Laser chip, injection-locked laser and network device

Abstract

The present application provides a laser chip, an injection-locked laser, and a network device, and relates to the field of communication technology, in order to solve the problem of insufficient injection locking performance of the injection-locked laser. The laser chip provided by the present application includes: a first power monitor, a first controller, and a beam splitter, a polarization beam splitter rotator, a bandpass filter, and a slave laser connected in sequence; the injected light is injected into the slave laser after passing through the beam splitter, the polarization beam splitter rotator, and the bandpass filter; after the light beam generated by the slave laser passes through the bandpass filter, the polarization beam splitter rotator, and the beam splitter, a part of the light beam enters the first power monitor to monitor the power of the light beam, and the first controller is used to adjust the current and / or temperature of the slave laser according to the optical power of the light beam, so that the optical power monitored by the first power monitor reaches the first preset value, so as to achieve stable and efficient injection locking, thereby having good practicality.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a laser chip, an injection-locked laser and a network device. Background Art

[0002] With the rapid popularization of Internet video applications, the continuous development of high-bandwidth services such as 4K / 8K HD, home cloud and video calls, users' demand for communication capacity is increasing. This requires the laser as a light source to have higher optical power, lower threshold current, higher modulation bandwidth, lower relative intensity noise (Relative Intensity Noise, RIN), and higher linearity or narrower line width. Because traditional lasers are limited by chip materials or waveguide structures. Therefore, it is difficult to meet all of the above characteristics at the same time.

[0003] Injection locking technology provides a means to improve the performance of lasers from the outside, so that the lasers can meet the above characteristics at the same time. The main technical principle of injection locking lasers is: by injecting a laser with a wavelength close to that of the target slave laser cavity (this laser comes from the master laser), when the coupling strength between the master laser and the slave laser is high enough, the lasing wavelength of the slave laser can be locked to the lasing wavelength of the master laser. At this time, the phase difference between the lasers generated by the master laser and the slave laser is a constant value, thereby achieving injection locking.

[0004] The factors affecting injection locking mainly include the wavelength locking range of the injection-locked laser and the injection ratio of the master laser and the slave laser, as well as whether the polarization of the master laser and the slave laser are the same. In practical applications, it is difficult to ensure that the optical power injected by the master laser into each slave laser cavity is very strong, which may cause the slave laser to lose lock. For the polarization control of the master laser and the slave laser, the polarization state of the master laser is currently manually adjusted through a polarization controller to make the polarization of the master laser and the slave laser the same, which is not practical. Summary of the invention

[0005] The embodiments of the present application provide a laser chip, an injection-locked laser, and a network device to achieve stable and efficient injection locking, thereby having good practicality.

[0006] On the one hand, the present application provides a laser chip. The laser chip includes: a first power monitor, a first controller, and a beam splitter, a polarization beam splitter rotator, a bandpass filter, and a slave laser connected in sequence. The beam splitter includes a first port, a second port, and a third port. The first port is used to receive the injection light of the master laser, the second port is connected to the first power monitor, and the third port is connected to the polarization beam splitter rotator. The injected light enters the beam splitter from the first port and is output to the polarization beam splitter rotator from the third port. The polarization beam splitter rotator is used to split and polarize the injected light. Among them, the polarization beam splitter rotator includes a first waveguide and a second waveguide. After the injected light is split by the polarization beam splitter rotator, the first waveguide is used to transmit the TE mode injected light, and the second waveguide is used to transmit the TM mode injected light. After the TM mode injected light is converted into the TE mode injected light, the TE mode injected light of the first waveguide and the TE mode injected light of the second waveguide are output to the bandpass filter and injected into the slave laser. The light beam generated by the slave laser enters the optical splitter from the third port after passing through the bandpass filter and the polarization beam splitter rotator, and a portion of the light beam is output from the first port, and another portion of the light beam is output from the second port to the first power monitor. The first power monitor is used to monitor the optical power of the light output from the second port and generate a first monitoring signal. The first controller is used to adjust the current and / or temperature of the slave laser according to the first monitoring signal to change the emission wavelength of the slave laser so that the optical power monitored by the first power monitor reaches a first preset value (such as a maximum value).

[0007] In the laser chip provided in the present application, the injected light of the master laser can be efficiently injected into the slave laser, and under the action of the first power monitor and the first controller, the optical power of the slave laser can be effectively monitored, and the current and / or temperature of the slave laser can be automatically adjusted through the first monitoring signal generated by the first power monitor to achieve stable and efficient injection locking, thereby having good practicality.

