阅读说明：本技术 基于负热光系数硫系微腔的孤子频梳自产生系统及方法 (Soliton frequency comb self-generating system and method based on negative thermo-optic coefficient chalcogenide microcavity ) 是由 张斌 吴家越 李朝晖 夏迪 赵佳鑫 王自富 于 2021-08-30 设计创作，主要内容包括：本发明公开一种基于负热光系数硫系微腔的孤子频梳自产生系统及方法,可调谐激光器发射出预设波长和功率的泵浦光,经过光纤放大器调节功率后输入到偏振控制器,偏振控制器将泵浦光的偏振态调节为与负热光系数微环谐振腔的设计偏振模式相一致,经过可调谐光衰减器,控制泵浦光进入负热光系数微环谐振腔；设置泵浦光在谐振峰频率附近进行频率调谐,随着微环谐振腔内部快速热量累积,负热光系数微环谐振腔的谐振峰出现蓝移效应,呈现出谐振峰蓝失谐处能量变化陡峭,红失谐处能量变化缓慢。通过使用本发明,实现高效率的孤子频梳自产生,且频梳的稳定性更高。本发明可广泛应用于光电技术领域。(The invention discloses a soliton frequency comb self-generating system and a soliton frequency comb self-generating method based on a negative thermo-optic coefficient chalcogenide microcavity.A tunable laser emits pump light with preset wavelength and power, the pump light is input into a polarization controller after the power of the pump light is adjusted by an optical fiber amplifier, the polarization state of the pump light is adjusted by the polarization controller to be consistent with the designed polarization mode of the negative thermo-optic coefficient micro-ring resonant cavity, and the pump light is controlled to enter the negative thermo-optic coefficient micro-ring resonant cavity through a tunable optical attenuator; the frequency tuning is carried out by setting the pump light near the resonant peak frequency, and along with the rapid heat accumulation in the micro-ring resonant cavity, the blue shift effect appears on the resonant peak of the negative thermo-optic coefficient micro-ring resonant cavity, so that the energy change at the blue detuning part of the resonant peak is steep, and the energy change at the red detuning part is slow. By using the invention, the self-generation of the high-efficiency soliton frequency comb is realized, and the stability of the frequency comb is higher. The invention can be widely applied to the technical field of photoelectricity.)

1. The soliton frequency comb self-generating method based on the negative thermo-optic coefficient chalcogenide microcavity is characterized by comprising the following steps of:

the tunable laser emits pump light with preset wavelength and power, the power of the pump light is adjusted by the optical fiber amplifier and then the pump light is input into the polarization controller, the polarization controller adjusts the polarization state of the pump light to be consistent with the polarization mode of the negative thermo-optical coefficient micro-ring resonant cavity, and the pump light is controlled to enter the negative thermo-optical coefficient micro-ring resonant cavity by the tunable optical attenuator;

setting pump light to perform frequency tuning near the resonant peak frequency of the negative thermo-optic coefficient micro-ring resonant cavity, wherein the resonant peak of the negative thermo-optic coefficient micro-ring resonant cavity has a blue shift effect along with rapid heat accumulation in the micro-ring resonant cavity, so that energy change at a blue detuning part of the resonant peak is steep, and energy change at a red detuning part is slow;

when laser frequency enters the micro-ring resonant cavity from the red detuning position of the resonant peak, the red detuning region can realize self-heating locking of detuning quantity due to the negative thermo-optic effect of the microcavity, the fact that pump light can exist in the red detuning region of the microcavity stably is guaranteed, the detuning quantity meets the excitation condition of dissipating Kerr solitons, and therefore soliton frequency comb can be generated stably and rapidly.

