On-chip integrated quantum cascade laser optical frequency comb and preparation method thereof

Abstract

The invention relates to the technical field of photon integration, in particular to an on-chip integrated quantum cascade laser optical frequency comb and a preparation method thereof. The quantum cascade laser optical frequency comb comprises a silicon waveguide and a quantum cascade laser integrated on the silicon waveguide through a micro transfer printing technology. A fundamental mode of an active area waveguide of the quantum cascade laser is coupled with a fundamental mode of a silicon waveguide to excite an antisymmetric mode, and the antisymmetric mode has the characteristic of small negative dispersion, so that regulation and control of dispersion in a quantum cascade laser cavity can be realized, and generation of an optical frequency comb can be realized. According to the invention, efficient integration of the quantum cascade laser on the silicon waveguide is realized, accurate regulation and control of dispersion of the quantum cascade laser can be realized through integration of micro transfer printing and the silicon waveguide, and a solid dispersion basis is provided for generation of an optical frequency comb of the quantum cascade laser. And the quantum cascade laser subjected to micro transfer printing is of a buried structure, so that the heat dissipation performance is improved.

Description

Technical Field

[0001] The present invention relates to the field of photon integration technology, and more specifically, to an on-chip integrated quantum cascade laser optical frequency comb and a preparation method thereof. Background Art

[0002] Quantum cascade lasers generate photons through transitions between subbands in the quantum wells of the active region. By adjusting the quantum well width, the energy levels between subbands can be tuned, thereby flexibly adjusting the wavelength of the output light. After years of development, quantum cascade lasers have been able to cover the entire mid-infrared band and have strong nonlinear effects in their cavities, such as four-wave mixing, which can directly excite quantum cascade laser optical frequency combs. Quantum cascade laser optical frequency combs have the advantages of wide spectrum and mid-infrared band, and show great potential in applications such as dual optical frequency comb sensing. Therefore, how to efficiently generate quantum cascade laser optical frequency combs has become a hot topic in current research. Studies have shown that an important condition for generating quantum cascade laser optical frequency combs is that the intracavity group velocity dispersion needs to be flat and have a small negative value. However, the group velocity dispersion in the quantum cascade laser cavity usually cannot meet this requirement, so a dispersion compensation mechanism must be introduced to adjust the dispersion in the cavity. Realizing dispersion compensation and exciting optical frequency combs has important scientific significance and practical application value.

[0003] At present, dispersion compensation of quantum cascade laser frequency comb can be achieved in the following ways: (1) GTI reflector: by coating a specific film system on the end face of the quantum cascade laser resonator, different wavelengths can take different paths (delays), thereby achieving dispersion compensation. The disadvantage is that the introduced film material has absorption loss and the coating process is relatively complicated. (2) Chirped Bragg grating: as the reflector of the quantum cascade laser resonator, the reflection delay of different wavelengths is controlled by adjusting the width and period of the grating, thereby achieving dispersion compensation. The advantages are high compensation efficiency and simple design, but the process requirements are high and a fine grating structure is required. (3) Waveguide geometry adjustment: by optimizing the geometric structure such as the width and thickness of the active area optical waveguide, small negative dispersion can be achieved under specific dimensions. The advantage is simple design, but because the thickness of the active area cannot be adjusted, the dispersion adjustment ability is limited. Sometimes even if the width is increased, the dispersion cannot be adjusted to a small negative value. (4) Excite coupled mode for dispersion regulation: By coupling the active region optical waveguide with the passive waveguide, an antisymmetric mode is excited. This mode has dispersion characteristics different from the fundamental mode, usually with small negative dispersion, and can be used for dispersion regulation. The advantage is that the design is simple, but an additional layer of passive waveguide needs to be grown under the active region.

[0004] In summary, the current dispersion compensation technologies for quantum cascade laser frequency combs have their own advantages and disadvantages. How to achieve reliable design, simple process and feasible solutions is still a topic worthy of in-depth study. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiency of the prior art that it is unable to achieve efficient dispersion regulation under the premise of simple structure and process, and to provide an on-chip integrated quantum cascade laser optical frequency comb and a preparation method thereof, which has a simple structure, a simple production process, and can achieve efficient dispersion regulation.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] Provided is an on-chip integrated quantum cascade laser optical frequency comb, comprising a silicon waveguide and a quantum cascade laser integrated on the silicon waveguide by micro-transfer printing technology; the fundamental mode of the waveguide in the active region of the quantum cascade laser is coupled with the fundamental mode of the silicon waveguide to excite an antisymmetric mode, the antisymmetric mode has the characteristic of small negative dispersion, can realize the regulation of the dispersion in the quantum cascade laser cavity, and realize the generation of an optical frequency comb.

