Diamond on-chip integrated laser and preparation method thereof

Abstract

The invention discloses a diamond on-chip integrated laser and a preparation method thereof, and relates to the technical field of integrated optics, and the on-chip integrated laser comprises a high-power semiconductor laser, a diamond substrate and a waveguide. Wherein the same diamond substrate is divided into a laser integration area and a waveguide integration area; the high-power semiconductor laser is integrated in the laser integration area of the diamond substrate through a thin film circuit; the waveguide is integrated in the waveguide integration area and comprises a waveguide material layer, diamond films are evenly plated on the upper portion and the lower portion of the waveguide material layer and the surfaces of the two sides, in non-laser coupling with the high-power semiconductor laser, of the waveguide material layer, and the end, not plated with the diamond films, of the waveguide material layer is aligned with a light outlet of the high-power semiconductor laser. According to the invention, the luminous efficiency of the integrated optical chip is improved, the thermal crosstalk problem of the chip is solved, and the stable output of the whole laser is ensured.

Description

Technical Field

[0001] The present invention relates to the field of integrated optical technology, and more particularly to an integrated laser on a diamond chip and a preparation method thereof. Background Art

[0002] At present, silicon and silicon dioxide are used as waveguide transmission structures in traditional silicon-based chips. Since silicon is an indirect bandgap material, its luminous efficiency is low and it is not suitable to be used directly as a light source material. In addition, nonlinear effects in silicon (such as two-photon absorption and free carrier absorption effects) will produce additional nonlinear losses when the pump power is high.

[0003] On the other hand, silicon has a large thermo-optical coefficient and is very sensitive to changes in ambient temperature. When a device on the chip generates heat, it will cause a local temperature rise, which in turn affects the performance of adjacent devices through heat conduction. In addition, in silicon photonic chips, different devices are connected to each other through structures such as waveguides and electrodes. These connection structures will also become channels for heat transfer, causing heat to be transferred between devices. In particular, semiconductor lasers are heat-sensitive light sources, and temperature changes greatly affect the performance of the light source.

[0004] Therefore, how to solve the luminous efficiency and thermal crosstalk problems of integrated optical chips needs to be solved urgently. Summary of the invention

[0005] In view of this, the present invention provides a diamond on-chip integrated laser and a method for preparing the same.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention discloses a diamond on-chip integrated laser, comprising:

[0008] High-power semiconductor lasers, diamond substrates and waveguides;

[0009] The diamond substrate is divided into a laser integration area and a waveguide integration area;

[0010] The surface of the laser integration region is provided with a gold-plated layer, and the gold-plated layer is used to make a thin-film circuit for driving the high-power semiconductor laser, and the high-power semiconductor laser is integrated in the laser integration region through the thin-film circuit;

[0011] The waveguide integration region is integrated with a waveguide, and the waveguide includes a waveguide material layer. The upper and lower surfaces of the waveguide material layer and the two side surfaces that are not laser coupled with the high-power semiconductor laser are uniformly coated with a diamond film, and the end of the waveguide material layer that is not coated with the diamond film is aligned with the light outlet of the high-power semiconductor laser.

[0012] Preferably, the high-power semiconductor laser adopts III-V group quaternary compound semiconductor materials, including InGaAsP or AlGaAsP.

[0013] Preferably, the waveguide material layer is made of a waveguide material having a refractive index greater than that of diamond and being transparent at a target wavelength of a high-power semiconductor laser.

[0014] Preferably, the waveguide material includes silicon nitride, lithium niobate, zirconium oxide or tantalum oxide.

[0015] Preferably, the waveguide material layer is doped with erbium ions at a concentration of 1 atomic %.

[0016] Preferably, the overall height of the high-power semiconductor laser is 110 μ m.

[0017] Preferably, the thickness of the diamond substrate is 300-400 μ m.

[0018] Preferably, the surface roughness of the waveguide material layer is less than or equal to 0.4 nm.

[0019] Preferably, the thickness of the waveguide material layer is 50 μ m.

[0020] Another aspect of the present invention also discloses a method for preparing a diamond-on-chip integrated laser, comprising the following steps:

[0021] providing a diamond substrate;

[0022] Dividing a laser integration region and a waveguide integration region on the diamond substrate;

[0023] Forming a gold-plated layer in the laser integration area, and manufacturing a thin-film circuit for driving a high-power semiconductor laser on the gold-plated layer;

[0024] Integrating a high-power semiconductor laser on the thin film circuit;

[0025] preparing a waveguide material layer;

[0026] Using chemical vapor deposition technology, a diamond film is evenly plated on the upper and lower surfaces and both sides of the waveguide material layer to form a waveguide;

[0027] The prepared waveguide is integrated in the waveguide integration region, and the end of the waveguide material layer not coated with the diamond film is aligned with the light outlet of the high-power semiconductor laser.

