VCSEL coherent array chip based on gain guiding

Abstract

The application discloses a VCSEL coherent array chip based on gain guiding, which comprises a VCSEL array unit and a photonic crystal; the active layer of the VCSEL array unit is internally provided with the photonic crystal, and the distribution of the photonic crystal satisfies that the emission wavelength of the VCSEL array unit is just located in the photonic forbidden band of the photonic crystal; the channel position of the VCSEL array unit is not provided with the photonic crystal, so as to generate a defect on a topological structure and cause the difference of the refractive index at the position. The application utilizes the defect state of the photonic crystal to make the outgoing light of the laser emission unit be injected into the active layer of the adjacent laser emission unit along the defect of the photonic crystal, so that the particles in the active layer are subjected to stimulated radiation, and the laser with the same phase as the original VCSEL unit is generated, thereby realizing the coherence of the whole array.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor laser, in particular to a VCSEL coherent array chip based on gain guiding. BACKGROUND

[0002] Vertical cavity surface emitting lasers are widely used, including military, medical, printing, communication, computer, industrial processing, etc. With the development of technology and market, new applications, new functions of consumer electronics, automotive, and industrial fields such as laser radar and 3D sensing require smaller devices, higher power and beam quality. VCSEL coherent array, a new laser technology, makes this possible.

[0003] VCSEL coherent array can increase the number of array units to improve light output power, and reduce the far-field divergence angle through coherence to improve beam quality. Realizing high-power semiconductor laser becomes a reality, and now high-power semiconductor laser has reached hundreds of watts.

[0004] Because semiconductor laser array involves multiple lasers, the coherence between the emitted light is poor, which cannot meet the actual demand. SUMMARY

[0005] In view of the above problems in the prior art, the present application provides a VCSEL coherent array chip based on gain guiding.

[0006] The present application discloses a VCSEL coherent array chip based on gain guiding, comprising: a VCSEL array unit and a photonic crystal.

[0007] The active layer of the VCSEL array unit is provided with the photonic crystal inside, and the distribution of the photonic crystal satisfies that the emission wavelength of the VCSEL array unit is just located in the photonic band gap of the photonic crystal.

[0008] The VCSEL array unit is not provided with a photonic crystal at the channel position, so as to produce a defect in the topological structure and cause the difference in refractive index at this position.

[0009] As a further improvement of the present application, the active layer of the VCSEL array unit is connected, and the defect state of the photonic crystal is used to inject the emitted light of the laser emission unit into the active layer inside the adjacent laser emission unit.

[0010] As a further improvement of the present application, the light injected into the adjacent laser emission unit will cause the particles inside the injected laser emission unit to be stimulated to emit laser with the same phase as the original VCSEL unit, so as to realize the coherence of the whole array.

[0011] As a further improvement of the present application, the VCSEL array unit comprises, from top to bottom, a P-face metal electrode and a passivation layer, a P-type distributed Bragg reflector, an oxidation confinement layer, a cavity layer, an active layer with a photonic crystal, a cavity layer, an N-type distributed Bragg reflector, a substrate and an N-face metal electrode; wherein the P-face metal electrode and the passivation layer are of a same layer structure, and a light transmission hole is formed in the middle of the oxidation confinement layer.

[0012] As a further improvement of the present application, the VCSEL coherent array chip is applicable to light in a wavelength band of 450nm-2μm.

[0013] As a further improvement of the present application, the material of the substrate comprises one of GaAs, InP, GaN and Si.

[0014] As a further improvement of the present application, the N-type distributed Bragg reflector or the P-type distributed Bragg reflector is composed of a double-layer semiconductor structure of GaAs / AlGaAs or a dielectric film structure of SiO2 / Si3N4. x Ga (1-x) As / Al y Ga (1-y) As of a double-layer semiconductor structure or a dielectric film structure of SiO2 / Si3N4.

