 Al describes an optical device with a vertical cavity surface emitting laser (VCSEL) and a lens which acts as a deflecting element so as to provide a light beam which is "off-axis" from the direction perpendicular to the emitter chip.
  • the lens is arranged on a post which is mounted to the chip. To deflect the beam, the optical axis of the lens is laterally displaced with respect to the optical axis of the VCSEL.
  • an optical sensor module comprises:
  • the optical sensor module is produced by means of a method comprising the steps of:
  • a vertical cavity surface emitting laser with functional layers disposed on a substrate, which laser emits light parallel to an optical axis of the laser which is perpendicular to the functional layers, and -furnishing the vertical cavity surface emitting laser with an optical deflecting element comprising a wedge or a grating, by attaching the optical deflecting element to or integrating it in the vertical cavity surface emitting laser so that the optical deflecting element deflects light emitted parallel to the optical axis of the vertical cavity surface emitting laser into a direction oblique to the optical axis.
  • a wedge deflects light due to a refraction surface extending obliquely to the optical axis of the vertical cavity surface emitting laser.
  • the grating acts as a deflecting element because the light is diffracted at the grating structure. Specifically, deflection by a grating is achieved due to diffraction into diffraction orders and selecting a partial beam diffracted into a diffraction order which is higher than the zero order.
  • the functional layers of the VCSEL are referred to as the layer stack which generates the laser light. Typically, the functional layers comprise Bragg-reflection layer stacks and at least one intermediate quantum well layer.
  • the sequence of the process steps is not necessarily of the order as defined above. Production of the VCSEL may be finished after furnishing the same with the deflecting element. If the deflecting element is integrated in the substrate of the
  • a deflecting optical element such as a grating or a wedge instead of a focusing lens allows the element to be placed very close to the laser cavity, even if a separate transparent optical deflecting element is used which is attached to the VCSEL.
  • VCSEL can be designed to be less than 100 micrometers, preferably less than 50 micrometers.
  • the oblique or beveled deflecting surface may have a distance of less than 100 microns at the location through which the center of the beam passes.
  • a preferred substrate material for the VCSEL is gallium arsenide, GaAs.
  • This material has a very high refractive index of more than 3.3 at a typical emission wavelength around 980 nm. Due to the high refractive index, a sufficient deflection is already achievable with a comparably shallow structuring of the substrate.
  • a deflecting structure which is integrated in the substrate may be overmolded with a transparent material.
  • the transparent material may preferably have a lower refractive index than the substrate. This facilitates encapsulation of the VCSEL because air gaps may be omitted, which may otherwise be necessary to provide a sufficient refractive index step for deflection.
  • the overmolding step helps to reduce the cost of packaging the module.
  • Suitable overmolding materials include transparent plastics such as polycarbonate (PC) or polymethyl methacrylate (PMMA)
  • the pitch of the grating may advantageously be less than the design wavelength of the VCSEL.
  • the design wavelength is understood to be the wavelength at which the VCSEL emits light.
  • the pitch may be less than 2/3 of the laser wavelength because a pitch chosen to be much smaller than the wavelength of the VCSEL results in additional advantages.
  • the grating can simultaneously function as an antireflection element.
  • the polarization of the light can be selected in dependence on the pitch.
  • a small pitch facilitates implementation of a combination of deflecting and converging properties for the grating.
  • a sensor element which is sensitive to the light emitted by the vertical cavity surface emitting laser may be additionally included. It is possible to integrate the sensor with the vertical cavity surface emitting laser. This can be accomplished by additionally applying or incorporating layers forming a photodiode or phototransistor to the VCSEL. These layers are preferably applied to the side of the stack of functional layers which is opposite to the side where the light is emitted. Alternatively or additionally, a separate sensor element may be employed.
  • an optical sensor module is the measurement of the velocity of a moving object.
  • the module may advantageously comprise circuitry for measuring the velocity of an object moving along a direction having a component along or opposite to the deflection direction of the beam deflected by the optical deflecting element.
  • the deflection direction is understood to be the component of the deflected beam perpendicular to the optical axis of the
  • the optical sensor module may be set up as a self-mixing sensor.
