Optical soliton generating system
阅读说明:本技术 一种光孤子产生系统 (Optical soliton generating system ) 是由 姜校顺 张孟华 白燕 肖敏 于 2020-06-15 设计创作,主要内容包括:本发明实施例公开了一种光孤子产生系统。该系统包括波长可调光源、偏振控制器、第一环行器、光纤、第一滤波器以及光学微腔;其中,光学微腔包括衬底和位于衬底一侧的支撑柱和腔体;波长可调光源用于提供泵浦光;偏振控制器用于调节泵浦光的偏振方向,以调整泵浦光与光学微腔的耦合效率;泵浦光在光学微腔中激发背向布里渊激光,背向布里渊激光在光学微腔内发生四波混频效应,产生耗散克尔孤子;第一滤波器用于滤除泵浦光和背向布里渊激光,以输出耗散克尔孤子。本发明实施例的技术方案,利用背向布里渊激光产生耗散克尔孤子,可以避免在孤子形成过程中泵浦光红失谐的热不稳定性引起复杂的调节技术,有利于实现光孤子产生系统的小型化和集成化。(The embodiment of the invention discloses an optical soliton generation system. The system comprises a wavelength-adjustable light source, a polarization controller, a first circulator, an optical fiber, a first filter and an optical microcavity; the optical microcavity comprises a substrate, a supporting column and a cavity, wherein the supporting column and the cavity are positioned on one side of the substrate; the wavelength tunable light source is used for providing pump light; the polarization controller is used for adjusting the polarization direction of the pump light so as to adjust the coupling efficiency of the pump light and the optical microcavity; the pump light excites backward Brillouin laser in the optical microcavity, the backward Brillouin laser generates a four-wave mixing effect in the optical microcavity, and dissipative Kerr solitons are generated; the first filter is used for filtering the pumping light and the backward Brillouin laser to output dissipative Kerr solitons. According to the technical scheme of the embodiment of the invention, the dissipative Kerr solitons are generated by using the backward Brillouin laser, so that a complex adjusting technology caused by thermal instability of red detuning of the pump light in the soliton forming process can be avoided, and the miniaturization and integration of an optical soliton generating system can be realized.)
1. An optical soliton generation system is characterized by comprising a wavelength-adjustable light source, a polarization controller, a first circulator, an optical fiber, a first filter and an optical microcavity;
the output end of the wavelength-tunable light source is connected with the input end of the polarization controller, the output end of the polarization controller is connected with the first end of the first circulator, the second end of the first circulator is connected with the optical fiber, and the third end of the first circulator is connected with the input end of the first filter;
the optical fiber extends from the second end of the first circulator to the optical microcavity, the optical fiber extending to the optical microcavity comprises a tapered structure, and the optical fiber is coupled with the optical microcavity through the tapered structure;
the optical microcavity comprises a substrate, a supporting column and a cavity, wherein the supporting column and the cavity are positioned on one side of the substrate;
the wavelength-adjustable light source is used for providing pump light, and the pump light is coupled into the optical fiber after passing through the polarization controller and the first circulator;
the polarization controller is used for adjusting the polarization direction of the pump light so as to adjust the coupling efficiency of the pump light and the optical microcavity;
the pump light is coupled into the optical microcavity through the conical structure, the pump light excites backward Brillouin laser in the optical microcavity, and the backward Brillouin laser generates a four-wave mixing effect in the optical microcavity to generate a dissipative Kerr soliton;
the dissipative Kerr soliton is coupled into the optical fiber, is input from the second end of the first circulator and is output from the third end of the first circulator;
the first filter is used for filtering the pumping light and the backward Brillouin laser to output the dissipative Kerr soliton.
2. The optical soliton generation system of claim 1, further comprising an optical amplifier disposed between the wavelength tunable light source and the polarization controller, the optical amplifier configured to amplify the pump light.
