VCSEL device of SMI sensor for recording 3D images

Abstract

The invention relates to a vertical cavity surface emitting laser (VCSEL) device (100) of a self-mixing interferometric sensor (300) for recording three-dimensional images, the VCSEL device (100) comprising a VCSEL array, a plurality of detectors (140), a first electric laser contact (105) and at least one second electric laser contact (127), wherein the VCSEL array comprises a plurality of laser diodes (122), wherein each laser diode (122) comprises an optical resonator, wherein the optical resonator comprises a first distributed Bragg reflector (115), a second distributed Bragg reflector (135) and an active layer (120) for emitting light, wherein the active layer (120) is arranged between the first distributed Bragg reflector (115) and the second distributed Bragg reflector (135). A distributed Bragg reflector (135) is provided, wherein a first electric laser contact (105) and the at least one second electric laser contact (127) are arranged to provide an electric drive current to electrically pump an optical resonator of a laser diode (122), wherein the first electric laser contact (105) is a common contact for all laser diodes (122) of a VCSEL array, wherein the at least one second electric laser contact (127) is arranged to be able to make electrical contact with at least a subset of the plurality of laser diodes (122) of the VCSEL array, wherein each detector (140) is arranged to generate an electric self-mixing interferometry signal associated with at least one laser diode (122) upon receiving laser light (10). The present invention also relates to a self-mixing interferometry sensor (300) for recording three-dimensional (3D) images, a VCSEL device, and a method for manufacturing such a VCSEL device.

Description

Technical Field

[0001] The present invention relates to a vertical cavity surface emitting laser (VCSEL) device for a self-mixing interference (SMI) sensor for recording three-dimensional (3D) images, an SMI sensor, and a mobile communication device including the VCSEL device or the SMI sensor. The present invention also relates to a corresponding method for manufacturing such a VCSEL device. Background Art

[0002] Current state-of-the-art optical 3D sensors require high-power light sources and corresponding detectors. Optical alignment complexity, power consumption, and eye safety are key issues.

[0003] WO2017 / 016888A1 discloses a laser sensor module for particle density detection. The laser sensor module may include an array of multiple laser diodes.

[0004] US 2011 / 0064110 A1 discloses a vertical cavity surface emitting laser device with a monolithically integrated photodiode.

[0005] US 2003 / 0021327 A1 discloses a vertical cavity surface emitting laser device comprising a photodetector deposited directly onto the top surface of the laser structure. Summary of the Invention

[0006] The object of the present invention is to provide an improved VCSEL device for an SMI sensor for recording three-dimensional images.

[0007] According to a first aspect, a vertical cavity surface emitting laser (VCSEL) device for a self-mixing interferometer sensor for recording three-dimensional images is provided. The VCSEL device includes a VCSEL array, a plurality of detectors (e.g., optical detectors, such as photodiodes or phototransistors), a first electric laser contact, and at least one second electric laser contact. The VCSEL array includes a plurality of laser diodes (VCSELs). The plurality of laser diodes can be arranged on a common substrate. The common substrate can be, for example, a growth substrate used to grow semiconductor layers included in the VCSEL array or a substrate bonded to the VCSEL array in a subsequent processing step. Each laser diode includes an optical resonator. The optical resonator includes a first distributed Bragg reflector, a second distributed Bragg reflector, and an active layer for emitting light. The active layer is arranged between the first distributed Bragg reflector and the second distributed Bragg reflector. The first electric laser contact and the at least one second electric laser contact are arranged to provide an electrical drive current to electrically pump the optical resonator of the laser diode. The first electric laser contact is a common contact for all laser diodes in the VCSEL array. The at least one second electrical laser contact is arranged to be able to electrically contact at least a subset of the plurality of laser diodes of the VCSEL array. Each detector can be arranged to receive laser light from at least one laser diode (optical detector) of the VCSEL array. Each detector is arranged to generate an electrical self-mixing interferometry signal associated with the at least one laser diode (optical detector, electrical detector, etc.) upon receiving the laser light. Each detector can be associated with one, two, three, four, or more laser diodes. The subset of the plurality of laser diodes of the VCSEL array can include, for example, columns or rows of the VCSEL array. If a laser diode (VCSEL) emits laser light and a portion of the emitted laser light is reflected back into the optical resonator of the corresponding laser diode, a self-mixing interference signal is generated. The reflected laser light interferes with a standing wave pattern within the optical resonator or laser cavity, thereby generating a self-mixing interference signal. The self-mixing interference signal can be detected by means of a detector (for example, a change in laser light intensity within the optical resonator can be detected, for example, by means of a photodiode).

