Multi-channel light emission chip array based on asymmetric multi-quantum well technology and preparation method

Abstract

The invention provides a multichannel light emission chip array based on an asymmetric multi-quantum well technology, an asymmetric multi-quantum well layer is composed of compressive strain InGaAlAs quantum wells and tensile strain InGaAlAs quantum barriers, the compressive strain InGaAlAs quantum wells and the tensile strain InGaAlAs quantum barriers are distributed at intervals, and the light-emitting wavelengths of the compressive strain InGaAlAs quantum wells are gradually reduced from top to bottom to form an asymmetric structure; the grating layer is of an array structure composed of a plurality of gratings, a plurality of laser units are formed, the grating layer is manufactured by adopting a reconstruction equivalent chirp technology, a sampling grating structure with a uniform grating period is manufactured in each laser unit through holographic photoetching and ultraviolet lithography in sequence, and pi phase shift is arranged in the center of the sampling grating. The invention also provides a preparation method of the multi-channel light emission chip array. According to the invention, accurate control of emission wavelength can be realized, sufficient gain is provided for each laser unit through the quantum well with an asymmetric structure, the single-mode yield and transmission capacity are improved, the preparation difficulty of the grating is simplified, and the demand of emerging calculation application for the Internet transmission rate is met.

Description

Technical field:

[0001] The present invention belongs to the technical field of optoelectronic chips, and in particular relates to a multi-channel light emitting chip array based on an asymmetric multi-quantum well technology and a preparation method thereof. Background technology:

[0002] Emerging computing applications in artificial intelligence (AI) and machine learning (ML) are accelerating the demand for the Internet. To accommodate the massive growth of Internet traffic, integrated dense wavelength-division-multiplexed (DWDM) systems with advantages such as low power consumption, small size, and high reliability have been proposed. Multi-channel laser arrays play a vital role in DWDM communication systems and monolithic integrated optical circuits. Expanding the number of channels in multi-wavelength laser arrays is the most effective way to increase the transmission rate of DWDM. Currently, multi-channel semiconductor laser arrays have been widely studied. Several techniques, such as variable ridge width, selective area growth, nanoimprinting, and electron beam lithography, have been proposed for the preparation of laser arrays. However, these methods have their own limitations when manufacturing laser arrays with more than 100 channels. Varying ridge width deteriorates the single longitudinal mode characteristics of each channel. Selective area growth can only be used for quantum well materials or bulk materials, and the band gap difference between selective area growth materials and non-selective area growth materials is limited. Nanoimprinting has problems such as low device yield and poor uniformity of large-area imprint templates. Electron beam lithography faces challenges in ensuring uniform channel spacing. In addition, the above methods are all subject to the influence of the gain range, making it difficult to increase the number of channels.

[0003] In summary, the optimization of lasers can be considered from the following directions: first, precise control of wavelength and guarantee of single longitudinal mode (SLM) yield, and second, optimization design of active area materials to ensure sufficient gain of the required wavelength in the multi-channel laser array. Therefore, the present invention proposes a multi-channel light emitting chip array based on asymmetric multi-quantum well technology and a preparation method to solve the above problems. Summary of the invention:

[0004] The purpose of the present invention is to address the deficiencies of the prior art and provide a multi-channel light emitting chip array based on asymmetric multi-quantum well technology and a preparation method thereof. The asymmetric quantum well technology is used to broaden the gain range of the laser, and a larger number of laser units can be integrated on a single chip, thereby increasing the transmission capacity in the DWDM system. The reconstructed equivalent chirp technology is used to make a sampling grating for mode selection, and a π phase shift is introduced to improve the single-mode yield.

