A multi-band laser

Abstract

The application discloses a multi-waveband laser, comprising: a gain module, comprising at least two gain media, the at least two gain media corresponding to at least two working wavebands one by one, the gain media being used for amplifying propagating light of the corresponding working waveband propagating to the gain media; a filter module, comprising at least two filter components, the at least two filter components being connected to the at least two gain media one by one, the filter component being used for selecting frequency of the propagating light propagating through the corresponding gain medium; and a converging part, connected to the at least two filter components respectively, used for forming output light by the propagating light propagating through the at least two filter components. The application can realize multi-waveband output, and can respectively establish independent frequency selection conditions, feedback conditions and tuning conditions for each working waveband, and can optimize filter parameters and feedback parameters according to the working wavelength of each working waveband, thereby improving the consistency and stability of the output performance of each working waveband.

Description

Technical Field

[0001] This invention relates to the field of optical systems, and in particular to a multi-band laser. Background Technology

[0002] Integrated tunable lasers are core light source devices in wavelength division multiplexing (WDM) coherent optical communication systems. As high-speed coherent optical communication systems evolve towards 800G, 1.6T, and even higher speeds, lasers are required not only to have extremely narrow linewidths but also to have a frequency tuning range covering multiple traditional communication bands such as O, S, C, and L, to meet the demands of ultra-high capacity transmission and flexible wavelength resource configuration. However, traditional external cavity tunable lasers are typically limited by the gain bandwidth of a single gain chip, making it difficult to achieve ultra-wideband continuous coverage across multiple communication bands.

[0003] To extend the operating wavelength of lasers, existing solutions propose using multiple gain media to share an external cavity filter tuning component, achieving multi-band output by switching between different gain media. However, since different bands share the same filter tuning component, it is difficult to establish optimal frequency selection and feedback conditions for each band separately. The filtering characteristics, coupling characteristics, and propagation loss of the filter tuning component are closely related to the operating wavelength and are affected by factors such as the size of the resonant structure, waveguide parameters, and coupling structure. With fixed structural parameters, it is difficult to simultaneously satisfy the optimal operating conditions for multiple bands such as O, S, C, and L. This may result in differences in the feedback intensity obtained in different bands, leading to problems such as unbalanced output power, degraded linewidth performance, inconsistent tuning efficiency, and decreased system stability. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-band laser that can achieve multi-band output and can independently optimize filtering and feedback for each band, thereby improving the consistency and stability of the output performance of each band.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A multi-band laser, comprising:

[0007] A gain module includes at least two gain media, each of which corresponds to at least two operating wavelengths. The gain media are used to amplify the propagating light of the corresponding operating wavelength to which the light propagates.

[0008] A filtering module includes at least two filtering components, which are connected one-to-one with the at least two gain media. The filtering components are used to select the frequency of the propagating light that propagates through the corresponding gain media.

[0009] The confluence section is connected to the at least two filter components respectively, and is used to form output light from the propagating light that has passed through the at least two filter components.

[0010] Optionally, the filtering component includes at least two microrings arranged sequentially, such that the propagating light passing through the at least two microrings is superimposed to form the frequency-selected propagating light, wherein the at least two microrings have different free spectral ranges.

[0011] Optionally, the filtering component includes an input waveguide, a first to Mth micro-rings, and a first to M-1th bent waveguide, where M is a positive integer greater than or equal to 2;

[0012] The input waveguide, the first to the Mth microrings and the first to the (M-1)th bent waveguides are arranged side by side, the first to the Mth microrings are arranged sequentially, the mth bent waveguide is arranged between the mth microring and the (m+1)th microring, m∈[1, M-1], the input waveguide is arranged on one side of the first microring, and the input waveguide is connected to the gain medium corresponding to the filter component.

[0013] Optionally, the filtering component further includes an output waveguide;

[0014] The confluence section includes a main waveguide, and the output waveguides of the at least two filter components are connected in series through the main waveguide.

[0015] Optionally, the gain medium is also used to generate laser light corresponding to the operating wavelength, so that the laser light is optically amplified to form the propagating light corresponding to the operating wavelength.

[0016] Optionally, it also includes:

[0017] A reflecting part, connected to the converging part, is used to reflect at least part of the propagating light of any working band emitted from the converging part, so that the propagating light of any working band oscillates.