[0008] The plurality of laser diodes may comprise more than 100 laser diodes. The plurality of laser diodes may in particular comprise at least 1000, preferably at least 5000 and most preferably at least 10000 laser diodes. The VCSEL array may even comprise more than 100000 laser diodes (e.g., VGA resolution of 640×480 pixels, etc.).

[0009] The VCSEL device may include two, three, four or more second electric laser contacts. In this embodiment, each second electric laser contact is arranged to electrically drive a corresponding subset of the laser diodes of the VCSEL array. The second electric laser contact may, for example, be an anode laser contact. The first anode contact may be combined with the first electric laser contact (common cathode contact) to provide an electrical drive current to the first column or first row of the VCSEL array. Thus, the anode contact may enable the corresponding subset to be switched on or off independently of the other subsets. The detectors may, for example, be arranged in a complementary arrangement relative to the arrangement of the subsets of the VCSEL array. For example, if the laser diodes of the VCSEL array are arranged in columns, the detectors may be arranged in rows. Even if an entire column of laser diodes emits laser light and generates a corresponding self-mixing interference signal in each optical resonator, the matrix arrangement enables a single self-mixing interference measurement result corresponding to one laser diode signal to be read by means of one detector. The matrix arrangement simplifies the contacting of the detectors, but requires a corresponding switching scheme. An alternative approach is to provide a dedicated detector for each laser diode, so that it is clear which laser diode generates the corresponding self-mixing interferometry signal.

[0010] According to an alternative embodiment, the VCSEL arrangement can include a second electrical laser contact, wherein the first and second electrical laser contacts are arranged to provide a common electrical drive current to all laser diodes in the VCSEL array. In this embodiment, each detector is associated with a dedicated laser diode, enabling identification of the corresponding self-mixing interferometry signal. This embodiment can enable very fast measurements of 3-D settings or scenes.

[0011] The detector can be integrated into the optical resonator. The detector can be integrated, for example, into the first distributed Bragg reflector or the second distributed Bragg reflector. The detector can be integrated, for example, into an unstructured DBR, so that, as described above, a common detector can be arranged to receive self-mixing interference signals from two, three, four, or more VCSELs. The detector can be integrated, for example, into the first (lower) DBR to provide a common detector for adjacent VCSELs.

[0012] Each optical resonator can include a dedicated detector. In this case, the assignment between the laser diode and the corresponding dedicated detector is clear, thus simplifying the identification of the self-mixing interference signal.

[0013] Each detector can include a first detector electrode. The first detector electrode and at least one additional electrode are arranged to read the electrical self-mixing interferometry signal. The additional electrode can be included in the first electric laser contact or the second electric laser contact. In this case, the corresponding laser diode and detector share a common electrode or contact. Alternatively, the additional electrode can be a separate second detector electrode independent of the first and second electric laser contacts.

[0014] The at least one additional electrode can be at least one second electric laser contact. The detector is integrated in the second distributed Bragg reflector. The VCSEL array is arranged so that during operation of the VCSEL device, laser light is emitted via the first distributed Bragg reflector. In this case, the laser diode (VCSEL) is a so-called bottom emitter, which emits laser light through the substrate if the substrate is not removed in the direction opposite to the side of the substrate adjacent to the optical resonator. In this case, the emission wavelength is such that the (GaAs) substrate is transparent (for GaAs, the emission wavelength is greater than 900 nm), for example 940 nm. Alternatively, the substrate can be at least partially removed. The first detector electrode of the detector can be contacted by wire bonding. The self-mixing interferometry measurement signal can be read from each individual detector (e.g. a photodiode or a phototransistor).

[0015] The VCSEL arrangement can alternatively be arranged as a flip-chip arrangement. The topmost first detector electrode can (e.g. completely) cover the mesa of the corresponding laser diode (VCSEL). The first detector electrode is a (e.g. complete) metal contact that can be flipped on the chip. The second electrical laser contacts of a subset (e.g., the entire laser array, column or row) can be electrically contacted, e.g., by means of wire bonds, so that each detector (pixel) can be read via a simple electrical connection. All laser diodes (VCSELs) can be operated simultaneously or group by group.