[0008] In a specific implementation, the laser chip further includes a slave laser heater, which is used to control the temperature of the slave laser. The first controller is connected to the slave laser heater and is used to adjust the heating power of the slave laser heater according to the first monitoring signal to change the emission wavelength of the slave laser so that the optical power monitored by the first power monitor reaches the first preset value.

[0009] In practical applications, the slave laser heater may be a thermoelectric cooler, and the laser chip may be a silicon photonic chip on an SOI platform. Alternatively, the slave laser and the silicon photonic chip may also be a heterogeneous integrated structure.

[0010] In addition, in specific applications, the laser chip also includes a bandpass filter heater, a second power monitor and a second controller. The bandpass filter can be a silicon-based optical microring resonator, or a lithium niobate thin film microring resonator, a Mach-Zehnder interferometer resonator, etc. In addition, the microring resonator can be a single-order microring structure or a multi-order microring structure.

[0011] The bandpass filter heater is used to control the temperature of the bandpass filter, so that the center frequency of the bandpass filter can be changed to achieve alignment between the injection light frequency of the main laser and the center frequency of the bandpass filter, so that the injection light can be efficiently utilized. When the center frequency of the bandpass filter is adjusted, the second power monitor can select a certain proportion of the optical power to monitor the optical power filtered by the bandpass filter and generate a second monitoring signal. The second controller is connected to the second power monitor and the bandpass filter heater, and is used to adjust the heating power of the bandpass filter heater according to the second monitoring signal to change the center frequency of the bandpass filter so that the optical power monitored by the second power monitor reaches a second preset value (such as a minimum value).

[0012] In addition, when injection locking of the slave laser is achieved, the emission wavelength of the slave laser may be adjusted when the optical power received by the second power monitor is minimum.

[0013] Specifically, the first controller is also connected to the second power monitor. The first controller is used to adjust the current and / or temperature of the slave laser according to the first monitoring signal when the optical power monitored by the second power monitor reaches a second preset value (such as a minimum value) to change the emission wavelength of the slave laser so that the optical power monitored by the first power monitor reaches a first preset value (such as a maximum value).

[0014] In the above adjustment method, the center frequency of the bandpass filter can be adjusted first to align the center frequency of the bandpass filter with the center frequency of the injected light, so that the injected light can be used efficiently. Then, the emission wavelength of the slave laser is adjusted to align the emission wavelength of the slave laser with the wavelength of the injected light, so that stable and efficient injection locking of the slave laser can be achieved.

[0015] In addition, the laser chip also includes a combining structure, and the polarization beam splitter and the bandpass filter are connected through the combining structure, and the combining structure is used to combine the TE mode injection light of the two waveguides of the polarization beam splitter and transmit it to the bandpass filter.

[0016] In specific implementation, the wave combining structure can be a single-stage coupled waveguide or a plurality of cascaded coupled waveguides. Among them, the coupled waveguide can be a Y-coupled waveguide, a directional coupler waveguide or a multimode interferometer waveguide. In practical application, the type of coupled waveguide can be selected and adjusted accordingly according to actual needs, and this application does not limit it.

[0017] In addition, in order to achieve coherence enhancement of the two TE mode injected light beams after the combined light beams, the phases of the two TE mode injected light beams after the combined light beams may also be adjusted during the specific implementation.

[0018] For example, in one implementation, the laser chip further includes a wave combining heater, a third power monitor, and a third controller.

[0019] The wave combining heater is used to control the temperature of the wave combining structure to change the phase of the TE mode injected light in a certain path, so that the two beams of TE mode injected light after the wave combining are coherently enhanced, so that the optical power monitored by the third power monitor reaches the third preset value (such as the maximum value). Specifically, when the optical power monitored by the third power monitor reaches the third preset value, it means that the two beams of TE mode injected light after the wave combining are coherently enhanced. Thereby, the utilization efficiency of the injected light can be effectively improved.

[0020] It is understandable that, in a specific implementation, the wave combining structure may also include three, four or more cascaded coupling waveguides to achieve higher precision adjustment of the phase of the TE mode injected light. It is understandable that when the wave combining structure includes multiple cascaded coupling waveguides, the number of wave combining heaters is the same as the number of coupling waveguides, and one wave combining heater corresponds to one coupling waveguide. Alternatively, in some implementations, the wave combining structure may also include a single-stage coupling waveguide to reduce the difficulty and complexity of adjustment.

[0021] On the second aspect, the present application also provides an injection-locked laser, including a master laser, an isolator and any of the above-mentioned laser chips, wherein the injection light generated by the master laser enters the first port of the spectrometer after passing through the isolator, and is finally transmitted to the slave laser, thereby realizing injection locking of the slave laser. Among them, the isolator is an optical passive device for non-reciprocal transmission of light, and its basic function is to realize forward transmission of optical signals while suppressing reverse light. The injection light of the master laser is injected into the laser chip through the isolator, which can effectively prevent the reflected light generated by the slave laser from being transmitted to the master laser, thereby ensuring the working stability of the master laser.