2. The soliton frequency comb self-generating system based on the negative thermo-optic coefficient chalcogenide microcavity is characterized by comprising the following components:

the system comprises a tunable laser, an optical fiber amplifier, a polarization controller, a negative thermo-optic coefficient micro-ring resonant cavity, a tunable optical attenuator, a spectrum analyzer, an oscilloscope and an electric signal analyzer;

the tunable laser, the optical fiber amplifier, the polarization controller, the negative thermo-optic coefficient micro-ring resonant cavity and the tunable optical attenuator are sequentially connected through a single mode fiber, and the tunable optical attenuator is respectively connected with the optical spectrum analyzer, the oscilloscope and the electric signal analyzer.

3. The soliton frequency comb self-generating system based on the negative thermo-optic coefficient chalcogenide microcavity as claimed in claim 2, wherein the negative thermo-optic coefficient micro-ring resonator comprises a micro-ring resonator, a straight waveguide and a pulley coupling region, and the micro-ring resonator and the straight waveguide are optically field coupled through the pulley coupling region.

4. The soliton frequency comb self-generating system based on the negative thermo-optic coefficient chalcogenide microcavity is characterized in that the micro-ring resonator and the straight waveguide respectively comprise a cladding layer, a core layer and a substrate from top to bottom, the substrate comprises but is not limited to silicon, quartz, lithium niobate, calcium fluoride and the like, the core layer is made of the low thermo-optic coefficient chalcogenide material, the cladding layer is made of the negative thermo-optic coefficient chalcogenide material, the cladding layer covers the core layer and is connected with the substrate, and the refractive index of the cladding layer and the refractive index of the substrate material are both smaller than the refractive index of the core layer.

5. The soliton frequency comb self-generating system based on the negative thermo-optic coefficient chalcogenide microcavity As claimed in claim 4, wherein the negative thermo-optic coefficient chalcogenide material component is As_xS_100-x(5. ltoreq. x. ltoreq.35) or As_xSe_100-x(x is more than or equal to 5 and less than or equal to 35), and the low-thermo-optic coefficient chalcogenide material component is Ge_xSb₁₀S_90-x(5≤x≤35)。

6. The soliton frequency comb self-generating system based on the negative thermo-optical coefficient chalcogenide microcavity is characterized in that the straight waveguide is provided with an input port and an output port, a pump light signal enters the straight waveguide from the input port and is coupled into the micro-ring resonant cavity to generate a nonlinear effect, and then a light frequency comb signal is generated and is coupled with the straight waveguide and finally output from the output port.

7. The soliton frequency comb self-generating system based on the negative thermo-optic coefficient chalcogenide microcavity as claimed in claim 6, wherein the input port and the output port of the straight waveguide are both provided with inverted tapered waveguide couplers for receiving the pump light and outputting the generated optical frequency comb.

8. The soliton frequency comb self-generating system based on the negative thermo-optic coefficient chalcogenide microcavity according to claim 4, wherein the quality factor of the micro-ring resonator is greater than 10^ 5.

Technical Field

The invention belongs to the technical field of photoelectricity, and particularly relates to a system and a method for self-generating an soliton frequency comb based on a negative thermo-optic coefficient chalcogenide microcavity.

Background

The optical frequency comb is composed of a series of equally spaced and phase-locked optical frequencies, which are spectrally represented as a comb-shaped spectrum and temporally represented as an electromagnetic field oscillation envelope having a time width on the order of femtoseconds. The optical frequency comb has the advantages of high precision, high resolution and high precision in frequency and time, and has extremely important application in the fields of optical atomic clocks, chemical detection, coherent optical communication, optical radar ranging and the like. The optical frequency comb based on the micro-resonant cavity is generated by Kerr nonlinearity of the optical resonant microcavity, has extremely small volume and power consumption, and is hopeful to realize the chip-level integrated optical frequency comb with lower power consumption.