[0005] The present invention adopts the following technical solutions:

[0006] (I) The present invention provides a multi-channel light emitting chip array based on asymmetric multi-quantum well technology, wherein the multi-channel light emitting chip comprises an asymmetric multi-quantum well layer and a grating layer; the asymmetric multi-quantum well layer is composed of m compressively strained InGaAlAs quantum wells and n tensilely strained InGaAlAs quantum barriers, and the InGaAlAs quantum wells and InGaAlAs quantum barriers are distributed at intervals; the thickness and / or aluminum component of the compressively strained InGaAlAs quantum well gradually decreases from top to bottom, causing the photoluminescence wavelength of the chip to gradually decrease from top to bottom, forming an asymmetric structure; the grating layer is an array structure composed of a plurality of groups of gratings, forming a plurality of laser units.

[0007] Furthermore, the grating layer is manufactured by using a reconstruction equivalent chirp technology, and a sampled grating structure with a uniform grating period is manufactured in each laser unit by sequentially performing one holographic lithography and one ultraviolet lithography.

[0008] Furthermore, each laser unit is provided with a π phase shift structure, and the π phase shift structure is distributed at the center of the sampled grating, and phase matching is performed to ensure single wavelength output.

[0009] Furthermore, among the plurality of laser units, the sampling period of each laser unit is the same or different.

[0010] Furthermore, the number of the compressively strained InGaAlAs quantum wells is 3-5, and the number of the tensile strained InGaAlAs quantum barriers is 4-6.

[0011] Furthermore, in the array structure, the wavelength spacing between adjacent laser units is 0.8 or 1.6 nm.

[0012] Furthermore, the multi-channel light emitting chip also includes a substrate, a buffer layer, a lower limiting layer, an upper limiting layer, a corrosion barrier layer, a waveguide layer and a contact layer; the multi-channel light emitting chip is composed of a substrate, a buffer layer, a lower limiting layer, an asymmetric multi-quantum well layer, an upper limiting layer, a grating layer, a corrosion barrier layer, a waveguide layer and a contact layer stacked from bottom to top.

[0013] (II) The present invention also proposes a method for preparing a multi-channel light emitting chip array based on asymmetric multi-quantum well technology, comprising the following steps:

[0014] Step S1: sequentially growing a buffer layer, a lower confinement layer and an asymmetric multi-quantum well layer on the upper surface of the substrate by metal organic compound vapor deposition, and growing an upper confinement layer on the upper surface of the asymmetric multi-quantum well layer by metal organic compound vapor deposition;

[0015] Step S2: a sampling grating array structure with different sampling periods is manufactured above the upper confinement layer by one holographic lithography and one ultraviolet lithography, a π phase shift structure is introduced at the center of each sampling grating, and InP is deposited above the grating array to bury the grating layer;

[0016] Step S3: sequentially growing a corrosion barrier layer, a waveguide layer and a contact layer on the deposited InP grating layer;

[0017] Step S4: corroding the waveguide layer and the contact layer to form a ridge, and growing a front metal electrode in the ridge region above the contact layer;

[0018] Step S5: thinning and polishing the back side of the substrate, evaporating the back side electrode and heating to obtain an alloy, and cleaving the chip to obtain the multi-channel light emitting chip.

[0019] Beneficial effects of the present invention:

[0020] (1) The present invention is based on a multi-channel light emitting chip array of asymmetric multi-quantum well technology, and realizes precise control of emission wavelength by preparing a sampled grating array through equivalent reconstruction chirp technology, and ensures single-mode yield by introducing π phase shift at the center of the grating during grating production. For a multi-channel laser array, the same quantum well layer of different laser units, the quantum well of the asymmetric structure provides sufficient gain for each laser unit.

[0021] (2) The present invention uses asymmetric quantum well technology to broaden the gain range of the laser, increase the number of lasers that can be integrated, and select the lasing wavelength by reconstructing the equivalent chirp technology to make a sampling grating, and use π phase shift for phase matching to ensure single wavelength output. Gain is provided for a sufficient number of laser units, the density of monolithic integration is improved, making it advantageous for application in DWDM systems, increasing transmission capacity, simplifying the difficulty of grating preparation, and improving single-mode yield, meeting the requirements of emerging computing applications for Internet transmission rates. Description of the drawings:

[0022] Figure 1 It is a schematic diagram of the asymmetric multi-quantum well layer structure of the present invention;

