PDH frequency stabilization technology-based feedforward cancellation apparatus and method for laser phase noise

Abstract

A PDH frequency stabilization technology-based feedforward cancellation apparatus (10) and method for laser phase noise, the apparatus (10) comprising: a PDH laser frequency stabilization device body (100), which is used for sampling, emitted by a laser, laser light to be subjected to frequency stabilization processing; a delay light path (200), which is connected to a beam splitter (101) of the PDH laser frequency stabilization device body (100) so as to delay the laser light except the sampled laser light; a feedforward module (400), which is connected to a low-pass filter (113) of the PDH laser frequency stabilization device body (100), and gains part of a PDH error signal output by the low-pass filter (113); and a second electro-optical modulator (300), which is separately connected to the delay light path (200) and the feedforward module (400), and uses the gained PDH error to modulate the phase of the delayed laser light, so as to cancel out the phase noise of the delayed laser light. Thus, the problem is solved that existing phase noise cancellation methods cannot provide both a good phase noise suppression effect and a relatively large optical power, or are limited by the stability of laser phase noise measurement methods.

Description

Laser phase noise feedforward elimination device and method based on PDH frequency stabilization technology

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number "202311159562.6" filed by Tsinghua University on September 8, 2023, with the invention name "Laser phase noise feedforward elimination device and method based on PDH frequency stabilization technology". Technical Field

[0003] The present application relates to the technical field of laser noise suppression, and in particular to a laser phase noise feedforward elimination device and method based on PDH frequency stabilization technology. Background Art

[0004] In experimental research in atomic, molecular, and optical physics, laser performance determines our ability to manipulate microscopic particles. With the recent advancement of quantum technology, the requirements for lasers in scientific experiments have further increased, particularly in the demand for lasers with narrow linewidth and low phase noise. However, due to the limitations of feedback bandwidth, previous laser frequency stabilization technologies can generally only suppress low-frequency noise below a few hundred kHz.

[0005] As for the method of eliminating high-frequency laser phase noise, the relevant technologies mainly include the following three methods:

[0006] The first method uses a Fabry-Perot cavity to filter the original laser and lock the main frequency of the original laser to the transmission peak of the optical cavity. Since high-frequency phase noise far from the main frequency will be reflected by the cavity, the laser passing through the cavity will have lower phase noise. However, the phase noise suppression effect of this method depends on the finesse of the Fabry-Perot cavity used. The higher the finesse, the better the effect. However, the light with low phase noise comes from the light transmitted through the cavity, and the light field intensity in the cavity increases linearly with the increase of the finesse of the cavity. In order not to damage the cavity mirror coating, a Fabry-Perot cavity with too high a finesse cannot be selected in the experiment. Therefore, this method cannot provide good phase noise suppression effect and high optical power at the same time.

[0007] The second method is to measure the phase noise of the laser by beating the original laser with its outgoing light after a period of optical fiber delay, and then use the active feedforward method to compensate the measured phase noise back to the original laser to cancel the noise.

[0008] The third method is to measure the phase noise of the laser by beating the original laser with the light transmitted through a high-precision ultrastable cavity, and then use the active feedforward method to compensate the measured phase noise back to the original laser to cancel the noise.

[0009] The second and third methods use beat frequency to measure laser phase noise. However, factors such as ambient temperature drift can cause the relative lengths of the two beat frequency optical paths to drift, resulting in unreliable measurement results. To eliminate the impact of optical path length drift on the measurement results, both solutions require an additional feedback loop. Therefore, the stability of these two methods is limited by the stability of the feedback loop.

[0010] Therefore, there is an urgent need for a method to eliminate high-frequency laser phase noise that can simultaneously provide good phase noise suppression effect and high optical power and is not limited by the stability of the laser phase noise measurement method.

[0011] Summary of the Invention

[0012] The present application provides a laser phase noise feedforward elimination device and method based on PDH (Pound-Drever-Hall) frequency stabilization technology, which greatly improves the existing PDH feedback frequency stabilization technology's ability to suppress high-frequency phase noise, and solves the problems that existing phase noise elimination methods cannot simultaneously provide good phase noise suppression effects and high optical power, or are limited by the stability of laser phase noise measurement methods.