[0018] The gain medium is also used to reflect the propagating light that has propagated to the gain medium, causing the propagating light to oscillate.

[0019] Optionally, the reflectivity of the reflective portion for the propagating light in the at least two operating wavelengths can be adjusted.

[0020] Optionally, it also includes:

[0021] A reflecting part, connected to the converging part, is used to reflect at least part of the propagating light of any working band emitted from the converging part, so that the propagating light of any working band oscillates.

[0022] The reflective part includes:

[0023] The first transmission arm is used to transmit the first split beam of the propagating light and to transmit the first return beam to the confluence.

[0024] The second transmission arm is used to transmit the second split beam of the propagating light and to transmit the second return light.

[0025] A coupler, connected to the first transmission arm and the second transmission arm respectively, is used to transmit the first split beam and the second split beam into the ring waveguide, and to merge the first split beam and the second split beam transmitted back from the ring waveguide, and to split the merged beam into the first return beam and the second return beam, the first return beam being transmitted into the first transmission arm and the second return beam being transmitted into the second transmission arm.

[0026] The ring waveguide, connected to the coupler, is used to enable the first split beam and the second split beam to propagate in opposite directions along the ring waveguide.

[0027] Optionally, the first transmission arm is further configured to change the optical path of the first split beam, and the second transmission arm is further configured to change the optical path of the second split beam, so as to change the optical path difference between the first split beam and the second split beam, making the reflectivity of the reflective part for the propagation light of the at least two working wavelengths adjustable.

[0028] Optionally, it also includes an output terminal connected to the reflector for outputting light.

[0029] As can be seen from the above technical solution, the multi-band laser provided by the present invention can realize multi-band output, and set independent gain medium and filtering components for different working bands, so that independent frequency selection conditions, feedback conditions and tuning conditions can be established for each working band. The filtering parameters and feedback parameters of each working band can be optimized according to its own working wavelength, which can improve the consistency and stability of the output performance of each working band. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A schematic diagram of a multi-band laser provided in one embodiment;

[0032] Figure 2A schematic diagram of a multi-band laser is provided for yet another embodiment;

[0033] Figure 3 This is a schematic diagram of the coupling between the microring and the waveguide of the filter component of a multi-band laser according to an embodiment;

[0034] Figure 4 Simulation results show the coupling transmittance of the microring of the filter component as a function of the coupling gap at different operating wavelengths.

[0035] The reference numerals in the accompanying drawings include:

[0036] 100 - Gain module, 101 - First gain medium, 102 - Second gain medium, 103 - Third gain medium, 104 - Fourth gain medium, 10N - Nth gain medium;

[0037] 200 - Filtering module, 201 - First filtering component, 202 - Second filtering component, 203 - Third filtering component, 204 - Fourth filtering component, 20N - Nth filtering component, 2041 - Input waveguide, 2042 - First micro-ring, 2043 - First bent waveguide, 2044 - Second micro-ring;

[0038] 300 - Convergence section, 301 - Main waveguide, 400 - Reflector section, 401 - First transmission arm, 402 - Second transmission arm, 403 - Ring waveguide, 500 - Output end. Detailed Implementation

[0039] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0040] For reference Figure 1 , Figure 1 A schematic diagram of a multi-band laser is provided as an embodiment, such as... Figure 1 As shown, the multi-band laser provided in this embodiment includes:

[0041] The gain module 100 includes at least two gain media, each of which corresponds to at least two operating wavelengths. The gain media are used to amplify the propagating light of the corresponding operating wavelength that propagates to the gain media.

[0042] The filtering module 200 includes at least two filtering components, which are connected one-to-one with the at least two gain media. The filtering components are used to select the frequency of the propagating light that propagates through the corresponding gain media.

[0043] The confluence section 300 is connected to the at least two filter components respectively, and is used to form output light from the propagating light that has passed through the at least two filter components.

[0044] Gain media amplify propagating light, meaning that the gain medium increases the power of the propagating light. Filtering components enable frequency selection of propagating light, meaning that after the propagating light passes through the filtering component, the frequency of the propagating light emitted by the filter component is the desired frequency.

[0045] For any one of the at least two gain media, the gain media is used to amplify the propagating light corresponding to the operating band of the gain media. For any one of the at least two filter components, the filter component is used to select the frequency of the propagating light corresponding to the operating band of the filter component.