[0016] According to an alternative embodiment, the VCSEL array can be mounted on a detector chip. The detector chip includes detectors. The detector chip can be, for example, a silicon-based detector chip that includes an array of photodetectors, wherein each photodetector is aligned with a corresponding laser diode (VCSEL) included in the VCSEL array. The detector chip can alternatively include, for example, rows or columns of photodetectors, which can be arranged in a matrix arrangement relative to the subgroups of laser diodes as discussed above.

[0017] The VCSEL array includes at least one optical device configured to redirect laser light. The optical device may include, for example, a lens, a lens array, a diffuser, or the like, to diffuse the laser light emitted by the VCSEL array within a defined field of view. The at least one optical device may be an optical structure etched into a substrate (e.g., a gallium arsenide growth substrate) included in the VCSEL array.

[0018] According to another aspect, a self-mixing interferometer sensor for recording a three-dimensional image is provided, the self-mixing interferometer sensor comprising a VCSEL device according to any of the embodiments discussed above. The three-dimensional self-mixing interferometer sensor further comprises a drive circuit and an analysis and evaluation device. The drive circuit is arranged to be able to electrically drive the laser diode by means of the first electric laser contact body and the at least one second electric laser contact body. The analysis and evaluation device is arranged to be able to analyze and evaluate the electrical self-mixing interferometer measurement signal. For example, the analysis and evaluation device can be arranged to be able to determine the distance, speed and / or acceleration of an object based on the self-mixing interferometer signal in each optical resonator or laser cavity of the laser device included in the VCSEL array. The analysis and evaluation device can also be arranged to be able to reconstruct a three-dimensional image of the field of view and the objects in the field of view based on multiple distances, speeds and / or accelerations.

[0019] According to another aspect, a mobile communication device may include a VCSEL device according to any of the embodiments described above or a three-dimensional self-mixing interferometer sensor as described above. As described above, the mobile communication device is arranged to be able to present a three-dimensional image of a scene to a user of the mobile communication device based on a self-mixing interferometer measurement signal of the scene. The analysis and evaluation of the self-mixing interferometer measurement signal can be performed by a laser sensor and / or the mobile communication device. The VCSEL device or the three-dimensional self-mixing interferometer sensor can also be included in a 3-D camera.

[0020] According to another aspect, a method for manufacturing a vertical cavity surface emitting laser (VCSEL) device for a self-mixing interferometer sensor for recording three-dimensional images is provided. The method comprises the following steps:

[0021] Set the base,

[0022] A VCSEL array including a plurality of laser diodes is provided on a substrate, wherein each laser diode includes an optical resonator, wherein the optical resonator includes a first distributed Bragg reflector, a second distributed Bragg reflector, and an active layer for emitting light, wherein the active layer is arranged between the first distributed Bragg reflector and the second distributed Bragg reflector.

[0023] providing a first electric laser contact, wherein the first electric laser contact is a common contact for all laser diodes of the VCSEL array,

[0024] providing at least one second electric laser contact, wherein the first electric laser contact and the at least one second electric laser contact are arranged to be capable of providing an electric drive current for electrically pumping an optical resonator of the laser diode, wherein the at least one second electric laser contact is arranged to be capable of making electrical contact with at least a subset of the plurality of laser diodes of the VCSEL array,

[0025] Detectors are provided, wherein each detector is arranged to generate an electrical self-mixing interferometry signal associated with the at least one laser diode upon receiving laser light.

[0026] These steps do not need to be performed in the order given above. The different layers can be deposited by epitaxial methods such as MOCVD, MBE, etc. The substrate can be removed in a subsequent processing step.

[0027] It shall be understood that the VCSEL array and the method of manufacturing a VCSEL device according to any embodiment described above have similar and / or identical embodiments, in particular as defined in the dependent claims.

[0028] It shall be understood that a preferred embodiment of the present invention can also be any combination of the dependent claims with the corresponding independent claim.

[0029] Further advantageous embodiments are defined below. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0031] The present invention will now be described by way of example based on embodiments with reference to the accompanying drawings.

[0032] In the attached figure:

[0033] Figure 1 A schematic diagram of a cross section of a first VCSEL device with an integrated detector is shown.

[0034] Figure 2 A schematic diagram of the electrical contact scheme of a first VCSEL device is shown.

[0035] Figure 3 A schematic diagram showing a top view of a first VCSEL device is shown.