[0015] As a further improvement of the present application, the P-type distributed Bragg reflector is a semi-transparent and semi-reflective mirror, which is composed of 20-30 pairs of double-layer structures and has a reflectivity of more than 99%.

[0016] As a further improvement of the present application, the N-type distributed Bragg reflector is a full reflective mirror, which is composed of 30-40 pairs of double-layer structures and has a reflectivity of more than 99.9%.

[0017] As a further improvement of the present application, the photonic crystal can realize the regulation of refractive index by internally filling materials such as SiO2 / Si3N4.

[0018] As a further improvement of the present application, the VCSEL coherent array chip can be applied to the preparation of a high-power coherent laser, and the VCSEL coherent array chip can make the secondary laser emission unit emit laser by a time delay circuit.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] The present application utilizes the defect state of the photonic crystal to make the outgoing light of the primary laser emission unit enter the adjacent laser emission unit along the defect of the photonic crystal, so that the internal particles of the adjacent laser emission unit emit stimulated radiation, realize injection locking, and emit light coherent with the light emitted by the primary laser unit, thereby making the whole array output coherent light; the present application utilizes the defect state of the photonic crystal and pumps to excite other laser emission units to emit coherent light, thereby realizing the coherence of the whole laser array. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A front view structural schematic diagram of a VCSEL coherent array chip based on gain guiding according to an embodiment of the present application is disclosed.

[0022] Figure 2 A top view structural schematic diagram of a VCSEL coherent array chip based on gain guiding according to an embodiment of the present application is disclosed.

[0023] Figures 3-6 A schematic diagram in a preparation method of a VCSEL coherent array chip based on gain guiding according to an embodiment of the present application is disclosed.

[0024] In the drawings:

[0025] 1, substrate; 2, N-type distributed Bragg reflector; 3, cavity layer; 4, active layer; 5, photonic crystal; 6, P-type distributed Bragg reflector; 7, passivation layer; 8, oxidation layer; 9, P-face metal electrode; 10, N-face metal electrode. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0027] The present application will be described in further detail below in conjunction with the drawings:

[0028] As shown in Figure 1 , 2 , the present application provides a VCSEL coherent array chip based on gain guiding, comprising: a VCSEL array unit and a photonic crystal 5; wherein,

[0029] The active layer of the VCSEL array unit is internally provided with the photonic crystal 5, and the distribution of the photonic crystal 5 satisfies that the emission wavelength of the VCSEL array unit is exactly located in the photonic band gap of the photonic crystal; at the same time, the photonic crystal 5 is not arranged at the channel position of the VCSEL array unit, so as to produce a defect in the topological structure and cause the difference of the refractive index at this position.

[0030] The active layer of the VCSEL array unit of the present application is connected, and the defect state of the photonic crystal 5 is used to inject the light emitted by the laser emitting unit into the active layer of the adjacent laser emitting unit along the defect of the photonic crystal. At the same time, the light injected into the adjacent laser emitting unit will cause the particles injected into the laser emitting unit to be stimulated to emit laser with the same phase as the original VCSEL unit, so as to realize the coherence of the whole array.

[0031] Specifically,

[0032] The VCSEL array unit of the present application comprises, from top to bottom, a P-face metal electrode 9 and a passivation layer 7 (the P-face metal electrode 9 and the passivation layer 7 are a same layer structure), a P-type distributed Bragg reflector 6, an oxidation confinement layer 8 (a light transmission hole is formed in the middle of the oxidation confinement layer 8), an upper cavity layer 3, an active layer 4 with a photonic crystal 5, a lower cavity layer 3, an N-type distributed Bragg reflector 2, a substrate 1 and an N-face metal electrode 10. Among them,

[0033] The N-type distributed Bragg reflector 2 is grown on the top of the substrate 1, the lower cavity layer 3 is grown on the N-type distributed Bragg reflector 2, the active layer 4 is grown on the lower cavity layer 3, the photonic crystal 5 is etched in the active layer 4, the upper cavity layer 3 is on the active layer 4, the oxidation confinement layer 8 with a light transmission hole is grown above the upper cavity layer 3, the P-type distributed Bragg reflector 6 is grown above the oxidation confinement layer 8, the oxidation confinement layer 8 and the P-type distributed Bragg reflector 6 form the array unit layer, and the passivation layer 7 is grown above the P-type distributed Bragg reflector 6; the P-face metal electrode 9 is sputtered above the passivation layer 7, and the N-face metal electrode 10 is sputtered below the bottom (light emitting side) of the substrate 1.