[0046] The propagating light of any one of the at least two operating bands propagates through the corresponding gain medium and the corresponding filter component, forming an oscillation and generating the output light of the operating band.

[0047] For example, the gain module 100 includes a first gain medium 101, a second gain medium 102, a third gain medium 103, a fourth gain medium 104 to an Nth gain medium 10N, and the filter module 200 includes a first filter component 201, a second filter component 202, a third filter component 203, a fourth filter component 204 to an Nth filter component 20N, where N is a positive integer greater than or equal to 2. At least two operating bands are included: a first operating band [λ]. 11 , λ 12 ], second working band [λ 21 , λ 22 The third working band [λ] 31 , λ 32 ], fourth working band [λ 41 , λ 42 ], ..., the Nth working band is [λ N1 , λ N2 ].

[0048] This embodiment of the multi-band laser can achieve multi-band output, and separate gain media and filtering components are set for different working bands. This allows for the establishment of independent frequency selection conditions, feedback conditions and tuning conditions for each working band. The filtering parameters and feedback parameters for each working band can be optimized according to its own working wavelength, which can improve the consistency and stability of the output performance of each working band.

[0049] This multi-band laser can operate in both single-band and multi-band modes. In single-band mode, the gain medium and filter components for the corresponding operating band can be selected according to the required wavelength of the output light. In multi-band mode, multiple gain media and corresponding filter components can be selected to operate simultaneously, allowing output light from multiple operating bands to be emitted from the laser at the same time, achieving multi-band parallel output. This can be used for wavelength multiplexing output or other multi-carrier light source applications.

[0050] In some embodiments, the filtering component includes at least two microrings arranged sequentially, such that propagating light passing through the at least two microrings is superimposed to form frequency-selective propagating light, wherein the at least two microrings have different free spectral ranges. A microring is a closed-loop waveguide. When propagating light of the corresponding operating wavelength propagates in the bus waveguide and passes through the coupling region of the microring, a portion of the optical field energy enters the microring through the evanescent wave effect. The light entering the microring undergoes a phase change with each propagation revolution, the amount of which is related to the microring's circumference and the material's refractive index. When the wavelength of the light satisfies the condition that the microring's circumference is an integer multiple of its wavelength (i.e., the phase-matching condition), the light propagates back to the coupling region and interferes with newly entering light from the coupling region. When the phase difference between the two is an integer multiple of 2π, constructive interference occurs, causing the energy of that wavelength to continuously accumulate and strengthen within the microring. Light of that wavelength can be selectively output, while other wavelengths that do not meet this condition interfere destructively due to phase mismatch.

[0051] The free spectral range refers to the interval between two adjacent resonant wavelengths (or resonant frequencies) in the transmission spectrum of a microring. The free spectral range is related to the perimeter of the microring and the refractive index of the material. The filter assembly comprises at least two microrings forming a microring vernier structure.

[0052] In some embodiments, the filtering component includes an input waveguide, first to Mth microrings, and first to M-1th bent waveguides, where M is a positive integer greater than or equal to 2. The input waveguide, first to Mth microrings, and first to M-1th bent waveguides are arranged side by side, with the first to Mth microrings arranged sequentially. The mth bent waveguide is arranged between the mth and m+1th microrings, where m ∈ [1, M-1]. The input waveguide is arranged on one side of the first microring, and the input waveguide is connected to the gain medium corresponding to the filtering component. There is a gap between the input waveguide and the first microring. One end of the mth bent waveguide is adjacent to the mth microring with a gap between them, and the other end of the mth bent waveguide is adjacent to the m+1th microring with a gap between them. The bent waveguide can be a U-shaped waveguide or an inverted U-shaped waveguide. For example, refer to... Figure 2 , Figure 2 A schematic diagram of a multi-band laser is provided for yet another embodiment, as shown below. Figure 2As shown, taking the fourth filter component 204 as an example, the fourth filter component 204 includes an input waveguide 2041, a first micro-ring 2042, a first bent waveguide 2043, and a second micro-ring 2044 arranged side by side. The input waveguide 2041 is connected to the fourth gain medium 104. The input waveguide 2041 and the first micro-ring 2042 are arranged adjacent to each other with a gap between them. One end of the first bent waveguide 2043 is arranged adjacent to the first micro-ring 2042 with a gap between them, and the other end of the first bent waveguide 2043 is arranged adjacent to the second micro-ring 2044 with a gap between them. Figure 2 The diagram illustrates a filter component consisting of two microrings. By using two microrings with different free spectral ranges to generate a vernier effect, a wide range of wavelength selection and single longitudinal mode output can be achieved.