[0022] In addition, the present application also provides a network device including the above-mentioned injection-locked laser. The network device may include a frequency division multiplexing device and the above-mentioned injection-locked laser, the signal of the frequency division multiplexing device is modulated into the injection-locked laser, and the injection-locked laser transmits the signal in the form of an optical signal. The injection-locked laser can be used as an optical network unit (Optical Network Unit, ONU) light source in a passive optical network system (Passive Optical Network, PON). Alternatively, the injection-locked laser can also be used in an optical line terminal (Optical Line Terminate, OLT). BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A structural block diagram of a laser chip provided in an embodiment of the present application;

[0024] Figure 2 A schematic diagram of the structure of a laser chip provided in an embodiment of the present application;

[0025] Figure 3 A schematic diagram of the structure of another laser chip provided in an embodiment of the present application;

[0026] Figure 4 A schematic diagram of the structure of another laser chip provided in an embodiment of the present application;

[0027] Figure 5 A schematic diagram of the structure of another laser chip provided in an embodiment of the present application;

[0028] Figure 6 A schematic diagram of the structure of another laser chip provided in an embodiment of the present application;

[0029] Figure 7 A structural block diagram of an injection-locked laser provided in an embodiment of the present application;

[0030] Figure 8 A system architecture diagram of a passive optical network provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present application more clear, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to be limiting of the present application. As used in the specification and the appended claims of the present application, the singular expressions "a", "an", "above", "the" are intended to also include expressions such as "one or more", unless there is a clear contrary indication in the context.

[0033] References to "one embodiment" and the like described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in other embodiments", etc. that appear at different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "include", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0034] Figure 1 A structural block diagram of a laser chip provided in an embodiment of the present application. The laser chip includes: a first power monitor 10, a first controller 20, a beam splitter 30, a polarization beam rotator 40, a bandpass filter 50 and a slave laser 60. Among them, the beam splitter 30, the polarization beam rotator 40, the bandpass filter 50 and the slave laser 60 are connected in sequence, and the first controller 20 is connected to the first power monitor 10 and the slave laser 60. The beam splitter 30 includes a first port (not shown in the figure), a second port (not shown in the figure) and a third port (not shown in the figure). The first port is used to receive the injected light of the master laser, the second port is connected to the first power monitor 10, and the third port is connected to the polarization beam rotator 40. The injected light enters the beam splitter 30 from the first port and is output to the polarization beam rotator 40 from the third port. The polarization beam rotator 40 is used to split and polarize the injected light.

[0035] Figure 2A schematic diagram of the structure of a laser chip provided in an embodiment of the present application. The injected light generally includes injected light of any polarization state (such as TE mode, TM mode, etc.). After the injected light is injected into the beam splitter 30 through the first port, it is output to the polarization beam splitter rotator 40 by the third port of the beam splitter 30. The polarization beam splitter rotator 40 first splits the injected light to separate the TE mode injected light and the TM mode injected light in the injected light, and then transmits the TE mode injected light and the TM mode injected light to the first waveguide and the second waveguide respectively for subsequent transmission. That is, the first waveguide is used to conduct the TE mode injected light, and the second waveguide is used to transmit the TM mode injected light. Subsequently, the polarization rotator 41 in the polarization beam splitter rotator 40 converts the TM mode injected light of the second waveguide into TE mode injected light, and then outputs the TE mode injected light of the first waveguide and the TE mode injected light of the second waveguide to the bandpass filter 50. That is, after the injected light of any polarization state passes through the polarization beam splitter rotator 40 , the injected light outputted from the two waveguides (the first waveguide and the second waveguide) of the polarization beam splitter rotator 40 are all TE mode injected light.

[0036] The bandpass filter 50 is used to filter the non-target frequency component clutter in the injected light, allowing the frequency components within a certain frequency range to pass through and effectively attenuating the frequency components within other frequency ranges. Optionally, the bandpass filter 50 can realize the function of calibrating the input wavelength, see Figure 3 The description of the related embodiments is not repeated here. After passing through the bandpass filter 50 , the injected light is finally injected into the slave laser 60 .

[0037] The light beam generated by the laser 60 enters the beam splitter 30 from the third port after passing through the bandpass filter 50 and the polarization beam splitter rotator 40 , and a portion of the light beam is output from the first port, and another portion of the light beam is output from the second port to the first power monitor 10 .