3. The optical soliton generation system of claim 2, wherein the optical amplifier is a semiconductor optical amplifier;
the optical soliton generation system further comprises a first collimator, an optical isolator and a second collimator;
the first collimator, the semiconductor optical amplifier, the optical isolator and the second collimator are sequentially arranged between the wavelength-tunable light source and the polarization controller along a light path;
the input end of the first collimator is coupled with the output end of the wavelength-adjustable light source and is used for collimating the pump light and then inputting the collimated pump light into the semiconductor optical amplifier;
the semiconductor optical amplifier is used for amplifying the pump light;
the optical isolator is used for enabling the amplified pump light to be transmitted in a single direction;
and the output end of the second collimator is connected with the input end of the polarization controller.
4. The optical soliton generation system of claim 2, wherein the optical amplifier is a fiber amplifier;
the wavelength-adjustable light source is connected with the input end of the optical fiber amplifier;
and the output end of the optical fiber amplifier is connected with the polarization controller.
5. The optical soliton generation system of claim 2, further comprising a second filter disposed between the optical amplifier and the polarization controller, the second filter configured to filter out spontaneously emitted light from the optical amplifier.
6. The optical soliton generation system of claim 2, further comprising an adjustable attenuator disposed between the optical amplifier and the polarization controller, the adjustable attenuator configured to adjust an output power of the amplified pump light.
7. The optical soliton generation system according to any one of claims 1 to 6, further comprising a coupler, a first photodetector, a second photodetector, an oscilloscope, and a spectrometer;
the optical fiber extending from the optical microcavity is connected with the first photodetector, the output end of the first filter is connected with the second photodetector, the first photodetector and the second photodetector are both connected with the oscilloscope, and the oscilloscope is used for outputting time domain waveforms detected by the first photodetector and the second photodetector;
the input end of the coupler is connected with the second end of the first circulator, the first output end of the coupler is connected with the input end of the first filter, the second output end of the coupler is connected with the spectrometer, and the spectrometer is used for measuring the output spectrum of the second output end of the coupler.
8. The optical soliton generation system of claim 7, wherein the first filter comprises a fiber Bragg grating configured to reflect the pump light and the back-facing Brillouin laser light and transmit the dissipative Kerr soliton;
the optical soliton generation system further comprises a second circulator, wherein a first end of the second circulator is connected with a first output end of the coupler, a second end of the second circulator is connected with an input end of the first filter, and a third end of the second circulator is connected with the spectrometer;
the spectrometer is further configured to measure an output spectrum of a third end of the second circulator.
9. The optical soliton generation system of claim 1, wherein the wavelength tunable light source is a wavelength tunable laser.
10. The optical soliton generation system of claim 1, wherein the substrate material of the optical microcavity comprises silicon and the material of the cavity comprises silicon dioxide.
Technical Field
The embodiment of the invention relates to a laser technology, in particular to an optical soliton generation system.
Background
An optical soliton is a pulse that can keep the time domain waveform and the spectrum shape unchanged during transmission. The dissipative time domain Kerr solitons based on the microcavity utilize parametric gain to compensate the loss of the microcavity and the balance of dispersion and Kerr nonlinearity, so that pulses with the pulse width of femtosecond level and the repetition frequency in the range from GHz to THz can be generated, and the pulses are represented as phase-locked optical frequency combs with equal intervals on the frequency domain. The micro-cavity soliton frequency comb has a wide spectrum and high repetition frequency, can be integrated on a chip, and has wide application in the aspects of coherent light communication, low-noise microwave sources, double-light comb spectrum, optical ranging, optical frequency synthesis, optical clocks and the like.
In order to realize the micro-cavity soliton frequency comb, the pumping laser needs to be modulated to the red detuning of a pumping cavity mode, and when the soliton is formed, the transmission spectrum of the optical comb power appears in a step shape along with the scanning of the pumping laser frequency, so that the frequency range of the pumping laser when the soliton exists is displayed. Since the thermo-optic nonlinearity of the optical microcavity can cause the cavity mode frequency red shift, the pump laser is thermally unstable in the red detuning mechanism, and the soliton state needs to be realized by using pump power modulation (power chopping), rapid adjustment of the laser frequency, or compensation of the thermal effect. The methods are complex in technology, the frequency range of the pump laser in the soliton existing region is small, extra electrical and optical components need to be introduced to adjust the power or frequency of the laser in the cavity, and the development of system miniaturization and integration is not facilitated.