[0053] At least two filter components can be designed with separate free spectral ranges, microring radii, waveguide widths, and coupling gaps for each microring, ensuring optimal filtering and feedback performance across all operating bands. The coupling gap refers to the distance between the microring's annular waveguide and its adjacent straight waveguide (bus waveguide), and can be either an air gap or the thickness of the filling medium.

[0054] In a specific example, taking a single microring coupling unit in a silicon nitride platform dual-microring filter as an example, while maintaining the waveguide structure and microring dimensions, the coupling gap and operating wavelength are varied to simulate and analyze the coupling transmittance of the microring at different wavelengths. The waveguide and the ring waveguide serving as the microring in the silicon nitride platform dual-microring filter are made of silicon nitride. (See reference...) Figure 3 , Figure 3 This is a schematic diagram of the coupling between the microring and the waveguide in the filtering component of a multi-band laser according to one embodiment. Figure 3 For illustration only Figure 4 The definition of the coupling region and coupling transmittance κ² between a single microring and a straight waveguide in the simulation does not indicate that the filtering component of this application contains only one microring; the filtering component in the embodiments of this application can still be composed of a dual-microring or multi-level cascaded microring structure. (See reference...) Figure 4 , Figure 4Simulation results of the coupling transmittance κ² as a function of the coupling gap Gap at different operating wavelengths are presented. It can be seen that, under the same coupling gap condition, there are significant differences in the coupling transmittance corresponding to different operating wavelengths. For example, when the coupling gap is 0.70 μm, the coupling transmittances at 1310 nm, 1495 nm, 1550 nm, and 1595 nm are 0.0316, 0.1588, 0.2288, and 0.3003, respectively, with the coupling transmittance at 1595 nm being approximately 9.5 times that of the 1310 nm band. Since the coupling transmittance determines the proportion of optical power entering the external cavity filter and feedback loop, if the existing common second-stage filter is used, different wavelengths will obtain significantly different feedback optical power, making it difficult to maintain consistent external cavity feedback conditions across different wavelengths. This, in turn, affects the laser's oscillation threshold, output power, side-mode suppression ratio (SMSR), linewidth, and tuning stability, making it difficult to achieve consistent performance optimization across wavelengths. In contrast, this embodiment configures independent filtering components for different operating bands, and can optimize the micro-ring radius and coupling gap according to each band, so that different bands can obtain similar coupling transmittance and feedback strength.

[0055] Furthermore, the coupling transmittance of the microring simultaneously affects the filter's passband loss, resonant peak linewidth, intracavity photon lifetime, and effective feedback intensity to the gain medium. When the coupling transmittance is too low, insufficient external cavity feedback may lead to an increase in the oscillation threshold, a decrease in output power, or a weakening of the linewidth narrowing effect. When the coupling transmittance is too high, the filter selectivity decreases, the resonant peak broadens, or side modes receive excessive feedback, which may reduce the side-mode rejection ratio and affect single-mode stability. Therefore, for external cavity lasers operating across multiple bands such as O, S, C, and L, it is difficult to simultaneously meet the optimal coupling conditions for different bands using only the same common microring filter. This application addresses this by setting independent filter components for different bands, allowing each band to independently determine the microring size, coupling gap, and coupling transmittance. Combined with a broadband tunable reflectivity feedback structure, the effective feedback ratio can be adjusted, thereby achieving low-loss feedback, high SMSR, narrow linewidth, and stable tuning across different bands.

[0056] It should be noted that, Figure 3 and Figure 4 This paper uses a single microring coupling unit in a silicon nitride platform as an example to illustrate the coupling transmittance simulation. The specific coupling transmittance values ​​may vary depending on the material platform, waveguide cross-section, bending radius, or coupler type. However, the variation of the microring coupling transmittance with operating wavelength, coupling gap, and waveguide mode distribution is consistent. This application is not limited to... Figure 3 and Figure 4 The specific structural parameters and simulation values ​​are shown.