[0036] Figure 4 A simplified schematic diagram of a second VCSEL device with a detector chip is shown.

[0037] Figure 5 A schematic diagram of a third VCSEL device with a detector chip is shown.

[0038] Figure 6 A schematic diagram of the principle of a self-mixing interferometric sensor is shown.

[0039] Figure 7 An embodiment of a mobile communication device including a self-mixing interferometric sensor is shown.

[0040] Figure 8 A schematic diagram showing the process flow of a method for manufacturing a VCSEL device.

[0041] In the drawings, like reference numerals refer to like objects throughout. Objects in the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0042] Various embodiments of the present invention will now be described with the aid of the accompanying drawings.

[0043] Self-mixing interferometry is used to detect the motion of an object and the distance to the object. Background information on self-mixing interferometry is described in "Laser diode self-mixing technique for sensing applications" by Giuliani, G.; Norgia, M; Donati, S. & Bosch, T., in "Laser diode self-mixing technique for sensing applications", Journal of Optics A: Pure and Applied Optics, 2002, 4, S.283-S.294, incorporated herein by reference. Detection of the motion of a fingertip relative to a sensor in an optical input device is described in detail in International Patent Application No. WO02 / 37410, incorporated herein by reference. The principle of self-mixing interferometry is discussed based on the example presented in International Patent Application No. WO02 / 37410. A diode laser having a laser cavity or an optical resonator is provided for emitting a laser or measuring light beam. The device is provided with a transparent window at its upper side, across which an object, such as a human finger, moves. A lens is arranged between the diode laser and the window. This lens focuses the laser beam at or near the upper side of the transparent window. If an object is present at this location, it scatters the measurement beam. A portion of the radiation from the measurement beam is scattered in the direction of the illumination beam and focused by the lens onto the emitting surface of the laser diode, where it re-enters the laser cavity. This radiation re-entering the diode laser cavity causes a change in the laser gain, and thus in the intensity of the radiation emitted by the laser. This phenomenon is known as the self-mixing effect in diode lasers.

[0044] Variations in the intensity of radiation emitted by a laser, or of light waves in a laser cavity, can be detected by a photodiode or detector arranged to determine variations in impedance across the laser cavity. The diode or impedance detector converts the radiation variations into an electrical signal, and electronic circuitry is provided to process the electrical signal.

[0045] Figure 1 A simplified schematic diagram of a first VCSEL device 100 with an integrated photodiode is shown. The first VCSEL device 100 includes multiple VCSELs with integrated photodiodes arranged on a common substrate 110. The first VCSEL device 100 is a bottom emitter that emits laser light (indicated by arrows) through the substrate 110. Each of the VCSELs with an integrated photodiode includes a first DBR 115, an active layer 120, a first portion 135-1 of a second DBR, a second portion 135-2 of the second DBR, and a detector 140. Detector 140 includes at least one layer configured to detect changes in light waves within an optical resonator or laser cavity formed by the first and second DBRs 115, 135-1, 135-2, and a semiconductor layer sandwiched between the first and second DBRs 115, 135-1, 135-2. In this embodiment, the individual VCSELs are separated by oxidized openings 130, or trenches, which are then filled with an electrically isolating material. The oxidized opening 130 can be used, for example, to provide a current hole (not shown) in the first DBR 115 or the second DBR 135-1, 135-2. The VCSEL is electrically contacted by means of a first electric laser contact 105 and at least one second electric laser contact 127. In this embodiment, the first electric laser contact 105 electrically contacts a common current distribution layer (not shown) that is integrated into the non-etched portion of the first DBR 115 to provide current to all VCSELs included in the VCSEL array. The first VCSEL device 100 includes a plurality of second electric laser contacts 127, wherein each second electric laser contact 127 contacts a row of VCSELs included in the VCSEL array. These rows are arranged relative to each other. Figure 1 The first DBR 115 includes 30 pairs of layers with alternating refractive indices to provide a reflectivity of 98.5% so that laser emission can pass through the substrate 110. The first DBR 115 may, for example, include AlGaAs (AlGaAs) with different Al concentrations (e.g., varying between 15% and 90%). x Ga (1-x)As) layers to provide different refractive indices. The first portion 135-1 of the second DBR may include 30 pairs of layers with alternating refractive indices, and the second portion 135-2 of the second DBR may include another 20 pairs of layers with alternating refractive indices to provide sufficient reflectivity. The second portion 135-2 of the second DBR of each VCSEL mesa is covered by a first detector electrode 150, so that each detector 140 can be read by means of the corresponding second electro-laser contact 127 and the corresponding first detector electrode 150. A solder bump 160 is provided on top of each first detector electrode 150, so that the first VCSEL device 100 can be mounted in a flip-chip arrangement, for example, on top of a substrate (not shown), which may include evaluation circuitry for evaluating the measurement signals generated by the first VCSEL device 100.