Disclosure of Invention
The embodiment of the invention provides an optical soliton generation system, which utilizes blue detuned single-mode continuous pumping laser to firstly generate red detuned backward Brillouin laser in an optical microcavity and then utilizes the backward Brillouin laser to generate dissipative Kerr solitons. Because the pump laser is in a thermal stable state of blue detuning, the soliton state can be realized by directly manually adjusting the piezoelectric of the laser, the complex adjusting technology caused by the thermal instability of the red detuning of the pump laser in the soliton forming process is avoided, and the miniaturization and the integration of the optical soliton generating system are favorably realized.
The embodiment of the invention provides an optical soliton generation system, which comprises a wavelength-adjustable light source, a polarization controller, a first circulator, an optical fiber, a first filter and an optical microcavity, wherein the wavelength-adjustable light source is connected with the first circulator;
the output end of the wavelength-tunable light source is connected with the input end of the polarization controller, the output end of the polarization controller is connected with the first end of the first circulator, the second end of the first circulator is connected with the optical fiber, and the third end of the first circulator is connected with the input end of the first filter;
the optical fiber extends from the second end of the first circulator to the optical microcavity, the optical fiber extending to the optical microcavity comprises a tapered structure, and the optical fiber is coupled with the optical microcavity through the tapered structure;
the optical microcavity comprises a substrate, a supporting column and a cavity, wherein the supporting column and the cavity are positioned on one side of the substrate;
the wavelength-adjustable light source is used for providing pump light, and the pump light is coupled into the optical fiber after passing through the polarization controller and the first circulator;
the polarization controller is used for adjusting the polarization direction of the pump light so as to adjust the coupling efficiency of the pump light and the optical microcavity;
the pump light is coupled into the optical microcavity through the conical structure, the pump light excites backward Brillouin laser in the optical microcavity, and the backward Brillouin laser generates a four-wave mixing effect in the optical microcavity to generate a dissipative Kerr soliton;
the dissipative Kerr soliton is coupled into the optical fiber, is input from the second end of the first circulator and is output from the third end of the first circulator;
the first filter is used for filtering the pumping light and the backward Brillouin laser to output the dissipative Kerr soliton.
Optionally, the optical amplifier is disposed between the wavelength tunable light source and the polarization controller, and the optical amplifier is configured to amplify the pump light.
Optionally, the optical amplifier is a semiconductor optical amplifier;
the optical soliton generation system further comprises a first collimator, an optical isolator and a second collimator;
the first collimator, the semiconductor optical amplifier, the optical isolator and the second collimator are sequentially arranged between the wavelength-tunable light source and the polarization controller along a light path;
the input end of the first collimator is coupled with the output end of the wavelength-adjustable light source and is used for collimating the pump light and then inputting the collimated pump light into the semiconductor optical amplifier;
the semiconductor optical amplifier is used for amplifying the pump light;
the optical isolator is used for enabling the amplified pump light to be transmitted in a single direction;
and the output end of the second collimator is connected with the input end of the polarization controller.
Optionally, the optical amplifier is an optical fiber amplifier;
the wavelength-adjustable light source is connected with the input end of the optical fiber amplifier;
and the output end of the optical fiber amplifier is connected with the polarization controller.
Optionally, the polarization controller further comprises a second filter disposed between the optical amplifier and the polarization controller, and the second filter is configured to filter the spontaneous emission light of the optical amplifier.
Optionally, the optical amplifier further comprises an adjustable attenuator arranged between the optical amplifier and the polarization controller, and the adjustable attenuator is used for adjusting the output power of the amplified pump light.