[0034] Further,

[0035] The VCSEL coherent array chip is suitable for 450nm-2μm band light.

[0036] The material of the substrate 1 includes semiconductor materials such as GaAs, InP, GaN or Si.

[0037] The N-type distributed Bragg reflector 2 or the P-type distributed Bragg reflector 6 is composed of a double-layer semiconductor structure of Al x Ga (1-x) As / Al y Ga (1-y) As or a SiO2 / Si3N4 dielectric film structure.

[0038] The P-type distributed Bragg reflector 6 is a semi-transparent and semi-reflective mirror, which is composed of 20-30 pairs of double-layer structures and has a reflectivity of more than 99%.

[0039] The N-type distributed Bragg reflector 2 is a full reflector, which is composed of 30-40 pairs of double-layer structures, and the reflectivity is above 99.9%.

[0040] The air cavity of the photonic crystal 5 can be filled with SiO2 / Si3N4 and other materials to realize the refractive index control.

[0041] The VCSEL coherent array chip can be applied to the preparation of a high-power coherent laser, and the VCSEL coherent array chip can make the secondary emission unit emit laser through a time delay circuit.

[0042] The application provides a preparation method of a VCSEL coherent array chip based on gain guiding, which comprises the following steps:

[0043] Step 1: an N-type distributed Bragg reflector 2, a lower cavity layer 3 and an active layer 4 are epitaxially grown on a substrate 1 by using a plasma enhanced chemical vapor deposition (PECVD) method, and a periodic photonic crystal 5 is formed in the active layer 4 by using electron beam exposure and etching, as shown in Figure 2 、 3 as shown in

[0044] Step 2: an upper cavity layer 3 and a P-type distributed Bragg reflector 6 are epitaxially grown on the active layer 4 by using a plasma enhanced chemical vapor deposition (PECVD) method, as shown in Figure 4 .

[0045] Step 3: the VCSEL to be cleaned is cleaned according to the RCA standard, the chip is dried by blowing high-purity nitrogen after cleaning, and then the epitaxial wafer to be processed is heated and dried for use.

[0046] Step 4: a mesa is made, as shown in Figure 5 .

[0047] Firstly, a certain thickness of SiO2 mask is deposited or sputtered on the epitaxial wafer to be processed, then a SiO2 mesa mask is made by using photoetching and etching technology, a mesa structure is etched on the chip by using a dry etching method, the excess SiO2 is removed by chemical etching, and the chip is cleaned; after cleaning, the epitaxial wafer to be processed is dried by blowing high-purity nitrogen, and then the wafer is heated and dried for use.

[0048] Step 5: an oxidation limiting layer 8 is made

[0049] The oxidation limiting layer 8 in the annular epitaxial wafer mesa is formed by using a wet selective oxidation technology, and after oxidation, the chip is taken out for use.

[0050] Step 6: a passivation layer 7 is prepared

[0051] Depositing or sputtering a certain thickness of insulating material as passivation layer 7 on the epitaxial wafer, exposing electrode holes by using photoetching and etching technology, for packaging, as shown in Figure 6

[0052] Step 7, making P-face metal electrode 9:

[0053] Coating photoresist on the epitaxial wafer, making electrode pattern by photoetching and developing, sputtering metal, and stripping to form P-face metal electrode 9, for packaging;

[0054] Step 8, processing substrate 1:

[0055] Using thinning technology to thin the substrate 1 to a suitable thickness for subsequent processing;

[0056] Step 9, making N-face metal electrode 10, as shown in Figure 1

[0057] Again using double-sided overlay process, coating photoresist, making electrode pattern by photoetching and developing, sputtering metal, and stripping to form N-face metal electrode 10, for final packaging;

[0058] Step 10, cleaving and packaging:

[0059] Cleaving the chip and completing the packaging of the chip by using hot-press welding.