[0013] A first embodiment of the present application provides a laser phase noise feedforward elimination device based on PDH frequency stabilization technology, comprising: a PDH laser frequency stabilization device body, used to sample laser light emitted by a laser and obtain phase noise information of the laser for frequency stabilization processing, wherein the PDH laser frequency stabilization device body comprises: a beam splitter, a Glan-Taylor prism, a first electro-optical modulator, a local oscillator, a Faraday isolator, a half-wave plate, a quarter-wave plate, a polarization beam splitter, an ultra-stable optical cavity, a phase shifter, a mixer, a photodetector, a feedback module, and a low-pass filter;

[0014] a delay optical path connected to the beam splitter to delay the laser light emitted by the laser except for the sampling portion;

[0015] a feedforward module connected to the low-pass filter to perform gain processing on a preset portion of the PDH error signal output by the low-pass filter;

[0016] A second electro-optical modulator is connected to the delay optical path and the feedforward module respectively, and uses the gained signal to phase modulate the delayed laser to offset the phase noise of the delayed laser.

[0017] Optionally, the feedforward module is specifically configured to perform gain processing on the other part of the PDH error signal based on a preset fixed gain to generate a feedforward signal, and use the feedforward signal to offset the phase noise of the laser after the delay processing.

[0018] Optionally, the preset fixed gain makes the compensation phase caused by the feedforward signal equal to the phase noise intensity of the laser output by the laser.

[0019] Optionally, the length of the delayed optical path is set based on the compensation phase caused by the feedforward signal being opposite to the phase noise phase of the laser light after the delay processing.

[0020] The second aspect of the present application provides a laser phase noise feedforward elimination method based on PDH frequency stabilization technology, comprising the following steps: sampling the laser phase noise information emitted by the laser to perform frequency stabilization processing; delaying the laser emitted by the laser except for the sampled part; performing gain processing on a preset part of the PDH error signal generated during the frequency stabilization processing; and using the gained signal to phase modulate the delayed laser to offset the phase noise of the delayed laser.

[0021] Optionally, gain processing is performed on a preset portion of the PDH error signal based on a preset fixed gain to generate a feedforward signal, and the feedforward signal is used to offset the phase noise of the laser after the delay processing.

[0022] Optionally, the preset fixed gain makes the compensation phase caused by the feedforward signal equal to the phase noise intensity of the laser output by the laser.

[0023] Optionally, the length of the delayed optical path is adjusted so that the compensation phase caused by the feedforward signal is opposite to the phase of the laser phase noise after the delay processing.

[0024] In a third aspect, an embodiment of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the laser phase noise feedforward elimination method based on PDH frequency stabilization technology as described in the above embodiment.

[0025] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the program is executed by a processor, the method for eliminating laser phase noise feedforward based on PDH frequency stabilization technology is implemented.

[0026] The laser phase noise feedforward elimination device and method based on the PDH frequency stabilization technology in the embodiment of the present application eliminates the phase noise of the laser by using the error signal of the PDH frequency stabilization technology as the feedforward signal, thereby achieving effective suppression of phase noise from hundreds of kilohertz to several megahertz, and a wide effective frequency range; it can suppress and optimize the phase noise near a specific frequency, achieving a suppression effect of nearly 40dB, and in actual measurements, by adjusting the gain and phase shift of the feedforward loop, a 42dB elimination effect can be achieved for phase noise at frequencies near 2 megahertz; there is no need to set up additional laser phase noise measurement devices and feedback devices for eliminating optical path length drift to eliminate low-frequency phase drift, thereby improving the long-term stability of the system.