[0008] The present invention discloses an on-chip integrated quantum cascade laser optical frequency comb, which realizes efficient regulation of the dispersion generated by the optical frequency comb by integrating the quantum cascade laser with a passive platform by micro-transfer printing, and the integration with the passive platform can further expand the application scenarios of the quantum cascade laser. Among them, the micro-transfer printing technology is used to extract the processed quantum cascade laser through a stamp and transfer it to the processed silicon waveguide. The active region waveguide fundamental mode of the quantum cascade laser is coupled with the silicon waveguide fundamental mode to excite an antisymmetric mode with a small negative dispersion characteristic to achieve the generation of an optical frequency comb; the antisymmetric mode has a small negative dispersion and can provide efficient dispersion compensation for the generation of the optical frequency comb; the dispersion of the antisymmetric mode is excited by integrating the quantum cascade laser with the silicon waveguide by micro-transfer printing, thereby providing a dispersion basis for the generation of the optical frequency comb. The present invention realizes the efficient integration of quantum cascade lasers on silicon waveguides. The precise control of the dispersion of quantum cascade lasers can be achieved through the integration of micro-transfer printing and silicon waveguides, providing a solid dispersion foundation for the generation of quantum cascade laser optical frequency combs.

[0009] Furthermore, the quantum cascade laser is a buried structure, which can effectively improve the heat dissipation performance of the laser.

[0010] Furthermore, the active region of the quantum cascade laser is wrapped by a secondary grown semi-insulating layer, which is conducive to injecting carriers into the active region.

[0011] Furthermore, the active region of the quantum cascade laser is a ridge-shaped optical waveguide structure.

[0012] Furthermore, the semi-insulating layer is InP:Fe. InP has a high thermal conductivity and is helpful for heat dissipation of the laser.

[0013] Furthermore, the silicon waveguide includes: a substrate, a silicon waveguide core layer disposed on the substrate, and a passive optical waveguide arranged on the silicon waveguide core layer.

[0014] Furthermore, the III-V epitaxial layer structure of the quantum cascade laser includes, from bottom to top, an N-type indium phosphide substrate, a sacrificial layer, an N-type indium phosphide lower cladding layer, an N-type confinement layer, an active region, a P-type confinement layer, a P-type indium phosphide upper cladding layer and a P-type ohmic contact layer.

[0015] The present invention also provides a method for preparing an on-chip integrated quantum cascade laser optical frequency comb, comprising the following steps:

[0016] S1. Depositing a silicon nitride insulating layer on the surface of the P-type ohmic contact layer of the quantum cascade laser epitaxial wafer;

[0017] S2. Using photolithography and etching to prepare a mask for the active region ridge optical waveguide on the silicon nitride layer, and using dry etching to etch to the N-type indium phosphide lower cladding to form an active region ridge optical waveguide;

[0018] S3. growing a semi-insulating cladding layer on the N-type indium phosphide lower cladding layer, wrapping the horizontal periphery of the active region ridge optical waveguide;

[0019] S4. Forming a semi-insulating cladding layer wrapping the active area by photolithography and dry etching, and etching to the N-type indium phosphide lower cladding;

[0020] S5. Depositing and stripping an N-type indium phosphide lower cladding to prepare an N metal electrode;

[0021] S6. Depositing a silicon nitride insulating protective layer on the surface of the device;

[0022] S7. Spin-coat a DVS-BCB layer on the device surface for planarization;

[0023] S8. dry-etching the DVS-BCB layer, and then dry-etching the SiN insulating layer on the P-type ohmic contact layer until the P-type ohmic contact layer is exposed, and depositing and stripping the P-type metal electrode on the P-type ohmic contact layer;

[0024] S9. Etching back the DVS-BCB layer, and dry etching the N-type indium phosphide lower cladding layer and the sacrificial layer to the N-type indium phosphide substrate;

[0025] S10. Spin-coat the photoresist on the device surface to support the quantum cascade laser;

[0026] S11. Wet drilling of sacrificial layer;

[0027] S12. Transferring quantum cascade lasers to silicon waveguides using micro-transfer printing technology;

[0028] S13. removing the photoresist on the surface of the transferred quantum cascade laser;

[0029] S14. Spin-coat DVS-BCB glue for planarization;

[0030] S15. Etching the DVS-BCB glue until the P metal electrode is exposed, and opening the through hole of the N metal electrode;

[0031] S16. Deposit a metal electrode in the N metal electrode through hole.