[0023] Figure 2 It is a schematic diagram of a multi-channel light emitting chip based on asymmetric multi-quantum well technology, wherein electrode represents an electrode, WG represents a waveguide layer, BG represents a grating layer, p-InP represents an upper confinement layer, SCH-AMQW represents an asymmetric multi-quantum well layer, and n-InP represents a lower confinement layer;

[0024] Figure 3 It is a flow chart of the preparation of the sampling grating of the laser unit;

[0025] Figure 4It is a multi-channel light emitting chip where each laser unit samples the grating;

[0026] Figure 5 It is a schematic diagram of the sampling period of the sampling grating of each laser unit of the multi-channel light emitting chip;

[0027] Figure 6 It is a schematic diagram of the gain spectrum range of symmetric quantum well and asymmetric quantum well structures;

[0028] Figure 7 It is a spectrum diagram of a multi-channel light emission chip based on asymmetric multi-quantum well technology with 150 channels and an interval of 100 GHz according to the present invention. Specific implementation method:

[0029] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0030] Example 1

[0031] Reference Figures 1-2 The present invention provides a multi-channel light emitting chip based on asymmetric multi-quantum well technology. The multi-channel light emitting chip is composed of a substrate, a buffer layer, a lower confinement layer, an asymmetric multi-quantum well layer, an upper confinement layer, a grating layer, a corrosion barrier layer, a waveguide layer and a contact layer stacked from bottom to top.

[0032] In this embodiment, refer to Figure 1 The asymmetric multi-quantum well layer is composed of 5 compressively strained InGaAlAs quantum wells and 6 tensile strained InGaAlAs quantum barriers, and the InGaAlAs quantum wells and InGaAlAs quantum barriers are distributed at intervals, and the InGaAlAs quantum barriers distributed at the top and bottom are wrapped by confining heterostructures respectively. The thickness and / or aluminum component of the 5 compressively strained InGaAlAs quantum wells gradually decreases from top to bottom, and the emission wavelength gradually decreases from top to bottom, forming an asymmetric structure. Figure 1 The emission wavelengths of the five compressively strained InGaAlAs quantum wells are 1.55μm, 1.53μm, 1.51μm, 1.49μm and 1.47μm from top to bottom. The asymmetric multi-quantum well layer increases the gain range of the light-emitting chip and provides sufficient gain for the light-emitting chip with multiple channels to enable lasing.

[0033] Reference Figure 2In this embodiment, the grating layer is an array structure composed of 150 groups of gratings, forming 150 laser units, and the spacing between adjacent laser units is 0.8nm. The grating layer is made by reconstructing equivalent chirp technology, and a sampling grating structure with uniform grating period is made in each laser unit through one holographic lithography and one ultraviolet lithography in turn. Among the 150 laser units, the sampling period of each laser unit is the same or different, and different sampling periods can achieve different lasing wavelengths. Therefore, the sampling period of each laser unit can be determined according to the required lasing wavelength and prepared by lithography. The +1 level of the grating is used as the main mode to select the lasing wavelength. A π phase shift structure is set in the sampling grating of each laser unit. The π phase shift structure is distributed in the center of the sampling grating, and phase matching is performed to ensure single wavelength output.

[0034] The multi-channel light emitting chip array based on asymmetric multi-quantum well technology described in this embodiment adopts asymmetric quantum well technology to broaden the gain range, utilizes reconstruction equivalent chirp technology to prepare a sampled grating structure, and further selects the lasing wavelength, and the sampled grating utilizes the +1 level of the grating as the main mode to select the lasing wavelength.

[0035] Example 2

[0036] The embodiment of the present invention provides a method for manufacturing a multi-channel light emitting chip based on asymmetric multi-quantum well technology as described in Embodiment 1, comprising the following steps:

[0037] Step S1: sequentially growing a buffer layer and a lower confinement layer on the upper surface of a substrate by metal organic compound vapor deposition.