[0027] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0029] FIG1 is a schematic structural diagram of a laser phase noise feedforward elimination device based on PDH frequency stabilization technology according to an embodiment of the present application, wherein the thick black solid line represents an optical signal and the thick black dashed line represents an electrical signal;

[0030] FIG2 is a comparative effect diagram of a laser phase noise feedforward elimination device based on PDH frequency stabilization technology according to an embodiment of the present application;

[0031] FIG3 is a flow chart of a method for eliminating laser phase noise feedforward based on PDH frequency stabilization technology according to an embodiment of the present application;

[0032] FIG4 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

[0033] Explanation of the accompanying symbols: 10-Laser phase noise feedforward elimination device based on PDH frequency stabilization technology, 100-PDH laser frequency stabilization device body, 101-beam splitter, 102-Glan-Taylor prism, 103-first electro-optical modulator, 104-Faraday isolator, 105-half-wave plate, 106-polarization beam splitter, 107-quarter-wave plate, 108-ultra-stable optical cavity, 109-photodetector, 110-local oscillator, 111-phase shifter, 112-mixer, 113-low-pass filter, 114-feedback module, 200-delay optical path, 300-second electro-optical modulator, 400-feedforward module, 401-memory, 402-processor and 403-communication interface. DETAILED DESCRIPTION

[0034] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0035] The following describes the laser phase noise feedforward elimination device and method based on the PDH frequency stabilization technology of the embodiment of the present application with reference to the accompanying drawings. In view of the problems mentioned in the above background technology that the existing phase noise elimination method cannot provide a good phase noise suppression effect and a large optical power at the same time, or is limited by the stability of the laser phase noise measurement method, the present application provides a laser phase noise feedforward elimination device based on the PDH frequency stabilization technology. In the device, the error signal generated by the PDH frequency stabilization technology is used to perform feedforward control through a feedforward module with a preset fixed gain, thereby achieving effective suppression of the laser high-frequency noise. Thus, the problems that the existing phase noise elimination method cannot provide a good phase noise suppression effect and a large optical power at the same time, or is limited by the stability of the laser phase noise measurement method are solved. It should be noted that when the PDH frequency stabilization technology is used to lock the main frequency of the laser to the transmission peak of a Fabry-Perot cavity with high finesse, the remaining PDH error signal reflects the real-time phase noise of the laser, wherein the output light field of a laser with phase noise that has been locked on the optical cavity can be expressed as: E0cos[ωt+φ(t)],

[0036] Where E0 is the electric field intensity amplitude, ω is the optical frequency resonating with the cavity, and φ(t) is the real-time phase noise.

[0037] After the light field is phase modulated with a frequency of Ω and an amplitude of β, it is incident on a Fabry-Perot cavity, and its form is: E inc =E0cos[ωt+βsin(Ωt)+φ(t)],

[0038] Among them, E inc is the light field incident on the cavity. The above formula can be further expanded by the first-kind Bessel function as follows:

[0039] In actual operation, the modulation frequency Ω (tens of MHz) used in the PDH frequency stabilization technology is generally much larger than the full width at half maximum of the Fabry-Perot cavity transmission peak v cav (below 100 kilohertz), that is, Ω>>v cav. In general, the amplitude of laser phase noise is much lower than the amplitude of the main frequency, that is, |φ(t)|<<1. Moreover, when the PDH frequency stabilization technology is used to lock the main frequency of the laser to the transmission peak of the Fabry-Perot cavity, the low-frequency phase noise has been suppressed by the feedback loop, so the power density spectrum peak of the phase noise generally appears in the range of several hundred kilohertz to several megahertz, which is also far beyond the half-maximum full width of the Fabry-Perot cavity transmission peak. Therefore, in addition to the main frequency of the laser, the reflectivity of the Fabry-Perot cavity for the PDH modulation sidebands and the noise light field is approximately -1. Therefore, the reflected light field is approximately:

[0040] If a photodetector is used to detect the above light field, the output signal of the detector is proportional to (E ref ) 2 Moreover, due to the limitation of detection bandwidth (hundreds of MHz), The high-frequency terms with optical frequency ω in the output signal are averaged to DC terms. Based on this, the output signal can be demodulated using a signal proportional to sin(Ωt) to obtain the PDH error signal: V PDH =CJ0(β)J1(β)sin[φ(t)],

[0041] Where C is a constant related to E0 and the internal gain of the photodetector.