[0038] The first power monitor 10 is used to monitor the optical power of the second port and generate a first monitoring signal.

[0039] The first controller 20 is connected to the first power monitor 10, and is used to perform current regulation and / or temperature regulation on the slave laser 60 according to the first monitoring signal to change the emission wavelength of the slave laser 60 so that the optical power monitored by the first power monitor 10 reaches a first preset value (such as a maximum value), thereby achieving injection locking.

[0040] In the laser chip provided in the embodiment of the present application, the injected light of the master laser can be efficiently injected into the slave laser 60, and under the action of the first power monitor 10 and the first controller 20, the optical power of the slave laser 60 can be effectively monitored, and the current and / or temperature of the slave laser 60 can be automatically adjusted through the first monitoring signal generated by the first power monitor 10 to achieve stable and efficient injection locking, thereby having good practicality.

[0041] The optical splitter 30 is a passive device, also known as an optical splitter, which does not require external energy, but only requires input light.

[0042] In specific applications, the optical splitter 30 can be a 2*1 optical splitter. Specifically, the optical splitter 30 includes three ports, namely the first port, the second port and the third port. The first port and the third port can be used as input ports or as output ports. That is, the injection light of the main laser can be injected into the optical splitter 30 from the first port and output from the third port. The light beam from the laser 60 can be injected into the optical splitter 30 from the third port and output from the first port. The second port can be used as an output port. After the light beam from the laser 60 is injected into the optical splitter 30 from the third port, a part of the light beam can be output from the first port, and the other part of the light beam can be output from the second port. Among them, a small amount of light beam from the laser 60 can be output from the second port for the first power monitor 10 to monitor the optical power. Most of the light beams can be output from the first port to achieve efficient signal transmission.

[0043] It can be understood that, in a specific implementation, the type of the optical splitter 30 is not limited in this application.

[0044] The main function of the polarization beam splitter-rotator 40 (PSR) is to split the injected light and convert the TM mode injected light in the injected light into the TE mode injected light. In a specific implementation, the polarization beam splitter-rotator 40 can be an integrated device. That is, after the injected light of any polarization state passes through the polarization beam splitter-rotator 40, the injected light output by the two waveguides (the first waveguide and the second waveguide) of the polarization beam splitter-rotator 40 is the TE mode injected light. Alternatively, the polarization beam splitter-rotator 40 can also be composed of two separate devices, a beam splitter and a polarization rotator.

[0045] Among them, the beam splitter is an optical device that can split a beam of light into two or more beams of light, and is usually composed of a metal film or a dielectric film. When the injected light passes through the beam splitter, the TE mode injected light in the injected light will be output from one of the optical paths, and the TM mode injected light in the injected light will be output from the other optical path. The polarization rotator can adjust the polarization state of the light. Specifically, the TM mode injected light in the injected light is output from the other optical path of the beam splitter and then enters the polarization rotator. The polarization rotator deflects the TM mode injected light and finally converts the TM mode injected light into the TE mode injected light.

[0046] It is understood that, in a specific implementation, the polarization beam splitter rotator 40 may be an integrated device, or a device composed of a beam splitter and a polarization rotator. Alternatively, other devices capable of splitting and deflecting a light beam may be used, which is not limited here. It should be noted that, in order to facilitate the understanding of the technical solution of the present application, in the following embodiments, a device in which the polarization beam splitter rotator 40 is an integrated device will be used as an example for specific description.

[0047] In addition, in specific applications, the bandpass filter 50 can be a silicon-based optical microring resonator, or can also be a lithium niobate thin film microring resonator, a Mach-Zehnder interferometer resonator, etc. In addition, the microring resonator can be a single-order microring structure or a multi-order microring structure. In specific use, the type of the bandpass filter 50 can be selected and adjusted accordingly according to actual needs, and this application does not limit this.

[0048] The slave laser 60 may be a directly modulated semiconductor laser (DML), a continuous wave laser (CW laser), or other types of lasers, which are not limited in the present application.

[0049] In practical applications, in order to adjust the wavelength of the light beam generated by the slave laser 60, the current of the slave laser 60 may be adjusted by the first controller 20. Alternatively, the operating temperature of the slave laser 60 may also be adjusted.

[0050] Specifically, since the wavelength of the light beam generated by the slave laser 60 is related to the current and the operating temperature of the slave laser 60 , the wavelength of the light beam can be changed by adjusting the current and / or temperature.