[0028] Furthermore, the waveguide material layer is prepared by low-pressure chemical vapor deposition.

[0029] Furthermore, the refractive index of the prepared waveguide material layer at a target wavelength of 1550 nm is greater than 2.4.

[0030] Furthermore, the refractive index of the prepared diamond film at a target wavelength of 1550 nm is 2.38.

[0031] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a diamond on-chip integrated laser and a preparation method thereof, which has the following effects:

[0032] The present invention uses diamond as the base material of the integrated laser chip. The high thermal conductivity of diamond can ensure that the heat generated by the high-power semiconductor laser is promptly and efficiently discharged, and the temperature of the laser and the surrounding environment is kept stable, thereby not only improving the working efficiency and stability of the laser, but also enabling the high-power semiconductor laser to be smoothly integrated into the photonic chip, greatly enhancing the overall performance and reliability of the laser integrated photonic chip.

[0033] The present invention structurally integrates a high-power semiconductor laser and a waveguide on the same diamond substrate (i.e., the active and passive parts of the photonic device are integrated on the same diamond base), forming a diamond film-waveguide material-diamond substrate waveguide structure. Since the diamond is in close contact with the surface of the waveguide material, the scattering and energy loss caused by the rough edge of the waveguide material can be solved, while reducing the difficulty of integration.

[0034] The present invention uses a waveguide material doped with erbium ions, which can selectively generate the active gain medium required for lasers, and can generate laser beams by exciting erbium ions to emit light. In addition, since there is no two-photon absorption effect in the waveguide material doped with erbium ions, the waveguide loss is extremely small, which can reach 0.01dB / cm. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0036] Figure 1 A front view of a diamond-on-chip integrated laser provided in an embodiment of the present invention.

[0037] Figure 2 A top view of a diamond-on-chip integrated laser provided in an embodiment of the present invention.

[0038] Figure 3This is a left side view of the diamond-on-chip integrated laser provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Example 1

[0041] Embodiment 1 of the present invention discloses a diamond on-chip integrated laser, which is mainly composed of a high-power semiconductor laser, a diamond substrate and a waveguide, wherein the waveguide is mainly composed of a waveguide material layer and a diamond film, and the diamond substrate 2 and the waveguide are both arranged on the diamond substrate.

[0042] The strong optical signal brought by high-power semiconductor lasers can reduce the accuracy requirements for coupling between photonic devices and ignore the losses caused by some structures, thereby improving the performance of photonic chips. The powerful heat dissipation capacity of the diamond substrate can quickly and effectively diffuse the high heat generated by high-power semiconductor lasers into the environment, reducing the impact of heat on laser performance. Because diamond is close to the silicon nitride surface, it can solve the scattering and energy loss caused by the rough edge of silicon nitride, and integration can be carried out with slightly lower process accuracy.

[0043] Combine the following Figure 1 , Figure 2 , Figure 3 , the structure of the integrated laser on the diamond sheet of the present invention is further explained.

[0044] High-power semiconductor laser 1: Using III-V group quaternary compound semiconductor materials, such as InGaAsP / AlGaAsP and other materials, the overall height of high-power semiconductor laser 1 is 110 μ m, can generate over 100mW power, such as Figure 1 , Figure 2 As shown, in the embodiment of the present invention, the high-power semiconductor laser 1 adopts a ridge waveguide structure with a protrusion in the middle of the upper surface.

[0045] Diamond substrate 2: a substrate made of diamond material with a thickness of 300 μ m-400 μ m, preferably 300 μm; A high-power semiconductor laser 1 is integrated on a diamond substrate 2. Specifically, a gold-plated layer 3 is provided on the surface of the integrated region of the high-power semiconductor laser on the diamond substrate 2 to produce a thin-film circuit for driving the high-power semiconductor laser 1. The high-power semiconductor laser 1 is connected to the thin-film circuit on the gold-plated layer 3.

[0046] The thermal conductivity of diamond can usually reach 2000-2600W / (m·K), which is one of the materials with the highest thermal conductivity in nature. Using diamond as a substrate can utilize its excellent thermal conductivity to quickly disperse the heat generated by the components inside the chip and export it to the external environment, thereby significantly reducing the chip temperature in a very short time, effectively alleviating or even eliminating the thermal crosstalk phenomenon. The gold-plated layer 3 is carefully set in the laser integration area on the diamond substrate to achieve precise division of functional areas. Given the excellent electrical conductivity of gold, these specific areas are carefully designed to carry the circuit connection of high-power semiconductor lasers, ensuring efficient and stable current transmission, thereby optimizing the performance and efficiency of the laser. Such a design not only demonstrates the exquisite integration of material science, but also greatly improves the overall operating efficiency of the laser system.