The existing method for generating soliton frequency comb is that pumping light enters into the micro-ring resonant cavity from the blue shift direction of the resonant peak, and as the pumping light power in the micro-ring resonant cavity is gradually increased, a turing light frequency comb, a modulation instability light frequency comb and a soliton light frequency comb are obtained in sequence. However, the platform for preparing the micro-ring resonant cavity is mainly made of positive thermo-optic coefficient materials and has strong thermo-optic effect. In the optical frequency comb generation process, energy conversion at a blue detuning part of the micro-ring resonant cavity is slow, energy change at a red detuning part is steep and rapid, so that energy change in a resonant peak when a pumping wavelength enters the red detuning part is severe, a soliton generation area at the red detuning part is short and difficult to lock, and the existing optical soliton frequency comb is difficult to generate quickly and poor in stability.

Disclosure of Invention

In order to solve the above technical problems, an object of the present invention is to provide a system and a method for self-generating an soliton frequency comb based on a negative thermo-optic coefficient chalcogenide microcavity, which can achieve high-efficiency self-generation of soliton frequency comb and have higher stability of frequency comb.

A soliton frequency comb self-generating method based on a negative thermo-optic coefficient chalcogenide microcavity comprises the following steps:

the tunable laser emits pump light with preset wavelength and power, the power of the pump light is adjusted by the optical fiber amplifier and then the pump light is input into the polarization controller, the polarization controller adjusts the polarization state of the pump light to be consistent with the designed polarization mode of the negative thermo-optical coefficient micro-ring resonant cavity, and the pump light is controlled to enter the negative thermo-optical coefficient micro-ring resonant cavity by the tunable optical attenuator;

setting pump light to perform frequency tuning near the resonant peak frequency, wherein the resonant peak of the negative thermo-optic coefficient micro-ring resonant cavity has a blue shift effect along with rapid heat accumulation in the micro-ring resonant cavity, so that energy change at a blue detuning part of the resonant peak is steep, and energy change at a red detuning part is slow;

when laser frequency enters the micro-ring resonant cavity from a red detuning position of a resonant peak, the red detuning region can realize self-heating locking of detuning quantity due to the negative thermo-optic effect of the microcavity, the fact that pump light can exist in the red detuning region of the microcavity stably is guaranteed, the detuning quantity meets the excitation condition of dissipating Kerr solitons, and therefore soliton frequency comb can be generated stably and rapidly.

A soliton frequency comb self-generating system based on a negative thermo-optic coefficient chalcogenide microcavity comprises:

the system comprises a tunable laser, an optical fiber amplifier, a polarization controller, a negative thermo-optic coefficient micro-ring resonant cavity, a tunable optical attenuator, a spectrum analyzer, an oscilloscope and an electric signal analyzer;

the tunable laser, the optical fiber amplifier, the polarization controller, the negative thermo-optic coefficient micro-ring resonant cavity and the tunable optical attenuator are sequentially connected through a single mode fiber, and the tunable optical attenuator is respectively connected with the optical spectrum analyzer, the oscilloscope and the electric signal analyzer.

Further, the negative thermo-optical coefficient micro-ring resonant cavity comprises a micro-ring resonant cavity, a straight waveguide and a pulley coupling area, and the micro-ring resonant cavity and the straight waveguide are subjected to optical field coupling through the pulley coupling area.

Further, the micro-ring resonant cavity and the straight waveguide both comprise a negative thermal optical coefficient chalcogenide material cladding, a low thermal optical coefficient chalcogenide material core layer and a substrate which comprises but is not limited to materials such as silicon, quartz, lithium niobate and calcium fluoride, the negative thermal optical coefficient chalcogenide material cladding and the low thermal optical coefficient chalcogenide material core layer are arranged on the substrate, the core layer is covered and connected with the substrate by the negative thermal optical coefficient chalcogenide material cladding, and the refractive index of the negative thermal optical coefficient chalcogenide material cladding and the refractive index of the substrate material are both smaller than the refractive index of the core layer.

Furthermore, the input port and the output port of the straight waveguide are both provided with inverted conical waveguide couplers for receiving the pump light and outputting the generated light frequency comb.