[0046] Figure 2 Shown Figure 1 Schematic diagram of the electrical contact scheme of the first VCSEL device 100 shown in FIG. The VCSEL is electrically pumped by means of a current source 190, which is in contact with a common first electrical laser contact 105 and with second electrical laser contacts 127-1, 127-2, so that each row of a plurality of laser diodes 122 can be operated independently of the other rows. The second electrical laser contacts 127 and the first detector electrodes 150 are electrically connected to an analytical evaluation device (not shown), so that each detector 140 can be read separately to determine a self-mixing measurement signal.

[0047] Figure 3 A simplified schematic diagram shows a top view of a first VCSEL device 100 . The first VCSEL device 100 is electrically contacted by means of a common first electric laser contact 105 , second electric laser contacts 127 - 1 , 127 - 2 , . . . and solder bumps 160 .

[0048] Figure 4A simplified schematic diagram of a second VCSEL device 100 including a detector chip 144 is shown. In this embodiment, the second VCSEL device 100 includes a bottom-emitting VCSEL array including an optical resonator having a first DBR, a second DBR 135 and an active layer 120 sandwiched between the first DBR 115 and the second DBR 135. The active layer 120 typically includes one or several quantum well layers. A first electric laser contact 105 (typically an n-contact) is provided on the back side of the substrate 110 opposite to the side of the substrate 110 on which the optical resonator is provided. At least one second electric laser contact 127 (typically a p-contact) is provided on top of the second DBR 135. The first electric laser contact 105 and the second electric laser contact 127 are arranged to be able to provide an electrical drive current to the optical resonator (electrically pump the optical resonator). The VCSEL device 100 may include a VCSEL array not provided in FIG. Figure 4 Other layers, such as current distribution layers and current confinement layers, are not explicitly shown but are well known to those skilled in the art. The first electric laser contact 105 and the second electric laser contact 127 (each of which may comprise a metal layer) may surround an aperture through which laser light 10 may be emitted if a drive current above the laser threshold current of the VCSEL device 100 is supplied. The emission wavelength of the laser light 10 is above 900 nm, preferably above 930 nm, making the substrate 110 (GaAs) substantially transparent to the laser light 10. The VCSEL array of the VCSEL device 100 is mounted on a detector chip 144 using the second electrode 127. According to this embodiment, the detector chip 144 is arranged to provide electrical connections between the first electric laser contact 105 and the second electric laser contact (not shown). The detector chip 144 also includes a plurality of detectors 140 (e.g., photodiodes). The detectors 140 are aligned with the openings of the first electric laser contact 105 and the second electric laser contact 127. The reflectivity of the first DBR 115 and the second DBR 135 is arranged so that the laser light 10 is emitted through the substrate 110 and the optical device 170 (lens) etched in the substrate 110. The lens is arranged to focus the laser light 10 to the field of view. The laser beams are spread apart from each other by offsetting the lens relative to the center of the corresponding VCSEL. The reflectivity of the second DBR 135 is such that a limited amount of laser light is received by the corresponding detector 140 to determine the self-mixing interferometry signal. Each detector is electrically contacted with two contact pads 148 arranged on opposite sides of the detector chip 144. The contact pads 148 can enable the VCSEL device to be mounted, for example, on a PCB.