  • the light reflected or backscattered from an object is directed back into the cavity of the VCSEL. Due to interference with the light generated in the laser, the laser power is altered. If the object moves along a direction having a component along the light propagation path, the wavelength of the reflected or backscattered light is shifted. This shift results in a time- varying phase shift between the generated light and the backscattered or reflected light within the cavity.
  • the alteration of the laser power or laser intensity is a periodic modulation, in which the modulation frequency corresponds to the velocity of movement of the object.
  • the laser intensity may be measured with a photosensitive sensor element as mentioned above.
  • electrical parameters such as the electric power consumed by the VCSEL, the voltage drop across the VCSEL or the flowing current may be sensed.
  • the velocity of movement of an object moving along a direction perpendicular to the optical axis of the VCSEL may thus be gauged advantageously.
  • This allows, inter alia, a cost-effective production of optical input devices such as optical mice or pointing sticks or the like, wherein the VCSEL substrate can be mounted parallel to the bearing surface of the mouse facing the pad.
  • the VCSEL chip can be mounted directly onto a circuit board which is mounted parallel or substantially parallel to the surface whose velocity is to be sensed.
  • the VCSEL chip may be directly mounted onto a circuit board comprising further components of the circuitry such as logic circuitry of the interface and circuitry for determining parameters corresponding to the velocity components.
  • a deflection of the beam may serve to illuminate a region below a sensor so that the sensor and the VCSEL chip can be placed side by side on a substrate such as, in particular, a printed circuit board.
  • the deflection angle between the optical axis of the VCSEL and the deflected beam is preferably at least 15°, more preferably at least 20°, particularly preferably at least 25° and preferably less than 90° so as to facilitate sensing of a movement parallel to the VCSEL chip.
  • the deflection is accomplished by an asymmetrically shaped optical deflecting element.
  • An asymmetrically shaped optical deflecting element is herein understood to be an optical element which has different shapes or cross-sections along two mutually perpendicular directions extending laterally to the optical axis of the VCSEL.
  • a lens is rotationally symmetric so that the shape of its cross-section is independent of the choice of a section plane containing the optical axis.
  • the deflecting optical element may be asymmetrically shaped in such a way that the component of deflection lateral to the direction of the incident beam is within the same quadrant, independent of the point of incidence of the beam within the aperture or acceptance field of the deflecting element.
  • the component of deflection lateral to the incident beam can point to any direction vertical to the beam depending on the point of incidence.
  • a wedge or prism with a beveled deflecting refractive surface as well as a line grating is asymmetrically shaped in the sense of the afore-mentioned definition.
  • the optical deflecting element deflects a light beam from a direction parallel to the optical axis of the vertical cavity surface emitting laser to a predefined direction oblique to the optical axis of the vertical cavity surface emitting laser, preferably independently of or proximately from the lateral position of the beam within the aperture or acceptance field of the optical deflecting element.
  • the aperture or acceptance field is defined as the area vertical to the beam which is effective for the deflection.
  • the efficiency of deflecting the light by using a diffractive grating can be further improved if a stepped or blazed grating is used.
  • stepped or blazed gratings are more expensive to produce.
  • the deflecting element may have additional converging or focusing properties.
  • the surface of the wedge which extends obliquely to the optical axis of the VCSEL may specifically have a slightly curved refractive surface.
  • the wedge according to this embodiment of the invention may thus also be regarded as an optical element with a lens element having an optical axis which is tilted with respect to the optical axis of the VCSEL.
  • this optical element may also be defined as a wedge having a first, preferably plane surface facing the VCSEL and a second surface forming a lens having an optical axis which is tilted with respect to the normal of the first surface of the wedge and/or tilted with respect to the optical axis of the VCSEL.
  • the lines of the diffraction grating may also be curved and/or the pitch may vary so as to superimpose focusing and deflection.
  • the optical module may also comprise a focusing or converging optical element spaced apart from the deflecting element.
  • the focusing optical element is offset with respect to the optical axis of the vertical cavity surface emitting laser.
  • the beam emitted by the VCSEL is deflected by the optical deflecting element and subsequently focused by the focusing optical element.
  • the two functions of deflecting and converging the beam are thus split amongst two optical elements.
  • One optical element on the surface of the VCSEL deflects the beam to the desired direction, along which the focusing optical element is arranged.