[0042] When |φ(t)|<<1, sin[φ(t)]≈φ(t), then V PDH ∝φ(t). Therefore, if the PDH error signal is converted to a fixed gain By feeding forward to the phase of the original light field E0cos[ωt+φ(t)] in real time, the phase noise φ(t) of the original light field will be offset.

[0043] Therefore, in order to compensate for phase noise in real time, the present application provides a feedforward module 400 with an increased fixed gain, a delay optical path 200, and a second electro-optical modulator 300. After obtaining the PDH error signal, a portion of the PDH error signal is used for feedback control to lock the main frequency of the laser to the transmission peak of the ultra-stable optical cavity 108. The other portion of the PDH error signal is subjected to a fixed gain through the feedforward module 400 to obtain a feedforward signal, which is sent to the second electro-optical modulator 300 as a compensated feedforward signal. When the compensated feedforward signal reaches the second electro-optical modulator 300, the delay optical path 200 is used to ensure that the original light field emitted by the laser also reaches the second electro-optical modulator 300 at the same time, thereby equivalently achieving real-time correction of phase noise and eliminating laser phase noise. The specific solution is as follows.

[0044] FIG1 is a schematic structural diagram of a laser phase noise feedforward elimination device based on PDH frequency stabilization technology provided in an embodiment of the present application.

[0045] As shown in FIG1 , the laser phase noise feedforward elimination device 10 based on the PDH frequency stabilization technology includes: a PDH laser frequency stabilization device body 100 , a delay optical path 200 , a second electro-optical modulator 300 and a feedforward module 400 .

[0046] The PDH laser frequency stabilization device body 100 is used to sample the laser light emitted by the laser and obtain phase noise information of the laser light for frequency stabilization. The PDH laser frequency stabilization device body 100 includes a beam splitter 101, a Glan-Taylor prism 102, a first electro-optical modulator 103, a Faraday isolator 104, a half-wave plate 105, a polarization beam splitter 106, a quarter-wave plate 107, an ultra-stable optical cavity 108, a photodetector 109, a local oscillator 110, a phase shifter 111, a mixer 112, a low-pass filter 113, and a feedback module 114. A delay optical path 200 is connected to the beam splitter 101 to delay the laser light emitted by the laser, excluding the sampled portion. A feedforward module 400 is connected to the low-pass filter 113 to gain a predetermined portion of the PDH error signal output by the low-pass filter 113. The second electro-optical modulator 300 is connected to the delay optical path 200 and the feedforward module 400 respectively, and uses the gained signal to phase modulate the delayed laser to offset the phase noise of the delayed laser.

[0047] Furthermore, in the embodiment of the present application, the feedforward module 400 is specifically configured to perform gain processing on a preset portion of the PDH error signal based on a preset fixed gain to generate a feedforward signal, and use the feedforward signal to offset the phase noise of the laser after delay processing.

[0048] The fixed gain is preset so that the compensation phase caused by the feedforward signal is equal to the phase noise intensity of the laser after the delay processing.

[0049] Furthermore, the delayed optical path 200 in the embodiment of the present application can be an optical fiber or a free space optical path, and the length of the delayed optical path 200 is set based on the compensation phase caused by the feedforward signal and the opposite phase of the phase noise of the delayed laser to ensure that when the feedforward signal reaches the second electro-optical modulator 300, the delayed laser arrives at the same time.

[0050] In addition, to ensure that the feedforward signal and the delayed laser can arrive at the same time, those skilled in the art can also set a delayed electrical signal device between the feedforward module 400 and the second electro-optical modulator 300 according to actual conditions, and by adjusting the length of the delayed electrical signal device and the length of the delayed optical path, the delayed feedforward signal can reach the second electro-optical modulator 300 at the same time as the delayed laser.

[0051] After the feedforward signal and the delayed laser light arrive at the second electro-optical modulator 300 simultaneously, the second electro-optical modulator 300 modulates the delayed laser light using the feedforward signal, so that the feedforward signal can just offset the phase noise of the delayed laser light.