[0049] Figure 5FIG1 shows a schematic diagram of a third VCSEL device 100 with a detector chip 144. The third VCSEL device 100 includes an array of top-emitting VCSELs, each of which includes a first DBR 115, a second DBR 135, and an active layer 120 arranged between the first DBR 115 and the second DBR 135. In this case, the reflectivity of the second DBR 135 is slightly lower than the reflectivity of the first DBR 115. Therefore, most of the laser light 10 is emitted through the second electric laser contact body 127, which is, for example, a ring-shaped body. Figure 2 or Figure 3 Similar to what has been discussed, the second electric laser contact is arranged on top of the second DBR 135 to electrically contact the rows or columns of VCSELs comprised by the VCSEL array. The second electric laser contact 127 is electrically isolated relative to the first DBR 115 and the active layer 120 by means of an isolation structure 108 (e.g., an oxide layer). The first electric laser contact 105 is deposited on the back side of the substrate 110 opposite to the side of the substrate 110 on which the first DBR 115 and subsequently the layer stack of the active layer 120, the second DBR 135 and the second electric laser contact 127 are machined. The first electric laser contact 105 includes an opening aligned with the VCSEL so that the laser light 10 can be emitted through the substrate 110 through the corresponding opening. Alternatively, the substrate 110 can be partially removed to avoid absorption of the laser light 10 by the substrate 110. The third VCSEL device 100 is similar to the third VCSEL device 100 described with respect to FIG. Figure 4 The discussed similarly is mounted on a detector chip 144, which includes an electrical driver (not shown) that is arranged to be able to provide an electrical drive current to the VCSEL by means of the first electrical laser contact body 105 and the second electrical laser contact body 127. The detector chip 144 also includes a detector 140, wherein the detector 140 is aligned with the opening of the first electrical contact body 105. The detector chip 144 also includes an analysis and evaluation device 323, which is arranged to be able to receive a self-mixing interferometry measurement signal from the detector 140 to determine the distance to, for example, an object and thereby determine a three-dimensional image of the object. The third VCSEL device 100 also includes a common optical device 170. The common optical device 170 is integrated on the wafer level by means of a transparent material. The transparent material is deposited on top of the VCSEL. The transparent material is also shaped so that the laser light 10 emitted by different VCSELs is directed in different directions. The common optical device 170 may also include an integrated microlens (e.g. a structured layer of different transparent materials) that is arranged to focus the laser light 10. As discussed with respect to Figure 4 and Figure 5 The optical device discussed can also be compared with the Figure 1 The embodiments discussed are combined.

[0050] Figure 6 A cross-section of a self-mixing interferometer sensor 300 according to a first embodiment is shown. The self-mixing interferometer sensor 300 is configured to determine the presence, distance, and motion of an object using self-mixing interferometry. The optical sensor 300 includes the VCSEL device 100 discussed above, a transmissive window 310, and a driver circuit 320 for electrically driving the VCSEL device 100. The driver circuit 320 is electrically connected to the VCSEL device 100 to supply power to the VCSEL device 100 in a defined manner. The driver circuit 320 includes a memory device for storing data and instructions for operating the driver circuit 320, and a processing unit for executing the data and instructions for operating the driver circuit 320. The self-mixing interferometer sensor 300 also includes an analyzer / evaluator 323. The detectors 140 (e.g., photodiodes) included in the VCSEL device 100 are configured to determine changes in a standing wave pattern within a laser cavity coupled to the corresponding photodiode. The analyzer / evaluator 323 includes at least one memory device, such as a memory chip, and at least one processing device, such as a microprocessor. The analyzer evaluator 323 is adapted to receive electrical signals from the VCSEL device 100 and, optionally, from the driver circuit 320, to determine the distance or motion of one or more objects based on the interference of the laser light 10 reflected by the respective objects and the optical standing waves within the respective laser cavities. The analyzer evaluator may optionally be arranged to be able to reconstruct a 3D image of a scene illuminated by the self-mixing interferometric sensor 300.

[0051] Figure 7 A simplified schematic diagram of a mobile communication device 380 is shown that includes a self-mixing interferometry sensor 300. The self-mixing interferometry sensor 300 can be used, for example, in conjunction with a software application running on the mobile communication device 380. The software application can use the self-mixing interferometry sensor 300 for providing a 3D image or movie of a scene illuminated by means of the self-mixing interferometry sensor 300.

[0052] Figure 8A schematic diagram illustrates the process flow of a method for manufacturing a VCSEL device 100 according to the present invention. In step 410, a substrate 110 is provided. In step 415, a VCSEL array comprising a plurality of laser diodes is disposed on the substrate. Each laser diode includes an optical resonator. The optical resonator comprises a first distributed Bragg reflector, a second distributed Bragg reflector, and an active layer for emitting light. The active layer is disposed between the first distributed Bragg reflector 115 and the second distributed Bragg reflector. In step 420, a first electric laser contact is provided. The first electric laser contact 105 is a common contact for all laser diodes in the VCSEL. In step 425, at least one second electric laser contact is provided. The first electric laser contact and the at least one second electric laser contact are configured to provide an electrical drive current to electrically pump the optical resonator of the laser diode. The at least one second electric laser contact is also configured to electrically contact at least a subset of the plurality of laser diodes 122 in the VCSEL array. In step 430, a detector is provided. Each detector is arranged to generate an electrical self-mixing interferometry signal associated with the at least one laser diode upon receiving laser light.