  • a lens as a focusing element may be added to the housing of the optical sensor module. Since deflection has already been accomplished by the deflecting element disposed on or integrated in the VCSEL, the focusing optical element only has to converge the beam. Convergence, however, is substantially independent of the lateral position of the beam. Therefore, the deflection angle becomes less dependent on the positioning of the optical elements with respect to the beam or the optical axis of the VCSEL. Furthermore, a shorter focal length or, in line therewith, a higher numerical aperture of the focusing element can be chosen. If light backscattered from a surface at the focal point is detected, a focusing element with a high numerical aperture collects more backscattered light so that the signal strength increases substantially. In this regard, it is therefore preferred to use a lens having a focal length of less than 3 mm.
  • the focusing optical element may advantageously be arranged with its optical axis tilted with respect to the beam.
  • the optical axis of the focusing element may advantageously be parallel or substantially parallel to the optical axis of the VCSEL.
  • substantially parallel refers to an angle of preferably less than 10°, particularly preferably less than 5° between the optical axes of the VCSEL and the focusing optical element.
  • the deflecting element may have additional converging properties. This may be advantageous for reducing the divergence of the beam so that the beam diameter does not become larger than the aperture of the separate focusing element.
  • the grating or wedge may be integrated in or attached to the substrate of the VCSEL.
  • the VCSEL is preferably designed as a back-emitting laser, wherein the emitted light is transmitted through the substrate on which the functional layers are disposed. This embodiment is advantageous because furnishing of the VCSEL with the optical element does not influence the functional layers of the VCSEL.
  • the grating or wedge structure may generally be etched or otherwise introduced advantageously into the substrate of the VCSEL. Alternatively or additionally, methods other than etching may be employed to remove substrate material.
  • the deflecting element is integrated with the VCSEL is particularly advantageous in combination with the afore-mentioned back-emitting VCSEL. In this case, the deflecting structures may be introduced into the substrate without affecting the functional layers on the opposite side of the substrate. Accordingly, it is preferred for this embodiment of the invention to etch a grating or wedge into the substrate of the VCSEL on the side of the substrate opposite to the side on which the functional layers are disposed.
  • a lithography process may be employed to introduce the structures into the VCSEL.
  • the surface to be structured is coated with a resist which is subsequently exposed by light or electron beam illumination.
  • the resist is subsequently developed so that a pattern is formed therein, which is used as an etching mask.
  • the resist is removed so that a pattern of higher and lower regions is formed in the surface.
  • This method is particularly suitable for producing binary gratings.
  • a stepped grating may be produced by repeating the afore-mentioned steps with a suitable structuring of the masks.
  • gray-scale lithography may be employed to produce stepped or blazed gratings.
  • a wedge may be etched into the substrate.
  • Structuring by means of lithography can generally be accomplished with an accuracy of better than 3 micrometers, preferably of about 1 micrometer. This accuracy is generally sufficient to achieve the required tolerances of the deflection angle.
  • an optical sensor module with a deflecting optical element which can be produced with lower costs and comparable accuracy is therefore proposed.
  • the method is based on a sol-gel process. Basically, a sol-gel-layer is applied to the VCSEL. Then, while the sol-gel layer is still shapeable, a pattern is imprinted. A stamp may advantageously be used for imprinting the pattern. To avoid damage to the surface of the VCSEL, a flexible stamp is preferred.
  • a layer of a sol-gel material may be applied to the side of the substrate opposite to the side on which the functional layers of the laser are disposed. Then, a grating pattern or wedge pattern is formed in the layer by imprinting the pattern with the aid of a stamp. Subsequently, the layer is baked. This patterned and baked sol-gel material is then used as an etching mask for etching the substrate of the VCSEL.
  • the sol-gel-process may advantageously be carried out at wafer level prior to dicing individual VCSEL chips from the wafer.
  • the deflecting optical element is produced on the vertical cavity surface emitting laser by -applying a layer of a sol-gel material to the vertical cavity surface emitting laser, -forming a grating or wedge pattern in the layer by imprinting the pattern with the aid of a stamp, and
  • a further advantage is that blazed or stepped gratings as well as wedges and deflecting elements can be produced without further costs as compared to e.g. binary gratings once a stamp has been made for patterning with the complementary structure.
  • sol-gel layers having a high refractive index which allows overmolding and reduces reflection at the interface with the VCSEL-substrate, particularly if the substrate has a high refractive index, such as GaAs.