Further, the negative thermo-optical coefficient chalcogenide material comprises As_xS_100-x(5. ltoreq. x. ltoreq.35) or As_xSe_100-x(x is more than or equal to 5 and less than or equal to 35), and the low-thermo-optic coefficient chalcogenide material component is Ge_xSb₁₀S_90-x(5≤x≤35)。

Furthermore, the quality factor of the micro-ring resonant cavity needs to be larger than 10^ 5.

The method and the system have the beneficial effects that: according to the invention, the sulfur system microcavity with a negative thermo-optic coefficient is introduced as a core device for soliton optical frequency comb generation, the thermal detuning curve of a resonance peak is regulated and controlled through the negative thermo-optic effect of the microcavity, the generation area of the soliton frequency comb is effectively increased, and the fast and stable generation of the soliton frequency comb is promoted. Compared with the conventional frequency comb generation method, the method can more stably and quickly lock the pumping frequency of the soliton frequency comb, realizes the self-generation of the soliton frequency comb, and has higher generation efficiency and higher stability of the frequency comb.

Drawings

FIG. 1 is a schematic structural diagram of an soliton frequency comb self-generating system based on a negative thermo-optic coefficient chalcogenide microcavity according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a negative-thermal-coefficient compensation micro-ring resonator according to an embodiment of the present invention;

FIG. 3 is a schematic view of a pulley coupling area under an enlarged condition in accordance with an embodiment of the present invention;

FIG. 4 is a schematic cross-sectional view of a negative thermal light envelope in accordance with an embodiment of the present invention;

FIG. 5 is a schematic diagram of negative thermo-optic resonance peak shift according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of the negative thermo-optic soliton existence region according to the embodiment of the present invention.

Reference numerals: 1. a micro-ring resonant cavity; 2. a straight waveguide; 3. a negative thermo-optic cladding; 4. a sulfur-based material; 5. a substrate.

Detailed Description

The invention is described in further detail below with reference to the figures and the specific embodiments. The step numbers in the following embodiments are provided only for convenience of illustration, the order between the steps is not limited at all, and the execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

A soliton frequency comb self-generating method based on a negative thermo-optic coefficient chalcogenide microcavity comprises the following steps:

the tunable optical attenuator emits pump light with preset wavelength and power, the power of the pump light is adjusted by the optical fiber amplifier and then the pump light is input into the polarization controller, the polarization controller adjusts the polarization state of the pump light to be consistent with the designed polarization mode of the negative thermo-optical coefficient micro-ring resonant cavity, and the pump light is controlled to enter the negative thermo-optical coefficient micro-ring resonant cavity by the tunable optical attenuator;

setting pump light to perform frequency tuning near the resonant peak frequency, wherein the resonant peak of the negative thermo-optic coefficient micro-ring resonant cavity has a blue shift effect along with rapid heat accumulation in the micro-ring resonant cavity, so that energy change at a blue detuning part of the resonant peak is steep, and energy change at a red detuning part is slow;

when laser frequency enters the micro-ring resonant cavity from the red detuning position of the resonant peak, the red detuning region can realize self-heating locking of detuning quantity due to the negative thermo-optic effect of the microcavity, the fact that pump light can exist in the red detuning region of the microcavity stably is guaranteed, the detuning quantity meets the excitation condition of dissipating Kerr solitons, and therefore soliton frequency comb can be generated stably and rapidly.

As shown in fig. 1, the present invention provides a negative thermo-optic coefficient chalcogenide microcavity-based soliton frequency comb self-generating system, which includes:

the system comprises a tunable laser, an optical fiber amplifier, a polarization controller, a negative thermo-optic coefficient micro-ring resonant cavity, a tunable optical attenuator, a spectrum analyzer, an oscilloscope and an electric signal analyzer;

the tunable laser, the optical fiber amplifier, the polarization controller, the negative thermo-optic coefficient micro-ring resonant cavity and the tunable optical attenuator are sequentially connected through a single mode fiber, and the tunable optical attenuator is respectively connected with the optical spectrum analyzer, the oscilloscope and the electric signal analyzer.

