A brillouin gain assisted on-chip erbium doped laser

Abstract

The application discloses a Brillouin gain assisted on-chip erbium-doped laser, which comprises a micro-ring resonator, a first tapered waveguide, a second tapered waveguide and a spiral waveguide, wherein the micro-ring resonator and the first tapered waveguide are made of an erbium-doped silicon nitride waveguide, and the second tapered waveguide and the spiral waveguide are made of a chalcogenide material; the micro-ring resonator comprises a coupling waveguide which is used for coupling pump light emitted by an erbium-doped laser into the micro-ring resonator, outputting laser signals generated after the pump light is coupled into the micro-ring resonator and sequentially passing through the first tapered waveguide, the second tapered waveguide and the spiral waveguide, and outputting amplified laser signals; and the tip of the first tapered waveguide is coupled and connected with the tip of the second tapered waveguide. The application realizes high-output-power laser signals by using a composite device composed of a cascaded micro-ring resonator of an erbium-doped silicon nitride and a waveguide of a passive chalcogenide material.

Description

Technical Field

[0001] This invention relates to the field of on-chip optoelectronic integrated device technology, and more specifically, to a Brillouin gain-assisted on-chip erbium-doped laser. Background Technology

[0002] On-chip narrow-linewidth lasers (LSLaS) possess advantages such as small size, mature fabrication processes, and flexible controllable output power and wavelength, making them valuable for applications in data communication, biochemical sensing, biomedicine, lidar, and quantum information transmission and applications. Various material systems and implementation methods for generating LLaS have been reported, including laser emission from electrically pumped III-V materials, lasing based on nonlinear optics, and quantum dot lasers based on band engineering. Furthermore, stimulated emission using erbium-doped gain dielectric films is also an important technological path for realizing narrow-linewidth lasers. With advancements in rare-earth ion doping and waveguide etching processes, on-chip erbium-doped lasers have become a focus of research, especially high-performance Brillouin lasers represented by erbium-doped silicon nitride (SiN) films, which have achieved significant progress. Nevertheless, SiN still faces many challenges, including low output power, large linewidth, and low conversion efficiency. To address this issue, researchers proposed a gain-assisted laser implementation scheme, which effectively improves the laser's output power by using a cascaded erbium-doped microring resonator and an erbium-doped helical waveguide structure. However, the helical waveguide in this structure is still an erbium-doped gain medium. In addition to the stimulated emission amplification effect, the erbium-doped gain medium also introduces additional absorption and transmission losses to the laser signal, affecting the overall output performance of the laser signal. Summary of the Invention

[0003] This invention provides a Brillouin gain-assisted on-chip erbium-doped laser, solving the technical problem of low output power caused by the spiral waveguide being the erbium-doped gain medium in existing erbium-doped Brillouin lasers.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: This invention provides a Brillouin gain-assisted on-chip erbium-doped laser, comprising a microring resonator, a first tapered graded waveguide, a second tapered graded waveguide, and a helical waveguide, wherein: The microring resonator and the first tapered waveguide are made of erbium-doped silicon nitride waveguides, and the second tapered waveguide and the spiral waveguide are made of chalcogenide materials; The microring resonator includes a coupling waveguide, which is used to couple the pump light emitted by the erbium-doped laser into the microring resonator, and output the laser signal generated after the pump light is coupled into the microring resonator and then passes through the first tapered waveguide, the second tapered waveguide, and the spiral waveguide in sequence to output the amplified laser signal. The tip of the first tapered waveguide is coupled to the tip of the second tapered waveguide.

[0005] In the aforementioned technical means, one end of the first tapered gradient waveguide is coupled to one end of the coupling waveguide of the micro-ring resonator, the other end of the first tapered gradient waveguide is coupled to one end of the second tapered gradient waveguide, and the other end of the second tapered gradient waveguide is connected to one end of the coupled helical waveguide. The other end of the coupled helical waveguide is used for inputting Brillouin pump light and outputting amplified laser signal. A high-output-power laser signal is achieved by utilizing a composite device composed of a cascaded erbium-doped silicon nitride micro-ring resonator and a passive chalcogenide waveguide. First, the erbium-doped silicon nitride micro-ring resonator generates a laser signal under the action of pump light. Subsequently, the laser signal is amplified by the on-chip high-gain Brillouin gain achieved by the waveguide made of chalcogenide material, thereby obtaining a high-output-power laser signal.