[0051] In a specific implementation, the slave laser 60 can be a semiconductor laser with a semiconductor refrigerator 61 (TEC). The first controller 20 is connected to the semiconductor refrigerator 61, and is used to adjust the heating power of the semiconductor refrigerator 61 by controlling the current of the semiconductor refrigerator 61, thereby adjusting the working temperature of the slave laser 60, and then adjusting the wavelength of the light beam generated by the slave laser 60. When adjusting, the wavelength of the light beam can be adjusted by only changing the current of the slave laser 60, or by only changing the working temperature of the slave laser 60. Alternatively, the wavelength of the light beam can be adjusted by changing the current and working temperature of the slave laser 60 at the same time, so as to achieve efficient, stable and accurate adjustment.

[0052] In a specific application, the first controller 20 may include three functional units: an analog-to-digital-to-digital-to-analog conversion unit (AD / DA), a microcontroller unit (MCU) and an electric drive unit.

[0053] The first power monitor 10 may be a photodiode based on a Ge / Si structure, or may also be a III-V semiconductor chip or other types of optical power monitoring devices to achieve good monitoring of optical power.

[0054] In addition, the laser chip can be a silicon photonic chip of the SOI (Silicon-On-Insulator) platform, or a heterogeneous integrated photonic chip, etc. In specific applications, the integration type of the laser chip can be reasonably selected according to different requirements, and is not limited here.

[0055] When injection locking is performed, the first power monitor 10 can continuously or periodically monitor the optical power of the second port. The first controller 20 can adjust the current and operating temperature of the slave laser 60. When the optical power received by the first power monitor 10 is the maximum, it means that injection locking is achieved for the slave laser 60. At this time, the current current and operating temperature of the slave laser 60 are maintained to achieve stable and long-term injection locking.

[0056] Figure 3 This is a schematic diagram of the structure of another laser chip provided in an embodiment of the present application. Figure 3 As shown, in one embodiment provided in the present application, the laser chip further includes a bandpass filter heater 51 , a second power monitor 52 and a second controller 21 .

[0057] Since the center frequency of the bandpass filter 50 is related to the operating temperature, the center frequency of the bandpass filter 50 can be effectively adjusted by controlling the temperature of the bandpass filter 50. That is, the bandpass filter heater 51 is used to control the temperature of the bandpass filter 50, so that the center frequency of the bandpass filter 50 can be changed to achieve alignment between the injection light frequency of the main laser and the center frequency of the bandpass filter 50, so that the injection light can be efficiently utilized.

[0058] When adjusting the center frequency of the bandpass filter 50, the second power monitor 52 can select a certain proportion (such as 5%) of the optical power to monitor the optical power filtered by the bandpass filter 50 and generate a second monitoring signal. The second controller 21 is connected to the second power monitor 52 and the bandpass filter heater 51, and is used to adjust the heating power of the bandpass filter heater 51 according to the second monitoring signal to change the center frequency of the bandpass filter 50 so that the optical power monitored by the second power monitor 52 reaches a second preset value (such as a minimum value).

[0059] In specific applications, the second controller 21 may include three functional units: an analog-to-digital-to-digital-to-analog conversion unit (AD / DA), a microcontroller unit (MCU) and an electric drive unit.

[0060] The type of the second power monitor can be the same as that of the first power monitor, which will not be described in detail here. The second power monitor can continuously or periodically monitor the optical power filtered by the bandpass filter 50. The second controller 21 can adjust the power of the bandpass filter heater 51 to change the operating temperature of the bandpass filter 50. When the optical power received by the second power monitor 52 is minimum, it means that the injection optical frequency of the main laser is aligned with the center frequency of the bandpass filter 50. At this time, the current heating power of the bandpass filter heater 51 can be maintained to achieve stable and long-term frequency alignment.

[0061] In addition, when injection locking of the slave laser 60 is achieved, the emission wavelength of the slave laser 60 may be adjusted when the optical power received by the second power monitor 52 is minimum.

[0062] Specifically, the first controller 20 is also connected to the second power monitor 52. The first controller 20 is used to adjust the current and / or temperature of the slave laser 60 according to the first monitoring signal when the optical power monitored by the second power monitor 52 reaches a second preset value (such as a minimum value) to change the emission wavelength of the slave laser 60 so that the optical power monitored by the first power monitor 10 reaches a first preset value (such as a maximum value).

[0063] In the above adjustment method, the center frequency of the bandpass filter 50 can be adjusted first, so that the center frequency of the bandpass filter 50 is aligned with the center frequency of the injected light, so that the injected light can be efficiently used. Then, the emission wavelength of the slave laser 60 is adjusted, so that the emission wavelength of the slave laser 60 is aligned with the wavelength of the injected light, so that stable and efficient injection locking can be achieved for the slave laser 60.