Specifically, the optical fiber amplifier is a Raman optical fiber amplifier; the polarization controller is an optical fiber polarization controller or a slide type polarization controller; the temperature regulator is a semiconductor refrigerator or a surface metal heater.

Further as a preferred embodiment of the present invention, the negative thermo-optic coefficient micro-ring resonator includes a micro-ring resonator, a straight waveguide, and a pulley coupling region, and the micro-ring resonator and the straight waveguide perform optical field coupling through the pulley coupling region.

Specifically, a schematic diagram of a negative thermo-optic coefficient micro-ring resonator is shown in fig. 2, and a schematic diagram of a pulley coupling region is shown in fig. 3.

Further as a preferred embodiment of the present invention, the micro-ring resonator and the straight waveguide both include a negative thermal optical coefficient chalcogenide cladding, a low thermal optical coefficient chalcogenide core, and a substrate including but not limited to silicon, quartz, lithium niobate, calcium fluoride, and the like, the substrate is provided with the negative thermal optical coefficient chalcogenide cladding and the low thermal optical coefficient chalcogenide core, the cladding covers the core and is connected to the substrate, and both the refractive index of the cladding and the refractive index of the substrate material are smaller than the refractive index of the core material.

Further as a preferred embodiment of the present invention, the input port and the output port of the straight waveguide are both provided with an inverted tapered waveguide coupler for receiving the pump light and outputting the generated optical frequency comb.

Further As a preferred embodiment of the present invention, the negative thermal coefficient chalcogenide material component is As₂₅S₇₅Or As₂₀Se₈₀。

Further, as a preferred embodiment of the present invention, the quality factor of the micro-ring resonator needs to be greater than 10^ 5.

Negative thermo-optic structure referring to fig. 4, the waveguide structure utilizes a low thermo-optic coefficient Ge₂₅Sb₁₀S₆₅The material is used as a core layer material and has a lower intrinsic thermo-optic coefficient; waveguide structure using negative thermo-optic coefficient As₂₅S₇₅Or As₂₀Se₈₀The material is used as a cladding material to realize the negative effective thermo-optic coefficient of the device.

The negative thermo-optic coefficient sulfur-series material cladding is used for regulating and controlling the effective thermo-optic coefficient of the device to be a negative value;

and the pulley coupling area is used for carrying out optical field coupling with the straight waveguide and the micro-ring resonant cavity through evanescent waves.

Specifically, the negative thermo-optic coefficient micro-ring resonant cavity is designed by structure, adopts a negative thermo-optic coefficient wrapping compensation scheme, presents a negative effective thermo-optic coefficient, and utilizes a negative thermo-optic coefficient sulfur material As₂₅S₇₅Or A_s20Se₈₀As a cladding, the effective thermo-optic coefficient of the micro-ring resonant cavity is regulated to a negative value, and meanwhile, a good interface combination structure of the core layer and the cladding is kept.

In the process of frequency sweeping of tunable laser, because the micro-ring resonant cavity has a negative thermo-optic coefficient, a resonant peak can spontaneously generate blue shift due to the action of thermo-optic effect in the frequency sweeping process, the drift trend of the resonant peak is shown in fig. 5, which is the drift trend of a positive thermo-optic resonant peak and a negative thermo-optic resonant peak along with the change of temperature, for a negative thermo-optic coefficient regulating device, the resonant peak spontaneously generates blue shift along with the rise of temperature, so that pump light can be quickly and stably locked in a red detuning region of the resonant cavity, therefore, the soliton frequency comb can be automatically started and stably exists, and the soliton existing region after negative thermo-optic regulation is shown in fig. 6.

While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.