[0006] Furthermore, it also includes a silicon substrate, a silicon dioxide layer, a waveguide device transmission layer, and an upper cladding layer, wherein: The silicon dioxide layer is disposed on the silicon substrate, and the silicon dioxide layer is disposed on the transmission layer of the cascaded waveguide device and the upper cladding layer. The upper cladding layer covers the transmission layer of the cascaded waveguide device, and the micro-ring resonator, the first tapered waveguide, the second tapered waveguide, and the helical waveguide are disposed in the transmission layer of the cascaded waveguide device.

[0007] Furthermore, the radius of the microring resonator is 100~500μm.

[0008] Furthermore, the pump light emitted by the erbium-doped laser is coupled into the microring resonator by directional coupling between the input waveguide and the coupled waveguide.

[0009] Furthermore, the spacing between the first tapered waveguide and the second tapered waveguide is 100~500nm.

[0010] Furthermore, the rotation curve of the helical waveguide can be any one of Bessel bending, Euler bending, or cubic spline bending.

[0011] Furthermore, the chalcogenide material includes any one of As2S3, GeSbS, and GeAsS.

[0012] Furthermore, the thickness of the silicon substrate is 525 μm or 700 μm.

[0013] Furthermore, the thickness of the silicon dioxide layer is 2 to 5 μm.

[0014] Furthermore, the thickness of the upper cladding layer is 1 to 3 μm.

[0015] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: This invention proposes a Brillouin gain-assisted on-chip erbium-doped laser structure. By designing the dimensions of the microring resonator, the pump light at 980 nm or 1480 nm and the C-band laser signal satisfy the microcavity resonance condition. A coupling waveguide couples the pump light to the microring resonator. As the power of the pump light coupled into the microcavity is gradually increased until the gain of the signal light inside the cavity equals the microcavity loss, the laser begins to oscillate. The first and second tapered waveguides couple the laser signal from the erbium-doped silicon nitride into the chalcogenide spiral waveguide. The advantage of this structure is that it utilizes stimulated Brillouin scattering to amplify the weak laser signal of the on-chip erbium-doped laser. By cascading the two functional devices, a Brillouin gain-assisted on-chip erbium-doped laser is realized. This structure increases the freedom of device design, and by adjusting the length of the spiral waveguide and the power of the pump light, it is beneficial to achieve high output power and narrow linewidth laser signals. Attached Figure Description

[0016] Figure 1 A schematic diagram of a Brillouin gain-assisted on-chip erbium-doped laser provided in an embodiment of the present invention; Figure 2 A schematic diagram of the optical mode field distribution of the TE fundamental mode at wavelengths of 1480 nm and 1550 nm provided for an embodiment of the present invention; Figure 3 The transmission spectrum of an erbium-doped silicon nitride microring with a radius of 100 μm and a waveguide width of 1.5 μm provided in the embodiments of the present invention; Figure 4 This is a schematic diagram illustrating the relationship between the coupling coefficient of the microring resonator and the input waveguide and the wavelength, as provided in an embodiment of the present invention. Figure 5 A schematic diagram illustrating the spatial coupling structure relationship between the first tapered waveguide and the second tapered waveguide provided in an embodiment of the present invention; Figure 6 A schematic diagram of mode propagation simulation of the first tapered gradient waveguide and the second tapered gradient waveguide provided for embodiments of the present invention; Figure 7 A schematic diagram of the acoustic mode distribution of a helical waveguide provided in an embodiment of the present invention; In the figure, 1 is a micro-ring resonator, 2 is the first tapered waveguide, 3 is the second tapered waveguide, 4 is a spiral waveguide, 5 is a silicon substrate, 6 is a silicon dioxide layer, 7 is the waveguide device transmission layer, and 8 is the upper cladding. Detailed Implementation

[0017] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent. To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions; It will be understood by those skilled in the art that certain well-known structures and their descriptions may be omitted in the accompanying drawings.