[0032] The present invention discloses a method for preparing an on-chip integrated quantum cascade laser optical frequency comb, wherein the quantum cascade laser is micro-transferred onto a silicon waveguide, and the fundamental mode of the waveguide in the active region of the quantum cascade laser is coupled with the fundamental mode of the silicon waveguide to excite an antisymmetric mode, which has the characteristic of small negative dispersion and can realize the regulation of the dispersion in the quantum cascade laser cavity, providing a dispersion basis for the generation of an optical frequency comb. At the same time, the micro-transfer integrated buried quantum cascade laser has good heat dissipation performance. The present invention realizes the efficient integration of quantum cascade lasers on silicon waveguides, and the precise regulation of the dispersion of quantum cascade lasers can be realized through the integration of micro-transfer and silicon waveguides, providing a solid dispersion basis for the generation of quantum cascade laser optical frequency combs, and the micro-transfer quantum cascade laser is a buried structure, which helps to improve the heat dissipation performance.

[0033] Furthermore, the step S12 includes:

[0034] S121. Using a PDMS stamp to stick up a quantum cascade laser, and transferring the quantum cascade laser to a silicon waveguide via the PDMS stamp;

[0035] S122. Spin-coating DVS-BCB glue on the silicon waveguide to adhere the quantum cascade laser to the silicon waveguide, and applying a specific pressure to press the quantum cascade laser to make close contact with the silicon waveguide;

[0036] S123. Apply a specific shear force in the horizontal direction to the PDMS stamp, lift the PDMS stamp in the vertical direction, separate the PDMS stamp and the quantum cascade laser, and complete the transfer of the quantum cascade laser to the silicon waveguide.

[0037] Micro-transfer printing technology is used to extract and transfer the processed quantum cascade lasers to the processed silicon waveguides through the stamp.

[0038] Furthermore, by increasing the number of PDMS stamps, batch transfer integration of quantum cascade laser arrays is achieved.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The on-chip integrated quantum cascade laser optical frequency comb and the preparation method thereof of the present invention realize the efficient integration of quantum cascade laser on silicon waveguide. The precise regulation of quantum cascade laser dispersion can be realized through the integration of micro-transfer printing and silicon waveguide, providing a solid dispersion foundation for the generation of quantum cascade laser optical frequency comb. The buried structure of the micro-transfer quantum cascade laser helps to improve the heat dissipation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the structure of the quantum cascade laser optical frequency comb in Example 1;

[0042] Figure 2 This is a light field simulation diagram of the coupling mode of the quantum cascade laser optical frequency comb in Example 1;

[0043] Figure 3 It is a group velocity dispersion simulation diagram of the coupled mode of the quantum cascade laser optical frequency comb in Example 1;

[0044] Figure 4 It is a schematic diagram of the process of preparing a method for an on-chip integrated quantum cascade laser optical frequency comb in Example 3;

[0045] Figure 5 Schematic diagram of the process of micro-transfer printing technology in Example 3.

[0046] In the accompanying drawings: 1. substrate; 2. silicon waveguide core layer; 3. DVS-BCB layer; 4. N-type indium phosphide lower cladding layer; 5. N-type confinement layer; 6. active region; 7. P-type confinement layer; 8. P-type indium phosphide upper cladding layer; 9. P-type ohmic contact layer; 10. semi-insulating layer; 11. P metal electrode; 12. N metal electrode. DETAILED DESCRIPTION

[0047] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0048] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0049] Embodiment 1

[0050] This embodiment is the first embodiment of an on-chip integrated quantum cascade laser optical frequency comb. Figure 1 As shown, it includes a silicon waveguide and a buried quantum cascade laser integrated on the silicon waveguide by micro-transfer printing technology; wherein the silicon waveguide includes: a sapphire substrate 1, a silicon waveguide core layer 2 arranged on the sapphire substrate 1, and a passive optical waveguide arranged on the silicon waveguide core layer 2; the III-V epitaxial layer structure of the quantum cascade laser includes, from bottom to top, an N-type indium phosphide substrate, a sacrificial layer, an N-type indium phosphide lower cladding layer 4, an N-type confinement layer 5, an active region 6, a P-type confinement layer 7, a P-type indium phosphide upper cladding layer 8, and a P-type ohmic contact layer 9. The micro-transfer printing technology is used to extract the processed quantum cascade laser through a stamp and transfer it to the processed silicon waveguide, and the silicon waveguide and the quantum cascade laser are bonded and solidified through a DVS-BCB layer 3.