[0064] In addition, in specific applications, when the injected light passes through the polarization beam splitter rotator 40, the TM mode injected light in the injected light needs to be converted into TE mode injected light. After the conversion is completed, the two beams of TE mode injected light need to be combined through a combining structure and then transmitted to the bandpass filter 50.

[0065] Specifically, in one embodiment provided in the present application, the laser chip also includes a combining structure, which is connected to the polarization beam splitter rotator 40 and the bandpass filter 50, and is used to combine the TE mode injection light of the two waveguides of the polarization beam splitter rotator 40 and transmit it to the bandpass filter 50.

[0066] In a specific implementation, the wave combining structure may include a single-stage coupled waveguide or a plurality of cascaded coupled waveguides. The coupled waveguide includes a Y-coupled waveguide, a directional coupler waveguide or a multimode interferometer waveguide. In practical applications, the type of coupled waveguide may be selected and adjusted accordingly according to actual needs, and this application does not limit this.

[0067] In addition, in order to achieve coherence enhancement of the two TE mode injected light beams after the combined light beams, the phases of the two TE mode injected light beams after the combined light beams may also be adjusted during the specific implementation.

[0068] Figure 4 This is a schematic diagram of the structure of another laser chip provided in an embodiment of the present application. Figure 4 As shown, the combining structure includes two cascaded first coupling waveguides 70 and second coupling waveguides 80. Among them, the first coupling waveguide 70 is a 2*2 directional coupler waveguide or a multimode interferometer waveguide. The second coupling waveguide 80 is a Y-coupled waveguide. The first coupling waveguide 70 has two input ends and two output ends. The two input ends are respectively used to connect the two TE mode waveguides of the polarization beam splitter rotator 40, and after being combined by the first coupling waveguide 70, they are output from the two output ends to the second coupling waveguide 80 for re-combining. Before the combining process, the phase of one of the TE mode injection lights can be adjusted by temperature control to achieve coherence enhancement of the two TE mode injection lights after combining.

[0069] Specifically, in the embodiment provided in the present application, the laser chip further includes a first wave-combining heater 71 , a second wave-combining heater 81 , a third power monitor 90 and a third controller 22 .

[0070] The first wave combining heater 71 is used to control the temperature of the first coupling waveguide 70 to change the phase of the TE mode injected light in the path. The second wave combining heater 81 is used to control the temperature of the second coupling waveguide 80 to change the phase of the TE mode injected light in the path so that the optical power monitored by the third power monitor 90 reaches a third preset value (such as a maximum value). Specifically, when the optical power monitored by the third power monitor reaches the third preset value, it means that the two beams of TE mode injected light after combining have achieved coherent enhancement. Thereby, the utilization efficiency of the injected light can be effectively improved.

[0071] It is understandable that, in other embodiments, the wave combining structure may also include three, four or more cascaded coupling waveguides to achieve higher precision adjustment of the phase of the TE mode injected light.

[0072] Figure 5 A schematic diagram of the structure of another laser chip provided in an embodiment of the present application. The wave combining structure includes three cascaded first coupling waveguides 70, second coupling waveguides 80 and third coupling waveguides 82. The first coupling waveguide 70 and the third coupling waveguide are 2*2 directional coupler waveguides or multimode interferometer waveguides. The second coupling waveguide 80 is a Y-coupled waveguide.

[0073] The first coupling waveguide 70 has two input ends and two output ends. The two input ends are respectively used to connect the two TE mode waveguides of the polarization beam splitter rotator 40. After being combined by the first coupling waveguide 70, the two output ends are output to the third coupling waveguide 82 for further combination. After passing through the third coupling waveguide 82, the two output ends are output to the second coupling waveguide 80 for further combination.

[0074] Among them, the first wave combining heater 71 is used to control the temperature of the first coupling waveguide 70 to change the phase of the TE mode injected light in the path. The third wave combining heater 83 is used to control the temperature of the third coupling waveguide 82 to change the phase of the TE mode injected light in the path. The second wave combining heater 81 is used to control the temperature of the second coupling waveguide 80 to change the phase of the TE mode injected light in the path so that the optical power monitored by the third power monitor 90 reaches a third preset value (such as a maximum value). Specifically, when the optical power monitored by the third power monitor reaches the third preset value, it means that the two beams of TE mode injected light after combining have achieved coherent enhancement. Thereby, the utilization efficiency of the injected light can be effectively improved.

[0075] It should be understood that when the wave combining structure includes a plurality of cascaded coupled waveguides, the number of the wave combining heaters is the same as the number of the coupled waveguides, and one wave combining heater corresponds to one coupled waveguide. Alternatively, in some embodiments, the wave combining structure may also include a single-stage coupled waveguide to reduce the difficulty and complexity of adjustment.