Optionally, the system further comprises a coupler, a first photodetector, a second photodetector, an oscilloscope and a spectrometer;
the optical fiber extending from the optical microcavity is connected with the first photodetector, the output end of the first filter is connected with the second photodetector, the first photodetector and the second photodetector are both connected with the oscilloscope, and the oscilloscope is used for outputting time domain waveforms detected by the first photodetector and the second photodetector;
the input end of the coupler is connected with the second end of the first circulator, the first output end of the coupler is connected with the input end of the first filter, the second output end of the coupler is connected with the spectrometer, and the spectrometer is used for measuring the output spectrum of the second output end of the coupler.
Optionally, the first filter includes a fiber bragg grating, and the fiber bragg grating is configured to reflect the pump light and the backward brillouin laser light and transmit the dissipative kerr soliton;
the optical soliton generation system further comprises a second circulator, wherein a first end of the second circulator is connected with a first output end of the coupler, a second end of the second circulator is connected with an input end of the first filter, and a third end of the second circulator is connected with the spectrometer;
the spectrometer is further configured to measure an output spectrum of a third end of the second circulator.
Optionally, the wavelength-tunable light source is a wavelength-tunable laser.
Optionally, the substrate material of the optical microcavity includes silicon, and the material of the cavity includes silicon dioxide.
The optical soliton generation system provided by the embodiment of the invention comprises a wavelength-adjustable light source, a polarization controller, a first circulator, an optical fiber, a first filter and an optical microcavity; the optical microcavity comprises a substrate, a supporting column and a cavity, wherein the supporting column and the cavity are positioned on one side of the substrate; the pump light is provided by the wavelength-adjustable light source and is positioned in the blue detuning region of the optical microcavity, so that the optical microcavity has good thermal stability; the pump light is coupled into the optical fiber after passing through the polarization controller and the first circulator; the polarization direction of the pump light is adjusted through the polarization controller to adjust the coupling efficiency of the pump light and the optical microcavity, the pump light excites backward Brillouin laser in the optical microcavity, the mode of the backward Brillouin laser is just in an anomalous dispersion region of the optical microcavity, the backward Brillouin laser generates a four-wave mixing effect in the optical microcavity, and a dissipative Kerr soliton is generated; the dissipative Kerr soliton is coupled into the optical fiber, is input from the second end of the first circulator and is output from the third end of the first circulator; the first filter filters the pumping light and the backward Brillouin laser, and the output of the dissipative Kerr soliton is achieved. The optical soliton generation system provided by the embodiment can avoid a complex adjusting technology caused by thermal instability of pump laser red detuning in the soliton forming process, and is beneficial to realizing miniaturization and integration of the optical soliton generation system.
Drawings
Fig. 1 is a schematic structural diagram of an optical soliton generation system according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the optical soliton generation principle provided by the embodiment of the present invention;
FIG. 3 is a schematic structural diagram of an optical microcavity provided in accordance with an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of another optical soliton generation system provided by an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of another optical soliton generation system provided by an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of another optical soliton generation system provided by an embodiment of the present invention;
FIG. 7 is a schematic structural diagram of another optical soliton generation system provided by an embodiment of the present invention;
FIG. 8 is a schematic structural diagram of another optical soliton generation system provided by an embodiment of the present invention;
FIG. 9 is a schematic diagram of waveforms collected by an oscilloscope in accordance with an embodiment of the present invention;
FIG. 10 is a schematic spectral diagram of optical solitons collected by a spectrometer in an embodiment of the present invention;