[0018] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Example This invention provides a Brillouin gain-assisted on-chip erbium-doped laser, the specific structure of which is as follows: Figure 1 As shown, it includes a microring resonator 1, a first tapered waveguide 2, a second tapered waveguide 3, and a spiral waveguide 4, wherein: The microring resonator 1 and the first tapered waveguide 2 are made of erbium-doped silicon nitride waveguides, and the second tapered waveguide 3 and the spiral waveguide 4 are made of chalcogenide materials; The microring resonator 1 includes a coupling waveguide, which is used to couple the pump light emitted by the erbium-doped laser into the microring resonator 1, and output the laser signal generated after the pump light is coupled into the microring resonator 1 and then passes through the first tapered waveguide 2, the second tapered waveguide 3 and the spiral waveguide 4 in sequence to output the amplified laser signal. The tip of the first tapered waveguide 2 is coupled to the tip of the second tapered waveguide 3.

[0020] In a specific embodiment, one end of the first tapered gradient waveguide 2 is coupled to one end of the coupling waveguide of the micro-ring resonator, the other end of the first tapered gradient waveguide 2 is coupled to one end of the second tapered gradient waveguide 3, the other end of the second tapered gradient waveguide 3 is connected to one end of the coupled helical waveform waveguide, and the other end of the coupled helical waveguide 4 is used to input Brillouin pump light and output amplified laser signal.

[0021] In this embodiment, stimulated Brillouin scattering (SBS) is proposed to further amplify the laser output signal. Stimulated Brillouin lasers (SBS) are a type of third-order nonlinear optical system with advantages such as GHz-level offset, small gain bandwidth, and high gain. They are currently widely used in microwave photonics, narrow-linewidth Brillouin lasers, stress and temperature detection, etc. To further leverage the advantages of SBS in integrated photonic circuit technology, researchers have proposed various mechanisms for controlling acousto-optic coupling, involving material platforms including silicon nitride, silicon nitride, chalcogenides, and silicon. Chalcogenides, due to their high refractive index, softness, and low sound velocity, can achieve simultaneous confinement of optical and acoustic modes when combined with silicon dioxide. Chalcogenide waveguides can achieve switching gains up to 52 dB, making chalcogenides the preferred material for achieving high-gain on-chip Brillouin gain. In this embodiment, an erbium-doped silicon nitride microring resonator 1 generates a laser signal under pump light. The subsequent laser signal is amplified by stimulated Brillouin scattering, resulting in a high-power laser signal. Specifically: In this invention, the erbium-doped silicon nitride microring resonator 1, under the action of 980 nm or 1480 nm pump light, can excite erbium ions from the ground state to a higher energy level, forming population inversion and generating a C-band stimulated emission optical signal. When the pump light power is further increased so that the gain of the signal light exceeds the cavity loss, laser oscillation will be achieved. This output signal is coupled through a first tapered graded waveguide 2 to a second tapered graded waveguide 3, and then enters a chalcogenide passive spiral waveguide. Under pump light excitation, the laser signal is further enhanced by stimulated Brillouin scattering. This cascaded device utilizes the stimulated emission of erbium ions and the stimulated Brillouin scattering of chalcogenide waveguides, taking advantage of the high erbium ion doping concentration and low loss of silicon nitride material, as well as the softness and low sound velocity of chalcogenide materials, which helps to achieve a high-power laser output signal.

[0022] In a further embodiment, it also includes a silicon substrate 5, a silicon dioxide layer 6, a waveguide device transmission layer 7, and an upper cladding layer 8, wherein: The silicon substrate 5 is provided with the silicon dioxide layer 6, the silicon dioxide layer 6 is provided with the cascaded waveguide device transmission layer 7 and the upper cladding layer 8, the upper cladding layer 8 covers the cascaded waveguide device transmission layer 7, and the micro-ring resonator 1, the first tapered waveguide 2, the second tapered waveguide 3 and the spiral waveguide 4 are disposed in the cascaded waveguide device transmission layer 7.