[0057] exist Figure 2 The illustration uses a filter component comprising two microrings as an example. In practical applications, the filter component can include one or more of the following: two microrings, three microrings, four microrings, or more levels of microrings, which can further improve filtering performance and mode selection capability. Two microrings form a two-microring vernier structure, three microrings form a three-microring vernier structure, four microrings form a four-microring vernier structure, and more levels of microrings form a cascaded structure.

[0058] In some embodiments, the filtering component further includes an output waveguide disposed on one side of the Mth microring and connected to the confluence portion 300. The output waveguide is disposed adjacent to the Mth microring and spaced apart from it.

[0059] In some embodiments, the merging section 300 includes a main waveguide 301, through which the output waveguides of the at least two filtering components are connected in series. The output waveguides of the at least two filtering components are connected in series, and the propagating light transmitted from any of the filtering components is transmitted through the main waveguide 301. Propagating light from different operating wavelengths transmitted from the at least two filtering components can merge in the main waveguide 301. The main waveguide 301 may be referred to as a bus waveguide. In some embodiments, the merging section 300 may further include an arrayed waveguide grating (AWG), a star coupler, a multimode interference coupler, or a Y-branched waveguide.

[0060] In some embodiments, the filtering component may also employ at least one or a combination of at least two of the following: Fabry-Perot cavity, Bragg grating, Mach-Zehnder interferometer (MZI), asymmetric Mach-Zehnder interferometer (AMZI), and comb mirror. As long as it can form independent frequency selection and feedback functions for different operating bands, it is also within the protection scope of this invention.

[0061] At least two filter components can use filter components with the same structure, or they can use filter components with different structures according to different operating bands. As long as independent frequency selection, independent tuning and independent filtering control can be achieved for each different operating band, they are all within the protection scope of this invention.

[0062] In some embodiments, the gain medium is also used to generate the received laser light corresponding to the operating wavelength, which is then amplified to form propagating light of the corresponding operating wavelength. The gain medium can generate the received laser light corresponding to the operating wavelength by electrical drive. This embodiment avoids the need for pump light to be input into the gain medium in multi-band lasers, thus reducing the structural complexity of the laser.

[0063] In some embodiments, the gain medium is also used to reflect the propagating light that has reached the gain medium, causing the propagating light to oscillate. In this embodiment, the gain medium forms one cavity surface of the resonant cavity of the multi-band laser, avoiding the need for a separate cavity surface in the laser and helping to reduce the structural complexity of the multi-band laser. In some embodiments, the gain medium has a first end face and a second end face. The first end face is a reflective surface, and the second end face is a transmission surface. The propagating light from the filter component enters the gain medium through the transmission surface. The gain medium amplifies the propagating light. After being reflected by the reflective surface, the propagating light passes through the transmission surface and is transmitted out of the gain medium to further propagate to the filter component.

[0064] The gain medium may be, but is not limited to, a reflective semiconductor optical amplifier (RSOA), a semiconductor optical amplifier (SOA), a distributed feedback (DFB) laser, a Fabry-Perot laser, or other active devices capable of providing optical gain.

[0065] In some embodiments, the multi-band laser further includes a reflector 400 connected to a collector 300, used to at least partially reflect the propagating light of any operating band emitted from the collector 300, causing the propagating light of any operating band to oscillate. In this embodiment, the reflector 400 forms one cavity surface of the resonant cavity of the multi-band laser, and the gain medium is also used to reflect the propagating light propagating to the gain medium, which can form another cavity surface of the resonant cavity of the multi-band laser.

[0066] In some embodiments, the reflectivity of the reflector 400 is adjustable for propagating light in at least two operating bands. The reflector 400 can be a broadband tunable reflectivity feedback structure, capable of dynamically adjusting the external cavity feedback intensity according to the current operating band, achieving feedback compensation, power equalization, and linewidth optimization between different operating bands. Compared to existing fixed reflectivity feedback structures, this scheme can compensate for performance differences between gain media, filters, and feedback paths in different bands, achieving cross-band power equalization, feedback optimization, and stable single-mode output. The reflector 400 uses an adjustable reflectivity structure instead of a fixed reflectivity structure, dynamically adjusting the feedback ratio according to the gain level of the gain media, filter component loss, and external cavity loss in different operating bands, achieving feedback compensation and power equalization between different operating bands, improving cross-band output consistency, and enhancing the laser's stability, side-mode rejection ratio, and linewidth performance. In addition, this multi-band laser is equipped with independent filtering components for different operating bands. The micro-ring radius and coupling gap can be optimized according to each band to achieve similar coupling transmittance and feedback intensity for different bands. At the same time, the adjustable reflector 400 further compensates for the feedback differences of different operating bands, so that each operating band in the broadband tuning range can obtain relatively consistent feedback conditions, thereby improving the consistency of output power, side-mode rejection ratio, linewidth and tuning stability.