[0051] The 6-waveguide fundamental mode of the active region of the quantum cascade laser is coupled with the fundamental mode of the silicon waveguide to excite an antisymmetric mode with a small negative dispersion characteristic to achieve the generation of an optical frequency comb; the antisymmetric mode has a small negative dispersion and can provide efficient dispersion compensation for the generation of an optical frequency comb; the dispersion of the antisymmetric mode is excited by micro-transferring the integrated quantum cascade laser onto the silicon waveguide, thereby providing a dispersion basis for the generation of an optical frequency comb.

[0052] The integrated quantum cascade laser waveguide modes are analyzed by the Lumerical Mode solver. Figure 2 The light field distribution simulation diagram of the antisymmetric mode formed by the coupling of the silicon waveguide fundamental mode and the quantum cascade laser active region 6 optical waveguide fundamental mode shows that most of the light field is concentrated in the quantum cascade laser active region 6, and the quantum cascade laser active region 6 is also the region where photons are generated. The confinement factor of the antisymmetric mode in the active region 6 is close to 98%, so the mode generated by the quantum cascade laser is naturally an antisymmetric mode.

[0053] The group velocity dispersion is numerically simulated by the Lumerical Mode solver. The dispersion simulation results are as follows: Figure 3 As shown. The dotted line represents the dispersion value of the quantum cascade laser when it is not integrated, and the dispersion of its fundamental mode is positive dispersion; the solid line represents the dispersion value of the antisymmetric mode excited by the quantum cascade laser hybrid integrated on the silicon waveguide by micro-transfer, which is a small negative dispersion. Therefore, by micro-transferring to the silicon waveguide, the generation of the quantum cascade laser optical frequency comb is efficiently compensated for dispersion. The hybrid integration of silicon waveguides has expanded more functions and application scenarios.

[0054] The present embodiment is an on-chip integrated quantum cascade laser optical frequency comb, which realizes efficient regulation of the dispersion generated by the optical frequency comb by integrating the quantum cascade laser with the passive platform micro-transfer printing, and the integration with the passive platform can further expand the application scenarios of the quantum cascade laser. The present embodiment realizes the efficient integration of the quantum cascade laser on the silicon waveguide, and the precise regulation of the dispersion of the quantum cascade laser can be achieved through the integration of micro-transfer printing and silicon waveguide, providing a solid dispersion foundation for the generation of the quantum cascade laser optical frequency comb. The micro-transfer quantum cascade laser is a buried structure, which helps to improve the heat dissipation performance.

[0055] Embodiment 2

[0056] This embodiment is a second embodiment of an on-chip integrated quantum cascade laser optical frequency comb, which is similar to the first embodiment, except that the quantum cascade laser active region 6 is a ridge optical waveguide structure and is wrapped by a secondary grown InP:Fe semi-insulating layer 10. The semi-insulating layer 10 is conducive to injecting carriers into the active region 6. InP has a high thermal conductivity, which helps to dissipate heat from the laser.

[0057] Embodiment 3

[0058] This embodiment is the first embodiment of a method for preparing an on-chip integrated quantum cascade laser optical frequency comb. Figure 4 As shown, the following steps are included:

[0059] S1. Depositing a silicon nitride insulating layer on the P-type contact layer of the quantum cascade laser epitaxial wafer, and preparing a mask for the active region 6 optical waveguide in the silicon nitride insulating layer by photolithography and etching;

[0060] S2. By inductively coupled plasma dry etching (ICP-RIE) process, 6 ridge optical waveguides are etched in the active area, and the etching stop layer is the N-type indium phosphide lower cladding layer 4;

[0061] S3. Re-grow a layer of InP:Fe semi-insulating layer 10 around the etched active area 6 ridge optical waveguide from the N-type indium phosphide lower cladding layer 4;

[0062] S4. Photolithography, dry etching excess InP: Fe semi-insulating layer 10, the etch stop layer is N-type indium phosphide lower cladding layer 4;