[0038] Step S2: depositing an asymmetric multi-quantum well layer on the lower confinement layer, the asymmetric multi-quantum well layer consisting of 5 compressively strained InGaAlAs quantum wells and 6 tensile strained InGaAlAs quantum barriers, and the InGaAlAs quantum wells and the InGaAlAs quantum barriers are distributed at intervals, and the InGaAlAs quantum barriers distributed at the top and bottom are wrapped by confining heterostructures respectively, and the luminescence wavelengths of the 5 compressively strained InGaAlAs quantum wells gradually decrease from top to bottom, forming an asymmetric structure.

[0039] Step S3: growing an upper confinement layer on the upper surface of the asymmetric multi-quantum well layer by metal organic compound vapor deposition.

[0040] Step S4: A sampling grating array structure with different sampling periods is manufactured on the upper limiting layer by one holographic lithography and one ultraviolet lithography.

[0041] Reference Figure 3First, a holographic lithography is performed to produce a uniform grating with a grating period of Λ0, and then ultraviolet lithography is performed to sample the uniform grating, using the +1 order of the grating as the main laser lasing mode, and introducing an equivalent π phase shift in each laser unit to achieve stable single-mode characteristics. The +1 order grating period of the laser is determined by the uniform grating period and the sampling period, as shown in the following formula:

[0042]

[0043] Where Λ0 represents the uniform grating period of holographic lithography, Λ +1 represents the +1-order grating period after UV lithography, and p represents the sampling period of the grating.

[0044] Step S5: InP is deposited above the grating array to bury the grating layer, and a corrosion barrier layer, a waveguide layer and a contact layer are sequentially grown on the deposited InP grating layer.

[0045] Step S6: The waveguide layer and the contact layer are corroded to form a ridge, and a front metal electrode is grown in the ridge region above the contact layer.

[0046] Step S7: thinning and polishing the back side of the substrate, evaporating the back side electrode and heating to obtain an alloy, and cleaving the chip to obtain the multi-channel light emitting chip.

[0047] The present invention manufactures a parallel multi-channel light emission chip array by changing the period of the sampling grating, different sampling periods correspond to different lasing wavelengths and use π phase shift to ensure single wavelength output.

[0048] The present invention is based on a multi-channel light emitting chip array of asymmetric multi-quantum well technology. The sampling grating array is prepared by equivalent reconstruction chirp technology to achieve precise control of the emission wavelength. The single-mode yield is guaranteed by introducing π phase shift at the center of the grating during grating production, and the gain range is increased by asymmetric quantum well technology. For a multi-channel laser array, the same quantum well layer of different laser units and the quantum well of the asymmetric structure provide sufficient gain for each laser unit. A parallel multi-channel light emitting chip array is produced by changing the period of the sampling grating. Different sampling periods correspond to different lasing wavelengths and π phase shift is used to ensure single wavelength output to improve the single-mode yield.

[0049] Effect test:

[0050] (1) Gain range

[0051] Test method: The mode gain range of a conventional laser and a laser with an asymmetric quantum well was simulated at a current of 120 mA using crosslight software.

[0052] Test results see Figure 6 ,Depend on Figure 6 It can be seen that the gain range of conventional lasers is only 50nm, while the gain range of asymmetric quantum well lasers is increased to 120nm, which provides a possibility for its application in dense wavelength division multiplexing technology.

[0053] (2) Precise control of emission wavelength

[0054] Using one holographic lithography and one ultraviolet light, after development, etching, and degumming, a grating with an equivalent structure is formed ( Figure 3 and Figure 4 ).Depend on Figures 3 to 5 It can be seen that the equivalent grating period determines the lasing wavelength. The lasing wavelength can be controlled by controlling the change of the grating period. The grating period increases from 1.8 to 5.2 μm, and a 150-channel laser array with a wavelength interval of 0.8 nm can be obtained within a wavelength range of 120 nm.