[0076] For example, Figure 6 This is a schematic diagram of the structure of another laser chip provided in an embodiment of the present application. Figure 6 As shown, in another embodiment provided by the present application, the second coupling waveguide is omitted in the wave combining structure, that is, the wave combining structure combines waves only through the first coupling waveguide 70. Through the form of a single-stage coupling waveguide, the difficulty and complexity of adjustment can be significantly reduced, which is conducive to reducing costs and R&D investment.

[0077] In specific applications, the third controller 22 may include three functional units: an analog-to-digital-to-digital-to-analog conversion unit (AD / DA), a microcontroller unit (MCU) and an electric drive unit.

[0078] The specific type of the third power monitor may be the same as that of the first power monitor, which will not be described in detail herein.

[0079] It is understandable that when the laser chip includes the first controller 20, the second controller 21 and the third controller 22, the three controllers may be separate devices or may share a multi-channel micro control unit and an electric drive unit.

[0080] In a specific implementation, the types and configuration relationships of the first controller 20 , the second controller 21 , and the third controller 22 can be adaptively adjusted according to different requirements, and this application does not limit this.

[0081] in addition, Figure 7 This is a structural block diagram of an injection locked laser provided in an embodiment of the present application. Figure 7 As shown, an embodiment of the present application further provides an injection-locked laser, comprising a master laser, an isolator, and any one of the laser chips in the above embodiments.

[0082] In specific implementation, the main laser can be FP laser, DFB laser, DBR laser, EML laser and other types. FP laser is a semiconductor light-emitting device that uses FP cavity as resonant cavity and emits multi-longitudinal mode coherent light. It has the characteristics of large output light power, small divergence angle, narrow spectrum, and low modulation rate, and is suitable for long-distance communication. DFB laser uses grating filter device on the basis of FP laser, so that the device has only one longitudinal mode output. The device has the characteristics of large output light power, small divergence angle, extremely narrow spectrum, and low modulation rate, and is suitable for long-distance communication. DBR laser uses Bragg grating as a reflector, encapsulates a doped fiber between two Bragg gratings, and provides gain by pumping the doped fiber in the middle. EML laser has the advantages of low cost and low power consumption, and also has good advantages in chirp effect, extinction ratio, transmission distance and other performances, and can achieve high-speed and long-distance transmission.

[0083] It is understandable that, in specific implementation, the type of the main laser can be selected and adjusted according to actual conditions, and this application does not limit this.

[0084] The isolator is an optical passive device for non-reciprocal light transmission. Its basic function is to realize the forward transmission of the light beam while suppressing the reverse light. The injection light of the main laser is injected into the laser chip through the isolator, which can effectively prevent the reflected light generated by the laser 60 from being transmitted to the main laser, thereby ensuring the working stability of the main laser.

[0085] In practical applications, injection-locked lasers can be applied to a variety of network devices to achieve the purpose of signal transmission.

[0086] Figure 8 A system architecture diagram of a passive optical network provided in an embodiment of the present application. Figure 8As shown, a passive optical network (PON) includes: an optical line terminal 01 (OLT) and several optical network units 02 (ONUs). The injection-locked laser can be used as a light source in ONU 2. The injection light generated by the main laser passes through the optical distribution network (ODN) and is injected into the injection-locked laser to achieve injection locking. The signal of the frequency division multiple access device 021 (Frequency Division Multiple Access, FDMA) is modulated onto the injection-locked laser. The signal light emitted by the injection-locked laser passes through the optical fiber and the optical distribution network to reach OLT 01, and is coherently received and signal processed by relevant devices in OLT 01 (such as data selector 011, digital signal processor 012, etc.) to parse out the optical signal of each ONU 02.

[0087] Passive optical network means that there is no active electronic device in the ODN between OLT 01 and ONU 02. Generally, the downlink adopts time division multiplexing broadcast mode, and the uplink adopts time division multiple access mode, and it can flexibly form tree, star and bus topologies. The typical structure is a tree structure. Each ONU 02 can share the optical fiber between OLT 01 and the optical splitter, which saves the amount of optical fiber laying, has good service transparency, and can be applied to signals of any standard and rate in principle, which is easy to expand and maintain the network. As the key components of the optical network, OLT 01 and ONU 02 are responsible for the task of photoelectric conversion and transmission of network signals, which is the basis for the normal communication of the entire network.