[0063] S5. Depositing and stripping a specific thickness N metal electrode 12 on the N-type indium phosphide lower cladding layer 4;

[0064] S6. Depositing a silicon nitride insulating protective layer of a specific thickness on the surface of the device;

[0065] S7. Spin-coat a specific thickness of DVS-BCB glue to wrap the entire waveguide structure and flatten it;

[0066] S8. Dry etching DVS-BCB glue, dry etching SiN insulating layer, etching to expose the P-type ohmic contact layer 9, depositing and stripping a specific thickness of the P metal electrode 11;

[0067] S9. Back-etching DVS-BCB glue, dry etching DVS-BCB glue, N-type indium phosphide lower cladding layer 4, sacrificial layer, the etching stop layer is the N-type indium phosphide substrate;

[0068] S10. Spin-coating a photoresist of a specific thickness as a package to support the quantum cascade laser;

[0069] S11. Wet drilling of the sacrificial layer to separate the quantum cascade laser and the substrate 1, and the photoresist protective shell supports the quantum cascade laser;

[0070] S12. The quantum cascade laser is glued by a stamp, aligned and transferred to the processed silicon waveguide. The passive optical waveguide is composed of a sapphire substrate 1, a silicon waveguide core layer 2 disposed on the sapphire substrate 1, and a silicon waveguide arranged on the silicon waveguide core layer 2. A DVS-BCB layer 3 of a specific thickness is spin-coated on the passive optical waveguide to tightly glue the transferred quantum cascade laser;

[0071] S13. Removing the photoresist coating of the transferred quantum cascade laser;

[0072] S14. Spin coating DVS-BCB glue of specific thickness for planarization;

[0073] S15. Dry-etch the DVS-BCB glue until the P metal electrode 11 is exposed, dry-etch the N metal electrode 12 through hole, and dry-etch the silicon nitride insulating layer on the N metal electrode 12 until the N metal electrode 12 is exposed;

[0074] S16. Deposit a metal electrode in the through hole of the N metal electrode 12.

[0075] like Figure 5 As shown, the specific steps of S12 micro-transfer technology include:

[0076] S121. Quantum cascade laser after etching of sacrificial layer with PDMS stamp;

[0077] S122. The stamp that adheres to the quantum cascade laser is lifted, and the tether supporting the photoresist shell is broken;

[0078] S123. Move the stamp that adheres to the quantum cascade laser, transfer it to the silicon waveguide that is spin-coated with DVS-BCB glue, and apply a specific pressure to press the quantum cascade laser. The alignment accuracy is determined by the transfer equipment;

[0079] S124. applying a specific horizontal shear force to the stamp, so that the stamp is separated from the quantum cascade laser;

[0080] S125. Lift the stamp to separate the stamp from the quantum cascade laser.

[0081] In this embodiment, batch transfer integration of quantum cascade laser arrays can also be achieved by increasing the number of PDMS stamps.

[0082] The present invention discloses a method for preparing an on-chip integrated quantum cascade laser optical frequency comb, wherein the quantum cascade laser is micro-transferred onto a silicon waveguide, and the fundamental mode of the waveguide in the active region of the quantum cascade laser is coupled with the fundamental mode of the silicon waveguide to excite an antisymmetric mode, which has the characteristic of small negative dispersion and can realize the regulation of the dispersion in the quantum cascade laser cavity, providing a dispersion basis for the generation of an optical frequency comb. At the same time, the buried quantum cascade laser integrated by micro-transfer has good heat dissipation performance. The present invention realizes the efficient integration of quantum cascade lasers on silicon waveguides, and the precise regulation of the dispersion of quantum cascade lasers can be realized through the integration of micro-transfer and silicon waveguides, providing a solid dispersion basis for the generation of quantum cascade laser optical frequency combs, and the buried structure of the micro-transferred quantum cascade laser helps to improve the heat dissipation performance.

[0083] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0084] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An on-chip integrated quantum cascade laser optical frequency comb, characterized in that: The invention comprises a silicon waveguide and a quantum cascade laser integrated on the silicon waveguide by micro-transfer printing technology; the fundamental mode of the waveguide in the active region (6) of the quantum cascade laser is coupled with the fundamental mode of the silicon waveguide to excite an antisymmetric mode, the antisymmetric mode has the characteristic of small negative dispersion, and can realize the regulation of the dispersion in the quantum cascade laser cavity and the generation of an optical frequency comb.