[0023] In a further embodiment, the radius of the microring resonator 1 is 100~500μm.

[0024] In this embodiment, the cross-sectional structure of the erbium-doped silicon nitride and chalcogenide waveguide is as follows: Figure 2As shown, for the silicon nitride microring, it is necessary to determine the radius of the erbium-doped silicon nitride microring resonator 1 and the coupling distance with the coupled waveguide. To achieve effective laser radiation, both the pump light and the laser signal need to satisfy the microring resonance condition. When the microring radius is 100 μm, the transmission spectrum of the microring is as follows... Figure 3 As shown, both the pump light and the signal light satisfy the resonance condition. By designing the size of the microring resonator, the 980 nm or 1480 nm pump light and the C-band laser signal satisfy the microcavity resonance condition. The pump light is then coupled to the microring resonator 1 using a coupling waveguide. When the power of the pump light coupled into the microcavity is gradually increased until the gain of the signal light inside the cavity equals the microcavity loss, the laser begins to oscillate.

[0025] In a further embodiment, the pump light emitted by the erbium-doped laser is coupled into the microring resonator 1 by directional coupling between the input waveguide and the coupled waveguide.

[0026] The first tapered waveguide 2 and the second tapered waveguide 3 couple the laser signal into the helical waveguide 4. The advantage of this structure is that it utilizes stimulated Brillouin scattering to amplify the weak laser signal from the erbium-doped laser on the chip. By cascading the two functional devices, a Brillouin gain-assisted erbium-doped laser is achieved. This structure increases the freedom of device design; by adjusting the length of the helical waveguide 4 and the power of the pump light, it is beneficial to achieve high output power and narrow linewidth laser signals.

[0027] In a further embodiment, the spacing between the first tapered gradient waveguide 2 and the second tapered gradient waveguide 3 is 100~500nm.

[0028] In this embodiment, to efficiently excite the erbium-doped microring resonator 1 and reduce the laser threshold, it is also necessary to determine the coupling coefficient between the microring resonator 1 and the coupled waveguide. To ensure that the pump light and signal light can be efficiently coupled into the microring resonator 1, this structure adopts a directional coupling structure, such as... Figure 4 The illustration shows the relationship between the microring resonator 1 and the input waveguide, where the spacing is 400 nm, the input straight waveguide width is 1.2 μm, and the coupling region length is 32 μm. The coupling coefficient between the microring and the input waveguide as a function of wavelength was calculated using FDTD simulation software as shown below. Figure 4 As shown in the figure. The simulation results show that the coupling coefficient increases with increasing wavelength, with coupling coefficients of 0.21 and 0.25 corresponding to 1480 nm and 1550 nm, respectively.

[0029] Furthermore, to ensure efficient coupling of the mode field between the microring device and the helical waveguide 4, the dimensions of the first tapered waveguide 2 and the second tapered waveguide 3 also need to be determined. In this embodiment, the spatial coupling relationship between the first tapered waveguide 2 and the second tapered waveguide 3 is as follows: Figure 5 As shown, the mode field transmission form is as follows Figure 6 As shown, the tip width of the first tapered waveguide 2 is 200 nm, the tip width of the second tapered waveguide 3 is 150 nm, the length of the tapered waveguide is 150 μm, the thickness of the intermediate silicon oxide spacer layer is 150 nm, and the calculated transmittance is 99.7%.

[0030] In a specific embodiment, for the waveguide structure described above, the acoustic mode distribution of the chalcogenide helical waveguide 4 is as follows: Figure 7 As shown, the Brillouin frequency shift corresponding to the acoustic mode is approximately 6.708 GHz. Assuming an acoustic quality factor of 400, the corresponding Brillouin gain coefficient is approximately 764 m. -1 W -1 When the output pump light is 200 mW, and the waveguide length and loss are 10 cm and 0.5 dB / cm, respectively, the effective length is approximately 5.9 cm. According to the Brillouin gain calculation formula... It can be seen that the gain obtained by the signal light is approximately 39.12 dB. According to the results, stimulated Brillouin scattering can effectively amplify the laser signal generated by the erbium-doped silicon nitride microring, thereby increasing the output power of the laser.