  • Ti ⁇ 2-layers can be produced from a sol-gel, e.g. by using tetraethyl orthotitanate or titanium tetra-isopropoxide as precursors.
  • Fig. 1 shows schematically a first embodiment of an optical sensor module according to the invention
  • Fig. 2 shows an embodiment of a VCSEL with an optical deflecting element usable in the sensor module shown in Fig. 1
  • Fig. 3 shows a variant of the embodiment shown in Fig. 2
  • Fig. 4 shows a comparison between the signal strengths for measuring the lateral velocity of a surface in front of the sensor module
  • Fig. 5 shows a schematic example of an overmolded VCSEL with a grating as deflecting element
  • Figs. 6 to 9 illustrate process steps of integrating a grating in the substrate of a VCSEL
  • Fig. 10 and Fig. 11 show variants of the optical sensor module of Fig. 1 with overmolded VCSELs.
  • Fig. 1 shows a first embodiment of an optical sensor module 1.
  • the optical sensor module comprises:
  • the optical sensor module 1 comprises an optical engine chip
  • the optical sensor module 1 shown in Fig. 1 further comprises circuitry, such as an ASIC 7 for processing the data generated by the optical engine chip 3.
  • Both the optical engine chip 3 and the ASIC 7 are mounted on a support 9.
  • the support may be a printed circuit board which also serves for wiring of the ASIC 7 with the optical engine chip 3.
  • a housing 11 defines a cavity 12 surrounding and encapsulating the optical engine chip 3 and the ASIC 7.
  • the housing 11 may be transparent or at least comprises an optically transparent window 14 for transmitting a light beam 13 emitted by VCSEL 5.
  • the VCSEL 5 is mounted with its optical axis perpendicular to the surface of the support. As can be seen from its optical path, the light beam 13 is deflected at the VCSEL with respect to the optical axis. The light beam 13 passes through the cavity 12 and the window 14 of the housing.
  • the optical sensor module 1 is further based on a concept in which the two functions of deflecting and focusing the beam are split amongst two elements.
  • a deflecting optical element is arranged on the surface of the VCSEL and deflects the beam in the desired direction.
  • a focusing optical element is spaced apart from the deflecting element at the VCSEL, which focusing optical element is offset with respect to the optical axis of the vertical cavity surface emitting laser so that the beam 13 emitted by the VCSEL and deflected by the optical deflecting element is focused by the focusing optical element.
  • This converging or focusing optical element is obtained by a transparent window 14 with a lens 15.
  • the lens focuses the beam 13 onto a surface 19. Due to the deflection at the VCSEL, the beam 13 impinges upon the surface 19 at an inclined angle of incidence. Since this optical element only has to converge the beam, it can be used on-axis. In other words, the lens is positioned in such a way that the lateral position of the optical axis of lens 15 is at or near the central ray of the beam 13. In this way, the deflection angle of the beam 13 becomes less dependent on the adjustment of the optics. Furthermore, the lens can be positioned close to the surface 19 so that a lens having a high numerical aperture can be used. This is advantageous for achieving a high signal strength and/or a high signal-to-noise ratio of the detected signal.
  • the deflection of the laser beam 13 at the VCSEL 5 allows illumination of the surface 19 at an inclined angle with the support 9 which is arranged parallel to surface 19. This is advantageous if it is desirable to arrange the support or the optical engine close to the surface 19.
  • a preferred application of the module as schematically shown in Fig. 1 is the detection of movement of the surface 19.
  • the optical sensor module 1 may be part of an optical mouse.
  • the optical sensor module may be set up to detect the velocity component of a movement of the sensor module along the surface 19 and parallel or anti-parallel to the direction of deflection.
  • the optical sensor module 1 may be set up as a self-mixing sensor.
  • This sensor is based on the principle that light which is backscattered from surface 19 follows the optical path of the incident light in the opposite direction and is introduced into the laser cavity of the VCSEL 5. The backscattered light interferes with the generated light and thereby alters the overall light intensity.
  • the frequency of the backscattered light will be Doppler-shifted, which results in a time-varying phase shift between generated and backscattered light. Accordingly, the overall light intensity becomes time-dependent as well.
  • a periodically varying power fluctuation is generated, with the frequency of this periodic fluctuation corresponding to the velocity.