[0067] The 300-unit converging section gathers the laser outputs of multiple operating bands, allowing multiple operating bands to share the same output port. This effectively reduces device complexity, improves the integration of multi-band lasers, and facilitates subsequent packaging and system integration.

[0068] In some embodiments, the reflector 400 includes:

[0069] The first transmission arm 401 is used to transmit the first split beam of the propagating light and to transmit the first return light to the confluence unit 300.

[0070] The second transmission arm 402 is used to transmit the second split beam of the propagating light and to transmit the second return light.

[0071] A coupler, connected to the first transmission arm 401 and the second transmission arm 402 respectively, is used to transmit the first split beam and the second split beam into the ring waveguide 403, and to merge the first split beam and the second split beam transmitted back from the ring waveguide 403, and to split the merged beam into a first return beam and a second return beam, with the first return beam transmitted into the first transmission arm 401 and the second return beam transmitted into the second transmission arm 402.

[0072] The ring waveguide 403, connected to the coupler, is used to make the first split beam and the second split beam propagate in opposite directions along the ring waveguide 403.

[0073] The propagating light of any operating wavelength band transmitted from the converging part 300 to the reflecting part 400 is split into a first beam splitter and a second beam splitter, which are transmitted by the first transmission arm 401 and the second transmission arm 402, respectively. The first transmission arm 401 and the second transmission arm 402 can change the optical path difference between the first beam splitter and the second beam splitter. The first beam splitter and the second beam splitter are transmitted into the ring waveguide 403, so that the first beam splitter and the second beam splitter propagate towards each other along the ring waveguide 403.

[0074] The first and second beams transmitted back from the ring waveguide 403 merge, interfere with each other, and split the merging light into a first return beam and a second return beam. The first return beam is transmitted into the first transmission arm 401 and back to the gain medium, causing the propagating light to oscillate. The second return beam is transmitted into the second transmission arm 402 and further transmitted out to form the output light.

[0075] In some embodiments, the first transmission arm 401 is further used to change the optical path of the first beam splitter, and the second transmission arm 402 is further used to change the optical path of the second beam splitter, thereby changing the optical path difference between the first and second beam splitters, making the reflectivity of the reflector 400 adjustable for propagating light in at least two operating wavelengths. Changing the optical path difference between the first and second beam splitters can change the optical field of the first and second beam splitters entering the ring waveguide 403, as well as change their interference state, thereby adjusting the optical power returning to the converging section 300. In some embodiments, the first transmission arm 401 and the second transmission arm 402 change the optical path difference through thermo-optical or electro-optical methods.

[0076] The first transmission arm 401 and the second transmission arm 402 can be Mach-Zehnder interferometers, and the coupler and ring waveguide 403 can be Sagnac ring reflectors. In some embodiments, the reflector 400 can be one or a combination of several of the following: Sagnac ring reflector, Mach-Zehnder interferometer reflector, tunable Bragg grating reflector, tunable coupler reflector, thermo-optical tuned reflector structure, or electro-optical tuned reflector structure, or other structures capable of dynamically adjusting the external cavity feedback reflectivity, all of which are within the scope of protection of this invention.

[0077] In some embodiments, the multi-band laser further includes an output terminal 500 connected to the reflector 400 for outputting light. The output terminal 500 can be considered a common output terminal. In embodiments where the reflector 400 includes a first transmission arm 401 and a second transmission arm 402, the output terminal 500 and the second transmission arm 402 are connected.

[0078] The converging section 300 may employ, but is not limited to, optical interconnect structures with convergence functions such as a single bus waveguide, an arrayed waveguide grating (AWG), a star coupler, a multi-mode interference coupler (MMI), a tree-like Y-branch network, and a cascaded coupler. Any structure capable of achieving convergence of multiple independent wavelength bands, unified output, and the establishment of a common feedback optical path falls within the scope of protection of this invention.