[0031] In a further embodiment, the rotation curve of the helical waveguide 4 is any one of Bessel bending, Euler bending, or cubic spline bending.

[0032] In a further embodiment, the chalcogenide material includes any one of As2S3, GeSbS, and GeAsS.

[0033] In a further embodiment, the thickness of the silicon substrate 5 is 525 μm or 700 μm.

[0034] In a further embodiment, the thickness of the silicon dioxide layer 6 is 2 to 5 μm.

[0035] In a further embodiment, the thickness of the upper cladding layer 8 is 1 to 3 μm.

[0036] In a further embodiment, the thickness of the waveguide device transmission layer 7 is 600~900nm.

[0037] The same or similar labels correspond to the same or similar parts; The terms used to describe positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A Brillouin gain-assisted on-chip erbium-doped laser, characterized in that, It includes a microring resonator (1), a first tapered waveguide (2), a second tapered waveguide (3), and a helical waveguide (4), wherein: The microring resonator (1) and the first tapered waveguide (2) are made of erbium-doped silicon nitride waveguides, and the second tapered waveguide (3) and the spiral waveguide (4) are made of chalcogenide materials; The microring resonator (1) includes a coupling waveguide, which is used to couple the pump light emitted by the erbium-doped laser into the microring resonator (1), and output the laser signal generated after the pump light is coupled into the microring resonator (1) and passes through the first tapered waveguide (2), the second tapered waveguide (3), and the spiral waveguide (4) in sequence to output the amplified laser signal; The tip of the first tapered waveguide (2) is coupled to the tip of the second tapered waveguide (2).

2. The Brillouin gain-assisted on-chip erbium-doped laser according to claim 1, characterized in that, It also includes a silicon substrate (5), a silicon dioxide layer (6), a waveguide device transmission layer (7), and an upper cladding layer (8), wherein: The silicon dioxide layer (6) is disposed on the silicon substrate (5). The silicon dioxide layer (6) is disposed on the cascaded waveguide device transmission layer (7) and the upper cladding layer (8). The upper cladding layer (8) covers the cascaded waveguide device transmission layer (7). The micro-ring resonator (1), the first tapered waveguide (2), the second tapered waveguide (3) and the spiral waveguide (4) are disposed in the cascaded waveguide device transmission layer (7).

3. The Brillouin gain-assisted on-chip erbium-doped laser according to claim 1, characterized in that, The radius of the microring resonator (1) is 100~500μm.

4. The Brillouin gain-assisted on-chip erbium-doped laser according to claim 1, characterized in that, The pump light emitted by the erbium-doped laser is coupled into the microring resonator (1) by directional coupling between the input waveguide and the coupled waveguide.

5. The Brillouin gain-assisted on-chip erbium-doped laser according to claim 1, characterized in that, The spacing between the first tapered waveguide (2) and the second tapered waveguide (3) is 100~500nm.

6. The Brillouin gain-assisted on-chip erbium-doped laser according to claim 1, characterized in that, The shape of the rotation curve of the helical waveguide (4) is any one of Bessel bending, Euler bending, or cubic spline bending.

7. The Brillouin gain-assisted on-chip erbium-doped laser according to any one of claims 1 to 6, characterized in that, The chalcogenide material includes any one of As2S3, GeSbS, and GeAsS.

8. The Brillouin gain-assisted on-chip erbium-doped laser according to claim 2, characterized in that, The thickness of the silicon substrate (5) is 525 μm or 700 μm.

9. The Brillouin gain-assisted on-chip erbium-doped laser according to claim 2 or 8, characterized in that, The thickness of the silicon dioxide layer (6) is 2 ~ 5 μm.

10. The Brillouin gain-assisted on-chip erbium-doped laser according to claim 9, characterized in that, The thickness of the upper cladding (8) is 1 ~ 3 μm.

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