  • Fig. 2 is an enlarged view of an embodiment of a VCSEL 5 which may be used in the optical sensor module 1 shown in Fig. 1.
  • the VCSEL 5 comprises a substrate 50 having two facing sides 51, 52.
  • Substrate 50 is preferably a GaAs substrate.
  • a stack 55 of functional layers defining the laser cavity of the VCSEL 5 is disposed on side 51.
  • the VCSEL is designed as a back-emitting laser, wherein the laser light is emitted towards and transmitted vertically through the substrate 50 so that the laser light exits on side 52. Accordingly, the optical axis of the VCSEL 5 is perpendicular to the surfaces of sides 51, 52.
  • a front-emitting VCSEL having an optical axis perpendicular to the substrate surface may also be used.
  • a wedge 20 of transparent material as an optical deflecting element is mounted on side 52 of the VCSEL 5.
  • the wedge 20 has a first surface 21 facing side 52 of the substrate 50 and a second surface 22 extending obliquely to the first surface 21 and the optical axis of the VCSEL 5.
  • the wedge 20 has an overall height of preferably less than 50 micrometers. According to this embodiment, the point of the surface 21 through which the center of the beam passes is thus spaced apart from side 52 of the VCSEL 5 by less than 50 micrometers. Due to the difference of the refractive indices of the wedge material and the cavity, the laser beam 13 is deflected upon passing through the oblique surface 22.
  • the wedge 20 deflects light from a direction parallel to the optical axis of the VCSEL 5 to a predefined direction oblique to the optical axis of the VCSEL 5 and independent of the lateral position of the beam 13 within the aperture of the optical deflecting element.
  • Fig. 3 is a variant of the embodiment shown in Fig. 2.
  • a prism or wedge 20 is used as a deflecting element.
  • the wedge 20 is shaped similarly as in the example shown in Fig. 2.
  • the second surface 22, which extends obliquely to the optical axis of the VCSEL 5 is additionally convexly curved. Due to refraction of the beam at this surface, the beam is thus bent and converged.
  • the beam 13 is still slightly divergent after passing through surface 22 of wedge 20.
  • the beam 13 does not necessarily need to be focused to a convergent beam because focusing is accomplished by lens 15 of the module shown in Fig. 1.
  • Fig. 4 shows a comparison of graphs of the optical efficiencies for determining the lateral velocity of a surface 19 versus the distance of the VCSEL to the surface 19.
  • Curve 25 is the optical efficiency of a design with a VCSEL having a single lens as a deflecting and focusing element on the VCSEL.
  • Curve 26 is the optical efficiency of a setup as shown in Fig. 1.
  • Curve 27 is a simulation of the worst offender in miss-alignment of this design. The similarity of the curves 26 and 27 demonstrates the robustness with respect to misalignment. As can be seen from a comparison of curves 25 and 26, an increase in signal strength by about a factor of 10 can be achieved as compared to a setup with a single lens on the VCSEL.
  • Fig. 5 shows a further embodiment of a VCSEL 5 with a deflecting element.
  • a back-emitting VCSEL 5 is used.
  • a grating 57 is etched into side 52 of the substrate 50 opposite to side 51 on which the stack 55 of functional layers is deposited. Accordingly, the grating as a deflecting element is integrated with the VCSEL 5 in this embodiment.
  • the substrate has a very high refractive index of more than 3.3 in the near infrared region.
  • the grating 57 and/or the entire VCSEL 5 may therefore be overmolded with a transparent plastic material 60 because suitable plastic materials typically have much lower refractive indices.
  • a polycarbonate overmold typically has a refractive index of between 1.58 and 1.6. Accordingly, the refractive index difference at the interface between substrate 50 and overmolded plastics material 60 is still high enough to provide sufficient diffraction efficiency without the need for deep etching grooves. Furthermore, both deflection and convergence can be realized by the grating 57 integrated in the VCSEL 5, by etching the grating 57 into the substrate material. When the grating is chosen to have a pitch which is much smaller than the wavelength of the light, additional advantages are obtained in that the layer can simultaneously function as an anti-reflection coating, in that polarization of the light can be selected in dependence on the structure, and in that deflection and/or converging of the beam can be combined.
  • grating 57 which may be different in the two lateral directions.
  • the grating 57 shown in Fig. 5 has a varying pitch.