[0088] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A laser chip, characterized in that: include: A first power monitor, a first controller, and a sequentially connected optical splitter, a polarization beam splitter rotator, a bandpass filter, and a slave laser; The optical splitter comprises a first port, a second port and a third port; the first port is used to receive the injection light of the main laser, the second port is connected to the first power monitor, and the third port is connected to the polarization beam splitter rotator; The injected light enters the optical splitter through the first port and is output to the polarization beam splitter rotator through the third port; The polarization beam splitter rotator is used to split and polarize the injected light; Wherein, the polarization beam splitter rotator comprises a first waveguide and a second waveguide, after the injected light is split by the polarization beam splitter rotator, the first waveguide is used to transmit the TE mode injected light, and the second waveguide is used to transmit the TM mode injected light, after the TM mode injected light is converted into the TE mode injected light, the TE mode injected light of the first waveguide and the TE mode injected light of the second waveguide are output to the bandpass filter and injected into the slave laser; the light beam generated by the slave laser enters the beam splitter from the third port after passing through the bandpass filter and the polarization beam splitter rotator, and a part of the light beam is output from the first port, and another part of the light beam is output from the second port to the first power monitor; The first power monitor is used to monitor the optical power of the light output by the second port and generate a first monitoring signal; The first controller is used to adjust the current and / or temperature of the slave laser according to the first monitoring signal to change the emission wavelength of the slave laser so that the optical power monitored by the first power monitor reaches a first preset value; The laser chip also includes a bandpass filter heater, a second power monitor and a second controller; The band-pass filter heater is used to control the temperature of the band-pass filter to change the center frequency of the band-pass filter; The second power monitor is used to monitor the optical power filtered by the bandpass filter and generate a second monitoring signal; The second controller is connected to the second power monitor and the bandpass filter heater, and is used to adjust the heating power of the bandpass filter heater according to the second monitoring signal to change the center frequency of the bandpass filter so that the optical power monitored by the second power monitor reaches a second preset value.

2. The laser chip according to claim 1, characterized in that: The first controller is also connected to the second power monitor; The first controller is used to adjust the current and / or temperature of the slave laser according to the first monitoring signal when the optical power monitored by the second power monitor reaches a second preset value, so as to change the emission wavelength of the slave laser so that the optical power monitored by the first power monitor reaches a first preset value.

3. The laser chip according to claim 1 or 2, characterized in that: The laser chip also includes a wave combining structure, through which the polarization beam splitter and the bandpass filter are connected, and the wave combining structure is used to combine the TE mode injection light of the two waveguides of the polarization beam splitter and transmit it to the bandpass filter.

4. The laser chip according to claim 3, characterized in that: The wave combining structure includes a plurality of cascaded coupled waveguides.

5. The laser chip according to claim 4, characterized in that: The coupling waveguide is a Y-coupled waveguide, a directional coupler waveguide or a multimode interferometer waveguide.

6. The laser chip according to claim 4 or 5, characterized in that: The laser chip also includes a wave combining heater, a third power monitor and a third controller; The wave combining heater is used to control the temperature of the wave combining structure to change the phase of the TE mode injected light output by the second waveguide so that the optical power monitored by the third power monitor reaches a third preset value.

7. The laser chip according to claim 6, characterized in that: When the wave combining structure includes a plurality of cascaded coupled waveguides, the number of the wave combining heaters is the same as the number of the coupled waveguides, and one wave combining heater corresponds to one coupled waveguide.

8. The laser chip according to claim 1 or 2, characterized in that: The laser chip also includes a slave laser heater; The slave laser heater is used to control the temperature of the slave laser; Wherein, the first controller is connected to the slave laser heater and is used to adjust the heating power of the slave laser heater according to the first monitoring signal to change the emission wavelength of the slave laser so that the optical power monitored by the first power monitor reaches the first preset value.

9. The laser chip according to claim 8, characterized in that: The slave laser heater is a thermoelectric cooler.

10. The laser chip according to claim 1 or 2, characterized in that: The laser chip is a silicon photonic chip on an SOI platform.

11. The laser chip according to claim 10, characterized in that: The slave laser and the silicon photonic chip are a heterogeneous integrated structure.

12. The laser chip according to claim 1 or 2, characterized in that: The bandpass filter is any one of a microring resonant cavity and a Mach-Zehnder interferometer resonant cavity.

13. An injection locked laser, characterized in that: A laser chip comprising a master laser, an isolator and any one of claims 1 to 12; The injection light generated by the main laser enters the first port of the optical splitter after passing through the isolator.

14. A network device, characterized in that: It comprises a frequency division multiplexing device and the injection locking laser as claimed in claim 13, wherein the signal of the frequency division multiplexing device is modulated into the injection locking laser, and the injection locking laser transmits the signal in the form of an optical signal.

15. The network device according to claim 14, characterized in that: The network device is an optical line terminal device or an optical network unit device.

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