2. The on-chip integrated quantum cascade laser optical frequency comb according to claim 1, characterized in that: The quantum cascade laser is a buried structure.

3. The on-chip integrated quantum cascade laser optical frequency comb according to claim 2, characterized in that: The quantum cascade laser active region (6) is wrapped by a secondary grown semi-insulating layer (10).

4. The on-chip integrated quantum cascade laser optical frequency comb according to claim 3, characterized in that: The quantum cascade laser active region (6) is a ridge-shaped optical waveguide structure.

5. The on-chip integrated quantum cascade laser optical frequency comb according to claim 3, characterized in that: The semi-insulating layer (10) is InP:Fe.

6. The on-chip integrated quantum cascade laser optical frequency comb according to claim 4, characterized in that: The silicon waveguide comprises: a substrate (1), a silicon waveguide core layer (2) arranged on the substrate (1), and a passive optical waveguide arranged on the silicon waveguide core layer (2).

7. The on-chip integrated quantum cascade laser optical frequency comb according to claim 4, characterized in that: The III-V epitaxial layer structure of the quantum cascade laser comprises, from bottom to top, an N-type indium phosphide substrate, a sacrificial layer, an N-type indium phosphide lower cladding layer (4), an N-type confinement layer (5), an active region (6), a P-type confinement layer (7), a P-type indium phosphide upper cladding layer (8) and a P-type ohmic contact layer (9).

8. A method for preparing an on-chip integrated quantum cascade laser optical frequency comb, characterized in that: The following steps are involved: S1. A silicon nitride insulating layer is deposited on the surface of the P-type ohmic contact layer (9) of the quantum cascade laser epitaxial wafer; S2. Using photolithography and etching to prepare a mask for the active region (6) ridge optical waveguide on the silicon nitride layer, and using dry etching to etch to the N-type indium phosphide lower cladding layer (4) to form an active region (6) ridge optical waveguide; S3. Growing a semi-insulating cladding layer on the N-type indium phosphide lower cladding layer (4) to wrap around the horizontal periphery of the active region (6) ridge optical waveguide; S4. By photolithography and dry etching, a semi-insulating cladding layer (6) is formed to wrap the active area, and the cladding layer (4) is etched to the N-type indium phosphide lower cladding layer; S5. Deposition and stripping of an N-type indium phosphide lower cladding layer (4) to prepare an N metal electrode (12); S6. Depositing a silicon nitride insulating protective layer on the surface of the device; S7. Spin-coating a DVS-BCB layer (3) on the device surface for planarization; S8. dry-etching the DVS-BCB layer (3), and then dry-etching the SiN insulating layer on the P-type ohmic contact layer (9) until the P-type ohmic contact layer (9) is exposed, and depositing and stripping on the P-type ohmic contact layer (9) to prepare a P metal electrode (11); S9. Etching back the DVS-BCB layer (3), and dry etching the N-type indium phosphide lower cladding layer (4), the sacrificial layer to the N-type indium phosphide substrate (1); S10. Spin-coat the photoresist on the device surface to support the quantum cascade laser; S11. Wet drilling of sacrificial layer; S12. Transferring quantum cascade lasers to silicon waveguides using micro-transfer printing technology; S13. removing the photoresist on the surface of the transferred quantum cascade laser; S14. Spin-coat DVS-BCB glue for planarization; S15. Etching the DVS-BCB glue until the P metal electrode (11) is exposed, and opening the through hole of the N metal electrode (12); S16. Depositing a metal electrode in the through hole of the N metal electrode (12).

9. The method for preparing an on-chip integrated quantum cascade laser optical frequency comb according to claim 8, characterized in that: The step S12 comprises: S121. Use PDMS stamp to stick quantum cascade laser; S122. Spin-coating DVS-BCB glue on the silicon waveguide to adhere the quantum cascade laser to the silicon waveguide, and applying a specific pressure to press the quantum cascade laser to make close contact with the silicon waveguide; S123. Apply a specific shear force in the horizontal direction to the PDMS stamp, lift the PDMS stamp in the vertical direction, separate the PDMS stamp and the quantum cascade laser, and complete the transfer of the quantum cascade laser to the silicon waveguide.

10. The method for preparing an on-chip integrated quantum cascade laser optical frequency comb according to claim 9, characterized in that: By increasing the number of PDMS stamps, batch transfer integration of quantum cascade laser arrays is achieved.

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