fig. 11 is a schematic diagram of the spectra of the pump light collected by the spectrometer and the back brillouin laser in the embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. It should be noted that the terms "upper", "lower", "left", "right", and the like used in the description of the embodiments of the present invention are used in the angle shown in the drawings, and should not be construed as limiting the embodiments of the present invention. In addition, in this context, it is also to be understood that when an element is referred to as being "on" or "under" another element, it can be directly formed on "or" under "the other element or be indirectly formed on" or "under" the other element through an intermediate element. The terms "first," "second," and the like, are used for descriptive purposes only and not for purposes of limitation, and do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Currently, soliton frequency combing has been implemented in optical microcavities of materials such as magnesium fluoride, silicon oxide, silicon nitride, and the like. The silicon oxide micro-cavity integrated on the chip has an ultrahigh quality factor, and can realize a soliton frequency comb with detectable repetition frequency. Since the silicon oxide material has a large thermo-optic nonlinear coefficient, it has been realized to utilize power modulation (power chopping), single sideband modulation, and a method of compensating the thermal effect using auxiliary light to tune the pump laser to red detune to generate optical solitons. In the power modulation method, the acousto-optic modulator is required to be used for quickly reducing the power of the pumping light, so that the intracavity heat effect and the Kerr nonlinear effect are weakened, the cavity mode is blue-shifted, the detuning of the pumping light relative to the cavity mode reaches a red detuning area, the pumping power is quickly improved, and the detuning range of solitons is expanded (the higher the pumping power is, the larger the detuning range of the solitons is); in the single-sideband modulation method, a single-sideband modulator is required to adjust the frequency scanning speed of the pump laser to enable the pump laser to reach a red detuning state, and a PDH (Pound-Drever-Hall) locking technology is used for stabilizing the detuning of the pump laser; the thermal compensation method needs to utilize additional auxiliary laser to be coupled into the cavity, and compensates cavity mode frequency change caused by laser power change in the cavity when the pump laser is adjusted from blue detuning to red detuning, so that the optical soliton state can be stably realized by adjusting the laser frequency. The methods all need to introduce additional electrical and optical components, the frequency range of the pump laser in which solitons exist is relatively narrow, and the frequency adjustment method of the pump laser is complex, so that the miniaturization and integration development of optical devices are not facilitated.
To solve the above problem, fig. 1 is a schematic structural diagram of an optical soliton generation system according to an embodiment of the present invention. Referring to fig. 1, the optical soliton generation system provided in this embodiment includes a wavelength tunable light source 10, a polarization controller 20, a first circulator 30, an optical fiber 40, a first filter 50, and an optical microcavity 60; the output end of the wavelength tunable light source 10 is connected to the input end of the polarization controller 20, the output end of the polarization controller 20 is connected to the first end of the first circulator 30, the second end of the first circulator 30 is connected to the optical fiber 40, and the third end of the first circulator 30 is connected to the input end of the first filter 50; the optical fiber 40 extends from the second end of the first circulator 30 to the optical microcavity 60, the optical fiber 40 extending to the optical microcavity 60 including a tapered structure (not shown in fig. 1), the optical fiber 40 being coupled with the optical microcavity 60 through the tapered structure; wherein, the optical microcavity 60 includes a substrate and a supporting pillar and a cavity on one side of the substrate; the wavelength tunable light source 10 is used for providing pump light, and the pump light is coupled into the optical fiber 40 after passing through the polarization controller 20 and the first circulator 30; the polarization controller 20 is configured to adjust the polarization direction of the pump light to adjust the coupling efficiency of the pump light and the optical microcavity 60; the pump light is coupled into the optical microcavity 60 through the conical structure, the pump light excites backward Brillouin laser in the optical microcavity 60, the backward Brillouin laser generates a four-wave mixing effect in the optical microcavity 60, and dissipative Kerr solitons are generated; the dissipative kerr solitons are coupled into the optical fiber 40, input from the second end of the first circulator 30 and output from the third end of the first circulator 30; the first filter 60 is used to filter out the pump light and the backward brillouin laser light to output a dissipative kerr soliton.