[0052] Furthermore, the working principle of the laser phase noise feedforward elimination device based on PDH frequency stabilization technology proposed in the embodiment of the present application is as follows:

[0053] The output laser of the laser is split by the beam splitter 101, and the sampling part of the laser is injected into the Glan-Taylor prism 102. The transmitted light through the Glan-Taylor prism 102 has a high degree of polarization. The laser light other than the sampling part is coupled into the delay optical path 200. The transmitted light through the Glan-Taylor prism 102 is injected into the first electro-optical modulator 103, and the local oscillator 110 provides a phase modulation with a frequency of Ω. The modulated laser is injected into the Faraday isolator 104 to prevent the reflected light from forming an external cavity and causing residual amplitude modulation. The linearly polarized light passing through the Faraday isolator 104 is adjusted in its linear deflection direction by the half-wave plate 105 so that It transmits through the polarization beam splitter 106 to the greatest extent; a quarter wave plate 107 is used to convert the linearly polarized light passing through the polarization beam splitter 106 into circularly polarized light, which is then incident on an ultra-stable optical cavity 108 with a high finesse. Because the light reflected by the cavity mirror will pass through the quarter wave plate 107 again, it will be converted into linearly polarized light again, and the polarization direction is 90 degrees different from the light first incident on the polarization beam splitter 106. Therefore, the returned reflected light is reflected by the polarization beam splitter 106 and detected by the photodetector 109; in addition to providing a modulation signal to the first electro-optical modulator 103, the local oscillator 110 also A demodulated signal is provided, which passes through a phase shifter 111 and enters a mixer 112, where it is mixed with the signal output by the photodetector 109 to obtain a PDH error signal. Subsequently, a low-pass filter 113 with a cutoff frequency lower than Ω is used to filter out high-frequency noise in the PDH error signal. The signal after passing through the low-pass filter 113 is divided into two parts, one of which enters a feedback module 114. The circuit board adds the proportional, integral and differential of the input signal to obtain an output signal, which is fed back to the external modulation port of the laser, thereby achieving PDH frequency stabilization. That is, at this time, the output frequency of the laser is locked to the ultra-stable cavity 10. 8's transmission peak; another part of the signal after passing through the low-pass filter 113 enters the feedforward module 400, which amplifies the input signal at a fixed gain and outputs a feedforward signal; the feedforward signal is input into the second electro-optical modulator 300, thereby providing phase modulation for the laser passing through the delayed optical path 200. When the gain of the feedforward module 400 is selected so that its feedforward signal intensity is exactly equal to the phase noise intensity in the laser output light, and the length of the delay optical path 200 is selected so that the phase of the feedforward signal is exactly opposite to the phase noise phase in the delayed laser, the phase noise in the output light of the second electro-optical modulator 300 is offset.

[0054] Furthermore, FIG2 shows the power spectrum (the resolution bandwidth selected during measurement is 5 kHz) of the beat signal between the output light of the laser and the reference light (the reference light is the transmitted light of the output light of the laser through a relatively high-fineness optical cavity 108) using the feedforward technology in an embodiment of the present application. It can be seen that the present application effectively suppresses the phase noise from hundreds of kilohertz to several megahertz, and achieves a 42 dB elimination effect on the phase noise at a frequency near 2 MHz.

[0055] In summary, the laser phase noise feedforward elimination device based on PDH frequency stabilization technology proposed in the embodiments of the present application has the following beneficial effects:

[0056] (1) By using the error signal of the PDH frequency stabilization technology as a feedforward signal to eliminate the phase noise of the laser, effective suppression of phase noise from hundreds of kilohertz to several megahertz is achieved, with a wide effective frequency range;

[0057] (2) It can optimize the suppression of phase noise near a specific frequency, achieving a suppression effect of nearly 40 dB or more. In actual measurements, by adjusting the gain and phase shift of the feedforward loop, it can achieve a 42 dB elimination effect on phase noise near a frequency of 2 MHz.

[0058] (3) There is no need to set up additional laser phase noise measurement devices and feedback devices to eliminate optical path length drift to eliminate low-frequency phase drift, thereby improving the long-term stability of the system.