  • the varying pitch may be combined with curved grating lines so as to superimpose converging properties on the deflection.
  • the grating shown in Fig. 5 is a binary grating.
  • binary gratings deflect light into several orders of diffraction with similar intensity.
  • stepped or blazed gratings so that most intensity is diffracted in a single order, which is desirable to reduce losses.
  • gray-scale lithography may be employed to etch these structures.
  • -a grating or wedge pattern is formed in the layer by imprinting the pattern with the aid of a stamp
  • the layer is subsequently baked, and - the substrate is etched by using the patterned and baked sol-gel material as an etching mask.
  • the method is preferably carried out at wafer level before separating chips from the wafer.
  • a layer 61 of sol-gel material is applied to side 52 of a wafer substrate 49, preferably a GaAs wafer.
  • the sol-gel-material may be applied by means of e.g. spin-coating, spray-coating, dip-coating or screen-printing.
  • Fig. 6 further shows a flexible stamp 63, e.g. of elastomeric material, having a grating pattern relief 64. Specifically, the grating pattern is blazed and has grooves 65 with sloped surfaces 66. The stamp 63 is used to imprint the pattern into the layer 61.
  • the imprinting step is shown in Fig. 7.
  • the stamp 63 is pressed onto side 52 of wafer substrate 49 so that the sol-gel material of layer 61 which is still shapeable fills the grooves 65.
  • the layer is thermally consolidated or baked and the stamp 63 is removed. If required, further baking may be applied after removing stamp 63.
  • the 64 of the stamp 63 has been transferred to the sol-gel layer which is now structured with a complementary grating pattern 67 with grooves 68 and sloped groove walls 69.
  • the wafer 49 is then etched on side 52 until the sol-gel layer is removed due to etching so that the complementary grating pattern is transferred to the wafer surface.
  • a blazed grating 70 with grooves having groove walls 71 sloped with respect to the original surface normal of side 52 is formed in the wafer 70.
  • the functional layers of the VCSELs may be deposited on opposite side 51 and individual VCSEL chips may be diced from the wafer 49.
  • the grating 70 may be introduced after producing the VCSEL dies on side 51. Again, overmolding with a transparent plastics material may be applied as shown in Fig. 5 so as to package and encapsulate the VCSEL. The resulting VC SEL is shown in Fig. 9.
  • the etching step may be omitted because the sol-gel layer shown in Fig. 8 forms a grating as well.
  • the grating pattern 67 may also be overmolded if a sol-gel layer having a high refractive index is applied.
  • a sol-gel based on titanium tetra-isopropoxide as a precursor may be employed to produce a titanium oxide containing sol-gel layer.
  • an additional focusing lens similarly as in the embodiment shown in Fig. 1 may be omitted.
  • a module with a focusing lens 15 similarly to the embodiment shown in Fig. 1 may be used, wherein the lens is formed in the overmolding step.
  • the cavity 12 may be omitted in both cases.
  • FIGs. 10 and 11 An embodiment of an optical sensor module 1 with overmolded VCSEL 5 having a grating 70 as an integrated optical deflecting element and a lens 15 as a focusing element formed in the overmolding step is shown in Fig. 10.
  • the embodiment of the optical sensor module 1 shown in Fig. 11 has an overmolded VCSEL 5 as well.
  • the surface area of the overmold 60, where the laser beam 13 exits, is substantially plane. Focusing and deflection is accomplished by the grating 70 in the VCSEL 5.
  • Embodiments without a cavity 12, such as the examples shown in Figs 10 and 11, are also advantageous in that the deflection angle at the grating is independent of the refractive indices of the materials, but rather depends on the pitch. Due to refraction, the deflection angle then further increases at the air interface of the overmold.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Power Engineering (AREA)
  • Optics & Photonics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Semiconductor Lasers (AREA)
  • Optical Couplings Of Light Guides (AREA)

Abstract

La présente invention concerne un module de capteur optique (1), comprenant un laser à cavité verticale et à émission par la surface (5). Un élément optique de déviation est fixé ou intégré au laser à cavité verticale et à émission par la surface (5) de façon à dévier le faisceau laser (13) selon une direction oblique par rapport à l'axe optique du laser (5).