The wavelength tunable
For example, fig. 2 is a schematic diagram illustrating a principle of optical soliton generation according to an embodiment of the present invention. Referring to fig. 2(a), the pump light p is coupled into the
Referring to FIG. 2(b), ω1、ω2、ω3And ω4Respectively representing the frequency of the pumping cavity mode, the frequency of the Brillouin cavity mode, the Brillouin cavity mode frequency shift caused by the Kerr self-phase modulation of the Brillouin laser, and the central frequency of the Brillouin gain, omegapIn the blue detuning region, omega, for pumping the laser frequencysAt the brillouin laser frequency, in the red detuned region, Ω denotes the frequency of the acoustic mode. The detuning of the Brillouin laser can be obtained by a coupling mode equation
Wherein gamma ismLine width, γ, representing an acoustic mode2The line width, g, of the Brillouin cavity mode2Denotes the Kerr nonlinear coefficient, asIndicating the brillouin laser amplitude and omega the acoustic mode frequency. The first term represents the detuning change of the brillouin laser caused by kerr self-phase modulation of the brillouin laser, wherein the kerr self-phase modulation can cause red shift of a brillouin cavity mode and equivalently can cause red shift of the frequency of the brillouin laser, so that the generated brillouin laser is in red detuning; the second term represents the detuning change of the brillouin laser caused by the mismatch of the brillouin cavity mode frequency, the pumping laser frequency and the acoustic mode, and when the frequency difference of the pumping laser and the brillouin cavity mode is smaller than the acoustic mode frequency, the generated brillouin laser is also in red detuning. Due to gamma in the microcavitym>>γsThe change in the pump laser frequency is much greater than the resulting change in the brillouin detuning. In an experiment, when the pump laser frequency is adjusted to change the detuning of the brillouin laser, a larger pump laser frequency range is provided corresponding to the brillouin laser detuning range with solitons, that is, the soliton step is longer when the pump laser frequency is scanned.According to the technical scheme of the embodiment, the pump light is provided by the wavelength-adjustable light source and is positioned in the blue detuning region of the optical microcavity, so that the optical microcavity has good thermal stability; the pump light is coupled into the optical fiber after passing through the polarization controller and the first circulator; the polarization direction of the pump light is adjusted through the polarization controller to adjust the coupling efficiency of the pump light and the optical microcavity, the pump light excites backward Brillouin laser in the optical microcavity, the mode of the backward Brillouin laser is just in an anomalous dispersion region of the optical microcavity, the backward Brillouin laser generates a four-wave mixing effect in the optical microcavity, and a dissipative Kerr soliton is generated; the dissipative Kerr soliton is coupled into the optical fiber, is input from the second end of the first circulator and is output from the third end of the first circulator; the first filter filters the pumping light and the backward Brillouin laser, and the output of the dissipative Kerr soliton is achieved. The optical soliton generation system provided by the embodiment can avoid a complex adjusting technology caused by thermal instability of pump laser red detuning in the soliton forming process, and is beneficial to realizing miniaturization and integration of the optical soliton generation system.
On the basis of the above technical solution, optionally, the wavelength-tunable light source is a wavelength-tunable laser.
It can be understood that, because the laser has many advantages such as high brightness, good directivity, good monochromaticity, etc., in practical implementation, the wavelength tunable light source may be a wavelength tunable laser and output through an optical fiber to generate high-power pump light.
Optionally, the substrate material of the optical microcavity comprises silicon, and the material of the cavity comprises silicon dioxide.
Fig. 3 is a schematic structural diagram of an optical microcavity according to an embodiment of the present invention. Referring to fig. 3, the optical microcavity is a microcavity including a substrate 61 and a support post 62 and a microdisk 63 located on one side of the substrate. Both the substrate 61 and the support posts 62 may be selected from silicon and the microdisk cavities 63 may be selected from silicon dioxide. In this embodiment, the microdisk cavity 63 is a circular truncated cone, and the circular truncated cone is coupled to the optical fiber through a tapered structure of the optical fiber.
Fig. 4 is a schematic structural diagram of another optical soliton generation system according to an embodiment of the present invention. Referring to fig. 4, optionally, the optical soliton generation system provided in this embodiment further includes an
It is understood that, in implementation, the power of the pump light output by the wavelength tunable
Fig. 5 is a schematic structural diagram of another optical soliton generation system according to an embodiment of the present invention. Referring to fig. 5, the
It can be understood that the semiconductor optical amplifier is difficult to integrate with the optical fiber, the wavelength-
Optionally, the optical amplifier is an optical fiber amplifier; the wavelength-adjustable light source is connected with the input end of the optical fiber amplifier; the output end of the optical fiber amplifier is connected with the polarization controller.