[0059] Next, a laser phase noise feedforward elimination method based on PDH frequency stabilization technology proposed in an embodiment of the present application is described with reference to the accompanying drawings.

[0060] FIG3 is a flow chart diagram of a method for eliminating laser phase noise feedforward based on PDH frequency stabilization technology according to an embodiment of the present application.

[0061] As shown in FIG3 , the laser phase noise feedforward elimination method based on the PDH frequency stabilization technology includes the following steps:

[0062] In step S101 , the phase noise information of the laser emitted by the laser is sampled to perform frequency stabilization processing.

[0063] Specifically, the beam splitter 101 of the PDH laser frequency stabilization device body 100 splits the laser light emitted by the laser, and a sampling portion of the laser light is emitted into the PDH laser frequency stabilization device body 100 for frequency stabilization processing.

[0064] In step S102 , the laser light emitted by the laser except for the sampling portion is subjected to delay processing.

[0065] Specifically, the beam splitter 101 is connected to the delay optical path 200, and couples the laser light emitted by the laser except for the sampling part into the delay optical path for delay processing.

[0066] In step S103, gain processing is performed on a preset portion of the PDH error signal generated during the frequency stabilization process.

[0067] In step S104 , the phase of the delayed laser light is modulated using the amplified signal to cancel the phase noise of the delayed laser light.

[0068] Furthermore, in the embodiments of the present application, a predetermined portion of the PDH error signal is subjected to gain processing based on a predetermined fixed gain to generate a feedforward signal, which is used to offset the phase noise of the laser light after the delay processing. The predetermined fixed gain is such that the compensation phase caused by the feedforward signal is equal to the phase noise intensity of the laser light output by the laser.

[0069] Furthermore, in the embodiment of the present application, the length of the delayed optical path is adjusted so that the compensation phase caused by the feedforward signal is opposite to the phase noise phase of the laser after the delay processing.

[0070] It should be noted that the above explanation of the embodiment of the laser phase noise feedforward elimination device based on PDH frequency stabilization technology is also applicable to the laser phase noise feedforward elimination method based on PDH frequency stabilization technology in this embodiment, and will not be repeated here.

[0071] The laser phase noise feedforward elimination method based on the PDH frequency stabilization technology proposed in the embodiment of the present application has the following beneficial effects:

[0072] (1) By using the error signal of the PDH frequency stabilization technology as a feedforward signal to eliminate the phase noise of the laser, effective suppression of phase noise from hundreds of kilohertz to several megahertz is achieved, with a wide effective frequency range;

[0073] (2) It can suppress and optimize the phase noise near a specific frequency, achieving a suppression effect of nearly 40 dB. In actual measurements, by adjusting the gain and phase shift of the feedforward loop, it can achieve a 42 dB elimination effect on the phase noise near the frequency of 2 MHz.

[0074] (3) There is no need to set up additional laser phase noise measurement devices and feedback devices to eliminate optical path length drift to eliminate low-frequency phase drift, thereby improving the long-term stability of the system.

[0075] FIG4 is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include:

[0076] Memory 401 , processor 402 , and computer programs stored in the memory 401 and executable on the processor 402 .

[0077] When the processor 402 executes the program, the laser phase noise feedforward elimination method based on the PDH frequency stabilization technology provided in the above embodiment is implemented.

[0078] Furthermore, the electronic device further includes:

[0079] The communication interface 403 is used for communication between the memory 401 and the processor 402 .

[0080] The memory 401 is used to store computer programs that can be run on the processor 402 .

[0081] The memory 401 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0082] If memory 401, processor 402, and communication interface 403 are implemented independently, communication interface 403, memory 401, and processor 402 can be interconnected via a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. Buses can be categorized as address buses, data buses, control buses, and the like. For ease of illustration, FIG4 shows only one thick line, but this does not imply that there is only one bus or only one type of bus.

[0083] Optionally, in a specific implementation, if the memory 401 , the processor 402 and the communication interface 403 are integrated on a chip, the memory 401 , the processor 402 and the communication interface 403 can communicate with each other through an internal interface.