PCT/IB2009/051014 2008-03-18 2009-03-11 Module de capteur optique WO2009115946A1 (fr)

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EP08102699.9 2008-03-18

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3062546A1 (fr) * 2017-02-01 2018-08-03 Institut Vedecom Structure de diffraction integree dans une carte de circuit imprime et procede de fabrication de celle-ci
US20190067898A1 (en) * 2017-08-29 2019-02-28 Osram Opto Semiconductors Gmbh Laser component, use of a laser component, device having laser component and method of producing laser components
JP2019522778A (ja) * 2016-05-19 2019-08-15 コーニンクレッカ フィリップス エヌ ヴェＫｏｎｉｎｋｌｉｊｋｅ Ｐｈｉｌｉｐｓ Ｎ．Ｖ． 粒子センサー、粒子検出方法及びコンピュータ・プログラム
WO2020214097A1 (fr) * 2019-04-17 2020-10-22 Ams Sensors Asia Pte. Ltd. Dispositif laser à émission par la surface à cavité verticale

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005106635A1 (fr) * 2004-04-29 2005-11-10 Koninklijke Philips Electronics N.V. Dispositif d'entree optique et procede de mesure du deplacement relatif d'un objet et dispositif d'entree optique
US20060056476A1 (en) * 2004-09-14 2006-03-16 Fuji Photo Film Co., Ltd. Laser diode with corner reflector having emission window
US20060227844A1 (en) * 2005-04-11 2006-10-12 Guenter James K On-chip lenses for diverting vertical cavity surface emitting laser beams
GB2434914A (en) * 2006-02-03 2007-08-08 Univ College Cork Nat Univ Ie Vertical cavity surface emitting laser device
US7286581B2 (en) * 2004-08-20 2007-10-23 Avago Technologies Fiber Ip (Singapore) Pte Ltd Self-monitoring light emitting apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005106635A1 (fr) * 2004-04-29 2005-11-10 Koninklijke Philips Electronics N.V. Dispositif d'entree optique et procede de mesure du deplacement relatif d'un objet et dispositif d'entree optique
US7286581B2 (en) * 2004-08-20 2007-10-23 Avago Technologies Fiber Ip (Singapore) Pte Ltd Self-monitoring light emitting apparatus
US20060056476A1 (en) * 2004-09-14 2006-03-16 Fuji Photo Film Co., Ltd. Laser diode with corner reflector having emission window
US20060227844A1 (en) * 2005-04-11 2006-10-12 Guenter James K On-chip lenses for diverting vertical cavity surface emitting laser beams
GB2434914A (en) * 2006-02-03 2007-08-08 Univ College Cork Nat Univ Ie Vertical cavity surface emitting laser device

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019522778A (ja) * 2016-05-19 2019-08-15 コーニンクレッカ フィリップス エヌ ヴェＫｏｎｉｎｋｌｉｊｋｅ Ｐｈｉｌｉｐｓ Ｎ．Ｖ． 粒子センサー、粒子検出方法及びコンピュータ・プログラム
FR3062546A1 (fr) * 2017-02-01 2018-08-03 Institut Vedecom Structure de diffraction integree dans une carte de circuit imprime et procede de fabrication de celle-ci
WO2018142055A1 (fr) * 2017-02-01 2018-08-09 Institut Vedecom Carte électronique à circuit imprimé comprenant une structure de diffraction integrée et procédé de fabrication de celle-ci
US10912191B2 (en) 2017-02-01 2021-02-02 Institut Vedecom Electronic card with printed circuit comprising an integrated diffraction structure and method for the production thereof
US20190067898A1 (en) * 2017-08-29 2019-02-28 Osram Opto Semiconductors Gmbh Laser component, use of a laser component, device having laser component and method of producing laser components
DE102017119778A1 (de) * 2017-08-29 2019-02-28 Osram Opto Semiconductors Gmbh Laserbauelement, Verwendung eines Laserbauelements, Vorrichtung mit Laserbauelement und Verfahren zur Herstellung von Laserbauelementen
US10673202B2 (en) 2017-08-29 2020-06-02 Osram Oled Gmbh Laser component, use of a laser component, device having laser component and method of producing laser components
WO2020214097A1 (fr) * 2019-04-17 2020-10-22 Ams Sensors Asia Pte. Ltd. Dispositif laser à émission par la surface à cavité verticale

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