[0047] Waveguide corresponding to the high-power semiconductor laser: The waveguide is located on one side of the high-power semiconductor laser 1 on the diamond substrate 2, and includes a waveguide material layer 4 and a diamond film 5 on the surface. Specifically, the upper and lower parts of the waveguide material layer 4 and the two sides that are not laser coupled with the high-power semiconductor laser 1 are uniformly coated with diamond film 5.

[0048] In a specific embodiment, Figure 1 As shown, the thickness of the diamond film on the lower surface of the waveguide material layer 4 is about 500nm, and the thickness of the diamond film on the upper surface and both sides is about 300nm; the thickness of the waveguide material layer 4 itself is about 50 μ m, with a diamond film on the lower surface, so that the waveguide material layer 4 is coupled and aligned with the light output port of the high-power semiconductor laser 1.

[0049] exist Figure 1-2 In the illustrated embodiment, the lower surface of the waveguide material layer 4 is also provided with a diamond film 5, and the waveguide material layer 4 is integrated on the diamond substrate through the diamond film 5; in other embodiments, the diamond film on the lower surface of the waveguide material layer can also be prepared integrally with the diamond substrate, that is, the waveguide area on the diamond substrate is prepared with a raised platform of a certain height, the waveguide material layer 4 is directly prepared on the raised platform, and a uniform diamond film is plated on the upper surface and both sides of the waveguide material layer.

[0050] The waveguide material layer uses a waveguide material with a refractive index greater than that of diamond and transparent at the target wavelength of the high-power semiconductor laser, specifically including silicon nitride, lithium niobate, zirconium oxide, tantalum oxide, etc.

[0051] Specifically, the silicon nitride waveguide layer has a high refractive index (greater than 2.4) near the target wavelength of 1550 nm for high-power semiconductor lasers, while the refractive index of the diamond film is 2.38.

[0052] The present invention constructs a waveguide structure of diamond film-waveguide-diamond film, and the waveguide has low loss characteristics and excellent heat dissipation performance.

[0053] It is worth noting that although Figure 1-3 The waveguide shown is a straight waveguide structure, but in actual production, by introducing advanced process steps such as photolithography, various complex waveguide structures can be flexibly designed and prepared, including but not limited to curved waveguides, beam splitters, couplers, etc., to meet the specific needs of different application scenarios.

[0054] In addition, in traditional silicon-based chips, silicon and silicon dioxide are used as waveguide transmission structures. Since silicon is an indirect bandgap material, its luminous efficiency is low and it is not suitable to be used directly as a light source material. In addition, nonlinear effects in silicon (such as two-photon absorption and free carrier absorption effects) will produce additional nonlinear losses when the pump power is large.

[0055] Therefore, in another improved embodiment of the present invention, a waveguide material doped with erbium ions is used. After being doped with erbium ions, the waveguide material can selectively produce the active gain medium required for the laser; by exciting the erbium ions, it is enabled to emit light and generate a laser beam, and because waveguide materials such as silicon nitride, lithium niobate, zirconium oxide, and tantalum oxide doped with erbium ions have no two-photon absorption effect, the waveguide loss is extremely small, which can reach 0.01 dB / cm, and its transparent band includes 0.4μm to 2.35μm.

[0056] In a more specific embodiment, the concentration of erbium ions doped in the waveguide material may be set to 1 atomic percent.

[0057] Example 2

[0058] Embodiment 2 discloses a method for preparing the integrated laser described in Embodiment 1, comprising the following steps:

[0059] providing a diamond substrate;

[0060] Dividing a laser integration region and a waveguide integration region on the diamond substrate;

[0061] Gold is plated on the laser integration area to form a gold-plated layer, and a thin-film circuit for driving a high-power semiconductor laser is fabricated on the gold-plated layer;

[0062] Integrating a high-power semiconductor laser on the thin film circuit;

[0063] preparing a waveguide material layer;

[0064] Using chemical vapor deposition technology, a diamond film is evenly plated on the upper and lower surfaces and both sides of the waveguide material layer to form a waveguide;

[0065] The prepared waveguide is integrated in the waveguide integration region, and the end of the waveguide material layer not coated with the diamond film is aligned with the light outlet of the high-power semiconductor laser.