[0084] The processor 402 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0085] An embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the above-mentioned laser phase noise feedforward elimination method based on PDH frequency stabilization technology is implemented.

[0086] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0087] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0088] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing a custom logical function or process step, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed in a different order than shown or discussed, including performing functions in a substantially simultaneous manner or in a reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application pertain.

[0089] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or N wires (electronic devices), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program can be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing it in other suitable ways as necessary, and then storing it in a computer memory.

[0090] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiment, the N steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0091] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0092] In addition, the functional units in the various embodiments of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into a module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0093] The storage medium mentioned above may be a read-only memory, a magnetic disk, or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application. Persons skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A laser phase noise feedforward elimination device based on PDH frequency stabilization technology, characterized in that: include: The PDH laser frequency stabilization device body is used to sample the laser phase noise information emitted by the laser to perform frequency stabilization processing, wherein the PDH laser frequency stabilization device body includes: a beam splitter, a Glan-Taylor prism, a first electro-optical modulator, a local oscillator, a Faraday isolator, a half-wave plate, a quarter-wave plate, a polarization beam splitter, an ultra-stable optical cavity, a phase shifter, a mixer, a photodetector, a feedback module and a low-pass filter; A delay optical path, the delay optical path is connected to the beam splitter to delay the laser light emitted by the laser except for the sampling part; A feedforward module, the feedforward module is connected to the low-pass filter to perform gain processing on a preset part of the PDH error signal output by the low-pass filter; A second electro-optic modulator is connected to the delay optical path and the feedforward module respectively, and uses the gained signal to phase modulate the delayed laser to offset the phase noise of the delayed laser.

2. The laser phase noise feedforward elimination device based on PDH frequency stabilization technology according to claim 1 is characterized in that: The feedforward module is specifically used to perform gain processing on a preset part of the PDH error signal based on a preset fixed gain to generate a feedforward signal, and use the feedforward signal to offset the phase noise of the laser after the delay processing.

3. The laser phase noise feedforward elimination device based on PDH frequency stabilization technology according to claim 2 is characterized in that: The preset fixed gain makes the compensation phase caused by the feedforward signal equal to the phase noise intensity of the laser output by the laser.

4. The laser phase noise feedforward elimination device based on PDH frequency stabilization technology according to claim 2, characterized in that: The length of the delay optical path is set based on the compensation phase caused by the feedforward signal being opposite to the phase noise phase of the laser light after the delay processing.

5. A laser phase noise feedforward elimination method based on PDH frequency stabilization technology, characterized in that: The laser phase noise feedforward elimination device according to any one of claims 1 to 4 is used, wherein the method comprises the following steps: Sampling the laser phase noise information emitted by the laser to perform frequency stabilization processing; Delaying the laser light emitted by the laser except for the sampling part; Performing gain processing on a preset portion of a PDH error signal generated during the frequency stabilization process; The phase of the delayed laser light is modulated by using the signal after gain, so as to cancel the phase noise of the delayed laser light.

6. The laser phase noise feedforward elimination method based on PDH frequency stabilization technology according to claim 5 is characterized in that: A preset part of the PDH error signal is subjected to gain processing based on a preset fixed gain to generate a feedforward signal, and the feedforward signal is used to offset the phase noise of the laser after the delay processing.

7. The laser phase noise feedforward elimination method based on PDH frequency stabilization technology according to claim 6 is characterized in that: The preset fixed gain makes the compensation phase caused by the feedforward signal equal to the phase noise intensity of the laser output by the laser.

8. The laser phase noise feedforward elimination method based on PDH frequency stabilization technology according to claim 6 is characterized in that: The length of the delayed optical path is adjusted so that the compensation phase caused by the feedforward signal is opposite to the phase noise phase of the laser after the delay processing.

9. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the laser phase noise feedforward elimination method based on the PDH frequency stabilization technology as described in any one of claims 5 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the laser phase noise feedforward elimination method based on the PDH frequency stabilization technology as described in any one of claims 5 to 8.

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