[0055] The spectrum was recorded and analyzed using an AQ6370 spectrum analyzer at 25°C with a bias current of 120mA. Figure 7 ,Depend on Figure 7 It can be seen that the wavelength range of the laser array is from 1464.23 to 1584.43nm, and the designed wavelength spacing is 0.8nm. The 150 channels cover a wavelength range of 120.2nm, and all channels are lasing in a single longitudinal mode. Compared with the prior art, the multi-channel light emitting chip array based on asymmetric multi-quantum well technology provided by the present invention is a multi-channel laser array with the highest monolithic integration and a higher single longitudinal mode rate.

[0056] The above are only preferred implementations of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A multi-channel light emitting chip array based on asymmetric multi-quantum well technology, characterized in that: The multi-channel light emitting chip comprises an asymmetric multi-quantum well layer and a grating layer; The asymmetric multi-quantum well layer is composed of m compressively strained InGaAlAs quantum wells and n tensilely strained InGaAlAs quantum barriers, and the InGaAlAs quantum wells and InGaAlAs quantum barriers are spaced and distributed; The thickness and / or aluminum component of the compressively strained InGaAlAs quantum well gradually decreases from top to bottom; The grating layer is an array structure composed of several groups of gratings, forming several laser units.

2. The multi-channel light emitting chip array based on asymmetric multi-quantum well technology according to claim 1, characterized in that: The grating layer is manufactured by using a reconstruction equivalent chirp technology, and a sampling grating structure with a uniform grating period is manufactured in each laser unit by sequentially performing one holographic lithography and one ultraviolet lithography.

3. The multi-channel light emitting chip array based on asymmetric multi-quantum well technology according to claim 2, characterized in that: Each laser unit is provided with a π phase shift structure, and the π phase shift structure is distributed at the center of the sampled grating.

4. The multi-channel light emitting chip array based on asymmetric multi-quantum well technology according to claim 2, characterized in that: Among the plurality of laser units, the sampling period of each laser unit is the same or different.

5. The multi-channel light emitting chip array based on asymmetric multi-quantum well technology according to claim 1, characterized in that: The number of the compressive strain InGaAlAs quantum wells is 3-5, and the number of the tensile strain InGaAlAs quantum barriers is 4-6.

6. The multi-channel light emitting chip array based on asymmetric multi-quantum well technology according to claim 1, characterized in that: In the array structure, the wavelength spacing between adjacent laser units is 0.8 or 1.6 nm.

7. The multi-channel light emitting chip array based on asymmetric multi-quantum well technology according to claim 3, characterized in that: The multi-channel light emitting chip further comprises a substrate, a buffer layer, a lower limiting layer, an upper limiting layer, a corrosion barrier layer, a waveguide layer and a contact layer; The multi-channel light emitting chip is formed by stacking a substrate, a buffer layer, a lower limiting layer, an asymmetric multi-quantum well layer, an upper limiting layer, a grating layer, a corrosion barrier layer, a waveguide layer and a contact layer in sequence from bottom to top.

8. The method for preparing a multi-channel light emitting chip array based on asymmetric multi-quantum well technology according to claim 7, characterized in that: The following steps are involved: Step S1: sequentially growing a buffer layer, a lower confinement layer and an asymmetric multi-quantum well layer on the upper surface of the substrate by metal organic compound vapor deposition, and growing an upper confinement layer on the upper surface of the asymmetric multi-quantum well layer by metal organic compound vapor deposition; Step S2: a sampling grating array structure with different sampling periods is manufactured above the upper confinement layer by one holographic lithography and one ultraviolet lithography, a π phase shift structure is introduced at the center of each sampling grating, and InP is deposited above the grating array to bury the grating layer; Step S3: sequentially growing a corrosion barrier layer, a waveguide layer and a contact layer on the deposited InP grating layer; Step S4: corroding the waveguide layer and the contact layer to form a ridge, and growing a front metal electrode in the ridge region above the contact layer; Step S5: thinning and polishing the back side of the substrate, evaporating the back side electrode and heating to obtain an alloy, and cleaving the chip to obtain the multi-channel light emitting chip.

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