It can be understood that the optical amplifier may also be an optical fiber amplifier, and the optical path is transmitted only in the optical fiber, so as to reduce the coupling difficulty of the optical path. In other embodiments, other types of optical amplifiers may also be selected, which is not limited in this embodiment of the present invention.
Optionally, with continuing reference to fig. 4, the optical soliton generation system further includes a
Optionally, with continued reference to fig. 4, the optical soliton generation system further includes an
It is understood that the
Fig. 6 is a schematic structural diagram of another optical soliton generation system according to an embodiment of the present invention. Referring to fig. 6, optionally, the optical soliton generation system provided in this embodiment further includes a
It can be understood that in order to verify whether the optical soliton generation system provided by the embodiment of the present invention generates dissipative kerr solitons, a test needs to be performed, and whether optical solitons are generated can be determined by observing the time domain waveform of the
Fig. 7 is a schematic structural diagram of another optical soliton generation system according to an embodiment of the present invention. Referring to fig. 7, optionally, the
It should be noted that the foregoing are only exemplary embodiments of the present invention, and in practical implementation, a combination of optical devices may be selected according to practical requirements to meet practical application requirements. Fig. 8 is a schematic structural diagram of another optical soliton generation system according to an embodiment of the present invention, and the present embodiment provides a specific example based on the above embodiment. Referring to fig. 8, the optical soliton generation system includes a wavelength tunable
In this embodiment, a silicon oxide microdisk cavity with a diameter of 6mm and a thickness of 8 μm is used, and the intrinsic Q values of the pumping mode and the Brillouin mode are respectively 4.81 × 107,8.44×107. The generation process of the optical solitons is as follows:
firstly, running pump light at low power, and scanning laser frequency at the speed of 349 MHz/ms; then two space modes with the frequency interval of about 10.8GHz are found on a forward power transmission spectrum of the oscilloscope, and then the laser power is increased and far exceeds the threshold of Brillouin laser; then continuously adjusting the coupling positions of the VOA, the FPC and the optical microcavity and the optical fiber conical structure to adjust the power and the coupling state of the pump light until an optical frequency comb is observed on a spectrometer and a step-shaped transmission spectrum is observed on an oscilloscope for monitoring a reverse transmission spectrum at the same time, which indicates that an optical soliton is generated; and stopping scanning the laser frequency, and adjusting the frequency to the region where the solitons are generated by manually adjusting the piezoelectric of the laser because the pumping laser frequency region corresponding to the solitons is wider.
Wherein the frequency interval between the pump light frequency and the backward brillouin laser is about 10.8GHz, fig. 9 is a schematic diagram of a waveform collected by an oscilloscope according to an embodiment of the present invention, wherein the pump light transmission spectrum is the forward optical power detected by the first photodetector 91(PD1), and the optical comb transmission spectrum is the backward optical power detected by the second photodetector 92(PD2), and is used for searching for a soliton step. It can be seen from fig. 9 that the optical frequency comb transmission spectrum has a significant step shape, which means the generation of optical solitons, and the frequency range of the pump laser light is close to 200MHz when the solitons exist.
Fig. 10 is a schematic diagram showing a spectrum of optical solitons collected by a spectrometer according to an embodiment of the present invention. Wherein (a), (b) are multiple solitons, and (c) are single solitons. By fitting the spectral shape of the single soliton to assume sech2Form, according to the theoryThe description of the single soliton above confirms that the soliton is single soliton, and the repetition frequency of the soliton is 11.14 GHz. Fig. 11 is a schematic diagram showing spectrums of pump light and backward brillouin laser light collected by a spectrometer in an embodiment of the present invention, so that it can be known that an optical soliton provided in this embodiment is generated by the brillouin laser light.
In the optical soliton generation system provided by this embodiment, a beam of continuous single-frequency pump light is coupled into an on-chip silicon oxide microdisk cavity, and optical solitons are generated in the same cavity by using brillouin laser generated by the optical soliton; and the wide step generated by the Brillouin laser in the same cavity can be used for directly and manually adjusting the laser to generate the optical solitons, a complex frequency or power adjusting method is not needed, and the development of system miniaturization and integration is facilitated.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
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