[0066] The overall height of the waveguide prepared in the above method is about 50 μ m, specially designed to align with the laser light outlet. By adjusting the gas flow rate, waveguide materials with different refractive indices can be customized to meet diverse optical needs.

[0067] The diamond film is prepared by chemical vapor deposition (CVD) technology. Specifically, a diamond film with a thickness between 300 and 500 nm is uniformly coated on the upper and lower surfaces of the waveguide material and on both sides of the non-laser coupling. Specifically, the thickness of the diamond film on the lower surface is about 500 nm, and the thickness of the diamond film on the upper surface and both sides is about 300 nm.

[0068] The waveguide material in the present invention is prepared by low-pressure chemical vapor deposition (LPCVD), which can not only accurately control the thickness of the waveguide material at the nanometer level, but also ensure that its surface roughness is less than 0.4nm, greatly reducing the scattering loss between the upper and lower cladding and core layer interfaces in the waveguide structure.

[0069] Comparative example:

[0070] The diamond on-chip integrated laser provided by the present invention is compared with the current silicon-based photonic integrated chip.

[0071] Test method:

[0072] The main performance indicators of the two devices, including waveguide loss, thermal conductivity and dispersion, were tested using standard test methods. Specifically, the high-power laser part was powered by an external source meter, and a detector was connected to the light output point of the silicon nitride waveguide to compare the saturation power and wavelength differences between it and the silicon-based photonic chip under the same current. These parameters reflect its thermal conductivity.

[0073] The test results show that under the same test conditions, the integrated photonic chip on a diamond sheet provided by the present invention has lower loss and, at a larger input current, the laser is less affected by thermal crosstalk and has a higher degree of integration.

[0074] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0075] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A diamond on-chip integrated laser, characterized in that: include: High-power semiconductor lasers, diamond substrates and waveguides; The diamond substrate is divided into a laser integration area and a waveguide integration area; The surface of the laser integration region is provided with a gold-plated layer, and the gold-plated layer is used to make a thin-film circuit for driving the high-power semiconductor laser, and the high-power semiconductor laser is integrated in the laser integration region through the thin-film circuit; The waveguide integration region is integrated with a waveguide, and the waveguide includes a waveguide material layer. The upper and lower surfaces of the waveguide material layer and the two side surfaces that are not laser coupled with the high-power semiconductor laser are uniformly coated with a diamond film, and the end of the waveguide material layer that is not coated with the diamond film is aligned with the light outlet of the high-power semiconductor laser.

2. The diamond-on-chip integrated laser according to claim 1, characterized in that: The high-power semiconductor laser adopts III-V group quaternary compound semiconductor materials, including InGaAsP or AlGaAsP.

3. The diamond-on-chip integrated laser according to claim 1, characterized in that: The waveguide material layer is made of a waveguide material having a refractive index greater than that of diamond and being transparent at a target wavelength of a high-power semiconductor laser.

4. The diamond-on-chip integrated laser according to claim 3, characterized in that: The waveguide material includes silicon nitride, lithium niobate, zirconium oxide or tantalum oxide.

5. The diamond-on-chip integrated laser according to claim 1, characterized in that: The waveguide material layer is doped with erbium ions at a concentration of 1 atomic percent.

6. The diamond on-chip integrated laser according to claim 1, characterized in that: The thickness of the diamond substrate is 300 μ m-400 μ m.

7. A method for preparing a diamond-on-chip integrated laser, characterized in that: The following steps are involved: providing a diamond substrate; Dividing a laser integration region and a waveguide integration region on the diamond substrate; Forming a gold-plated layer in the laser integration area, and manufacturing a thin-film circuit for driving a high-power semiconductor laser on the gold-plated layer; Integrating a high-power semiconductor laser on the thin film circuit; preparing a waveguide material layer; Using chemical vapor deposition technology, a diamond film is evenly plated on the upper and lower surfaces and both sides of the waveguide material layer to form a waveguide; The prepared waveguide is integrated in the waveguide integration region, and the end of the waveguide material layer not coated with the diamond film is aligned with the light outlet of the high-power semiconductor laser.

8. The method for preparing a diamond-on-chip integrated laser according to claim 7, characterized in that: The waveguide material layer is prepared by low-pressure chemical vapor deposition.

9. The method for preparing a diamond-on-chip integrated laser according to claim 7, characterized in that: The refractive index of the prepared waveguide material layer at a target wavelength of 1550 nm is greater than 2.

4.

10. The method for preparing a diamond-on-chip integrated laser according to claim 7, characterized in that: The refractive index of the prepared diamond film at the target wavelength of 1550 nm is 2.38.

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