[0079] The laser in this embodiment is suitable for hybrid integrated external cavity lasers with multiple communication bands, including but not limited to O-band, S-band, C-band, L-band, U-band, and other near-infrared communication bands. Different bands can be freely combined according to actual needs, and the number of gain media and filter components can also be increased or decreased according to application requirements.

[0080] The laser in this embodiment adopts a modular structure design. It can expand the working band by simply adding the corresponding gain medium and filter components. It has good scalability and can be flexibly expanded to multiple communication bands according to application requirements.

[0081] The multi-band laser provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of this invention.

Claims

1. A multi-band laser, characterized in that, include: A gain module includes at least two gain media, each of which corresponds to at least two operating wavelengths. The gain media are used to amplify the propagating light of the corresponding operating wavelength to which the light propagates. A filtering module includes at least two filtering components, which are connected one-to-one with the at least two gain media. The filtering components are used to select the frequency of the propagating light that propagates through the corresponding gain media. The confluence section is connected to the at least two filter components respectively, and is used to form output light from the propagating light that has passed through the at least two filter components.

2. The multi-band laser according to claim 1, characterized in that, The filtering component includes at least two microrings arranged sequentially, such that the propagating light passing through the at least two microrings is superimposed to form the frequency-selected propagating light, wherein the at least two microrings have different free spectral ranges.

3. The multi-band laser according to claim 1, characterized in that, The filtering component includes an input waveguide, the first to the Mth micro-rings, and the first to the (M-1)th bent waveguides, where M is a positive integer greater than or equal to 2; The input waveguide, the first to the Mth microrings and the first to the (M-1)th bent waveguides are arranged side by side, the first to the Mth microrings are arranged sequentially, the mth bent waveguide is arranged between the mth microring and the (m+1)th microring, m∈[1, M-1], the input waveguide is arranged on one side of the first microring, and the input waveguide is connected to the gain medium corresponding to the filter component.

4. The multi-band laser according to claim 3, characterized in that, The filtering component also includes an output waveguide; The confluence section includes a main waveguide, and the output waveguides of the at least two filter components are connected in series through the main waveguide.

5. The multi-band laser according to claim 1, characterized in that, The gain medium is also used to generate laser light corresponding to the operating wavelength, so that the laser light is optically amplified to form the propagating light corresponding to the operating wavelength.

6. The multi-band laser according to claim 1, characterized in that, Also includes: A reflecting part, connected to the converging part, is used to reflect at least part of the propagating light of any working band emitted from the converging part, so that the propagating light of any working band oscillates. The gain medium is also used to reflect the propagating light that has propagated to the gain medium, causing the propagating light to oscillate.

7. The multi-band laser according to claim 6, characterized in that, The reflectivity of the reflective element for the propagating light in the at least two working wavelengths is adjustable.

8. The multi-band laser according to claim 1, characterized in that, Also includes: A reflecting part, connected to the converging part, is used to reflect at least part of the propagating light of any working band emitted from the converging part, so that the propagating light of any working band oscillates. The reflective part includes: The first transmission arm is used to transmit the first split beam of the propagating light and to transmit the first return beam to the confluence. The second transmission arm is used to transmit the second split beam of the propagating light and to transmit the second return light. A coupler, connected to the first transmission arm and the second transmission arm respectively, is used to transmit the first split beam and the second split beam into the ring waveguide, and to merge the first split beam and the second split beam transmitted back from the ring waveguide, and to split the merged beam into the first return beam and the second return beam, the first return beam being transmitted into the first transmission arm and the second return beam being transmitted into the second transmission arm. The ring waveguide, connected to the coupler, is used to enable the first split beam and the second split beam to propagate in opposite directions along the ring waveguide.

9. The multi-band laser according to claim 8, characterized in that, The first transmission arm is also used to change the optical path of the first split beam, and the second transmission arm is also used to change the optical path of the second split beam, so as to change the optical path difference between the first split beam and the second split beam, so that the reflectivity of the reflective part for the propagation light of the at least two working wavelengths is adjustable.

10. The multi-band laser according to any one of claims 1 to 9, characterized in that, Also includes: The output end is connected to the reflector and is used to output light.

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