[0053] The first DBR 115, the active layer 120, the second DBR 135 and the layers of the electrical contacts and any other layers as current injection layers etc. may be deposited by an epitaxial method such as MOCVD or MBE.

[0054] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive.

[0055] From reading this disclosure, other modifications will be apparent to persons skilled in the art.Such modifications may involve other features which are already known in the art and which may be used instead of or in addition to features already described herein.

[0056] Variations of the disclosed embodiments may be understood and effected by those skilled in the art by studying the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the singular form does not exclude a plurality of elements or steps. The fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0057] Any reference signs in the claims should not be construed as limiting the scope of the claims.

[0058] List of reference numerals:

[0059] 10 Laser

[0060] 100 VCSEL devices

[0061] 105 First electric laser contact body

[0062] 108 Isolation Structure

[0063] 110 matrix

[0064] 115 First DBR

[0065] 120 active layer

[0066] 122 Laser Diode

[0067] 127, 127-1, 127-2 Second electrical contact

[0068] 130 Oxidation opening

[0069] 135 Second DBR

[0070] 135-1 The first part of the second DBR

[0071] 135-2 The second part of the second DBR

[0072] 140 detector

[0073] 144 detector chip

[0074] 148 contact pads

[0075] 150 first detector electrode

[0076] 160 solder bumps

[0077] 170 Optical Device

[0078] 300 Self-mixing interferometric sensor

[0079] 310 Transmission Window

[0080] 320 drive circuit

[0081] 323 Analysis Evaluator

[0082] 380 Mobile communication devices

[0083] 410 Steps to set up the base

[0084] 415 Steps to Set Up a VCSEL Array

[0085] 420 Steps for setting the first electric laser contact body

[0086] 425 Steps for setting up a second electric laser contact body

[0087] 430 Steps to set up the detector

Claims

1. A vertical cavity surface emitting laser (VCSEL) device (100) of a self-mixing interferometric sensor (300) for recording three-dimensional images, the VCSEL device (100) comprising a VCSEL array, a plurality of detectors (140), a first electric laser contact (105) and at least one second electric laser contact (127), wherein: The VCSEL array comprises a plurality of laser diodes (122), wherein each laser diode (122) comprises an optical resonator, wherein the optical resonator comprises a first distributed Bragg reflector (115), a second distributed Bragg reflector (135) and an active layer (120) for emitting laser light (10), wherein the active layer (120) is arranged between the first distributed Bragg reflector (115) and the second distributed Bragg reflector (135), wherein the first electric laser contact (105) and the at least one second electric laser contact (127) are arranged to be capable of The invention relates to a method for providing an electrical drive current for electrically pumping an optical resonator of a laser diode (122), wherein the first electrical laser contact (105) is a common contact for all laser diodes (122) of a VCSEL array, wherein the at least one second electrical laser contact (127) is arranged to be able to make electrical contact with at least a subset of the plurality of laser diodes (122) of the VCSEL array, and wherein each detector (140) is arranged to be able to generate an electrical self-mixing interferometry signal associated with at least one laser diode (122) upon receiving laser light (10), wherein each of the plurality of detectors corresponds to a corresponding subset of the plurality of laser diodes (122), and is configured to receive laser light from at least one diode of the corresponding subset when the corresponding subset of the plurality of laser diodes emits laser light and a portion of the emitted laser light is reflected back to an optical resonator of the corresponding subset of the plurality of laser diodes, wherein electrical self-mixing interferometry signals generated by the plurality of detectors are used to record a three-dimensional image.

2. The VCSEL device (100) according to claim 1, wherein The plurality of laser diodes (122) includes at least 1000 laser diodes (122).

3. The VCSEL device (100) according to any one of the preceding claims, wherein The VCSEL device (100) comprises two, three, four or more second electrical laser contacts (127), wherein each second electrical laser contact (127) is arranged to be capable of electrically driving a respective subset of the laser diodes (122) of the VCSEL array.