[0060] The advantages of the present application are:

[0061] The present application utilizes the periodicity and defect state of photonic crystal. The periodically distributed photonic crystal satisfies the emission wavelength of the VCSEL unit, which is just in the photonic band gap of the photonic crystal, and cannot propagate inside the photonic crystal. The defect in the topological structure causes the difference in refractive index, so that the outgoing light of the laser emission unit is injected into the active layer of the adjacent laser emission unit along the defect of the photonic crystal. The light injected into the laser emission unit will cause the particles inside the injected laser emission unit to be stimulated to radiate, producing laser with the same phase as the original VCSEL unit, thereby realizing the coherence of the entire array.

[0062] The above is only the preferred embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.​​

Claims

1. A gain-guided based VCSEL coherent array chip, characterized in that, The application relates to a VCSEL coherent array chip. The VCSEL array unit is internally provided with a photonic crystal, the distribution of the photonic crystal meets the requirement that the emission wavelength of the VCSEL array unit is just located in the photonic forbidden band of the photonic crystal. The VCSEL array unit is not provided with a photonic crystal at the channel position to generate a defect in the topological structure and cause the difference of the refractive index. The active layer of the VCSEL array unit is connected, the defect state of the photonic crystal is used to inject the outgoing light of the laser emission unit into the active layer of the adjacent laser emission unit along the defect of the photonic crystal. The light injected into the adjacent laser emission unit causes the particles in the injected laser emission unit to be stimulated to radiate the laser with the same phase as the original VCSEL unit to realize the coherence of the whole array. The VCSEL coherent array chip comprises, from top to bottom, a P-face metal electrode and a passivation layer, a P-type distributed Bragg reflector, an oxidation limiting layer, a cavity layer, an active layer with a photonic crystal, a cavity layer, an N-type distributed Bragg reflector, a substrate and an N-face metal electrode; wherein the P-face metal electrode and the passivation layer are in the same layer structure, and the middle part of the oxidation limiting layer is formed with a light transmission hole.

2. The gain-guided based VCSEL coherent array chip of claim 1, wherein, The VCSEL coherent array chip is applicable to the light in the 450nm-2mu wave band.

3. The gain-guided VCSEL coherent array chip based on gain steering according to claim 2, characterized in that, The material of the substrate comprises one of GaAs, InP, GaN and Si.

4. The gain-guided VCSEL coherent array chip based on gain steering according to claim 2, wherein, The P-type distributed Bragg reflector is a semi-transparent and semi-reflective mirror, which is composed of 20-30 pairs of double-layer structures and has a reflectivity of more than 99%.

5. The gain-guided VCSEL coherent array chip based on gain steering according to claim 2, wherein, The N-type distributed Bragg mirror or P-type distributed Bragg mirror is composed of double-layer semi-conductive structure of Al x Ga (1-x) As / Al y Ga (1-y) SiO2 / Si3N4 dielectric film structure.

6. The gain-guided VCSEL coherent array chip based on gain steering according to claim 2, wherein, The N-type distributed Bragg reflector is a full reflective mirror, which is composed of 30-40 pairs of double-layer structures and has a reflectivity of more than 99.9%.

7. The gain-guided VCSEL coherent array chip based on gain steering according to claim 2, wherein, The photonic crystal can realize the refractive index regulation by internally filling SiO2 / Si3N4 materials.

8. The gain-guided VCSEL coherent array chip based on gain steering according to claim 2, wherein, ​

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