4. The VCSEL device (100) according to claim 1 or 2, wherein: The VCSEL device (100) comprises a second electric laser contact (127), wherein the first electric laser contact (105) and the second electric laser contact (127) are arranged to provide a common electric drive current to all laser diodes (122) of the VCSEL array.

5. The VCSEL device (100) according to claim 1 or 2, wherein: Each detector (140) is arranged to receive laser light (10) from a corresponding laser diode (122).

6. The VCSEL device (100) according to claim 1 or 2, wherein: The detector (140) is integrated into the optical resonator.

7. The VCSEL device (100) according to claim 6, wherein: Each optical resonator includes a dedicated detector (140).

8. The VCSEL device (100) according to claim 7, wherein: Each detector (140) comprises a first detector electrode (150), wherein the first detector electrode (150) and at least one additional electrode are arranged to be able to read an electrical self-mixing interferometry signal.

9. The VCSEL device (100) according to claim 8, wherein: The at least one additional electrode comprises the first electric laser contact (105) or the at least one second electric laser contact (127).

10. The VCSEL device (100) according to claim 9, wherein: The at least one additional electrode is the at least one second electric laser contact (127), wherein the detector (140) is integrated in the second distributed Bragg reflector (135), wherein the VCSEL array is arranged such that during operation of the VCSEL device (100), laser light (10) is emitted by the VCSEL device (100) via the first distributed Bragg reflector (115).

11. The VCSEL device (100) according to claim 10, wherein: The VCSEL device (100) is arranged as a flip-chip device.

12. The VCSEL device (100) according to any one of claims 1, 2, and 7, wherein: The VCSEL array is mounted on a detector chip (144), wherein the detector chip (144) includes a detector (140).

13. The VCSEL device (100) according to any one of claims 1, 2, 7-11, wherein: The VCSEL device (100) comprises at least one optical device (170) arranged to redirect laser light (10).

14. The VCSEL device (100) according to any one of claims 1, 7 to 11, wherein: The plurality of laser diodes (122) includes at least 5,000 laser diodes (122).

15. The VCSEL device (100) according to any one of claims 1, 7 to 11, wherein: The plurality of laser diodes (122) includes at least 10,000 laser diodes (122).

16. A self-mixing interferometer sensor (300) for recording a three-dimensional image, comprising a VCSEL device (100) according to any one of claims 1 to 15, wherein: The three-dimensional self-mixing interference sensor (300) further comprises a driving circuit (320) and an analysis and evaluation device (323), wherein the driving circuit (320) is arranged to be able to electrically drive the laser diode (122) by means of the first electric laser contact body (105) and the at least one second electric laser contact body (127), wherein the analysis and evaluation device (323) is arranged to be able to analyze and evaluate the electric self-mixing interference measurement signal.

17. A method for manufacturing a vertical cavity surface emitting laser (VCSEL) device (100) for a self-mixing interferometric sensor (300) for recording three-dimensional images, the method comprising the following steps: providing a base body (110), A VCSEL array including a plurality of laser diodes (122) is provided on a substrate (110), wherein each laser diode (122) includes an optical resonator, wherein the optical resonator includes a first distributed Bragg reflector (115), a second distributed Bragg reflector (135) and an active layer (120) for emitting light, wherein the active layer (120) is arranged between the first distributed Bragg reflector (115) and the second distributed Bragg reflector (135). providing a first electric laser contact (105), wherein the first electric laser contact (105) is a common contact for all laser diodes (122) of the VCSEL array, At least one second electric laser contact (127) is provided, wherein the first electric laser contact (105) and the at least one second electric laser contact (127) are arranged to be capable of providing an electric drive current to electrically pump an optical resonator of a laser diode (122), wherein the at least one second electric laser contact (127) is arranged to be capable of making electrical contact with at least a subset of the plurality of laser diodes (122) of a VCSEL array, Detectors (140) are provided, wherein each detector (140) is arranged to generate an electrical self-mixing interferometry signal associated with at least one laser diode (122) upon receiving laser light (10), wherein each of the plurality of detectors corresponds to a corresponding subset of the plurality of laser diodes (122), and is configured to receive laser light from at least one diode of the corresponding subset when the corresponding subset of the plurality of laser diodes emits laser light and a portion of the emitted laser light is reflected back to an optical resonator of the corresponding subset of the plurality of laser diodes, wherein electrical self-mixing interferometry signals generated by the plurality of detectors are used to record a three-dimensional image.

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