All-fiber quantum frequency-selective laser and implementation method thereof

Abstract

The present invention discloses an all-fiber quantum frequency-selective laser and its implementation method. The laser includes: an all-fiber quantum frequency-selective laser module, an all-fiber frequency stabilization module and a phase-locked loop module. The all-fiber frequency stabilization module locks the laser output by the all-fiber quantum frequency-selective laser module to the corresponding atomic transition spectrum line, so that the locking reference of the laser frequency can be traced back to the source; when the phase-locked loop module is used for the dual-frequency output of the all-fiber quantum frequency-selective laser module, the difference between the two laser mode frequencies is compared with the microwave reference signal, and the error signal obtained by the comparison is input to the servo controller, and then the feedback signal is output to control the piezoelectric ceramic and then control the cavity length of the laser resonant cavity, so as to realize the locking of the difference between the two laser mode frequencies with the reference of the ground state hyperfine energy level interval. The present invention designs an all-fiber quantum frequency-selective laser, the diode is packaged as an optical fiber output, and all the components required for the formation of quantum frequency-selective laser oscillation are connected through optical fibers to generate an all-fiber quantum frequency-selective laser.

Description

Technical Field

[0001] The present invention relates to the field of lasers, and in particular to an all-fiber quantum frequency-selective laser and a realization method thereof. Background Art

[0002] Lasers are widely used in people's production and life. Lasers with ultra-high stability, narrow line width, output wavelengths that automatically correspond to atomic transition spectral lines, and especially lasers whose output frequencies are immune to external temperature and current fluctuations are of great significance to scientific research, such as quantum precision measurement, cold atomic physics, quantum optics, precision spectroscopy, aerospace, timekeeping, and precision guidance. Traditional quantum frequency-selective lasers, such as Faraday lasers and Focke lasers, all use atomic filters such as Faraday anomalous dispersion atomic filters or Focke anomalous dispersion atomic filters as frequency-selective devices for external cavity semiconductor lasers under free space light to achieve laser output. The above-mentioned free-space quantum frequency-selective lasers have the characteristics of output wavelengths that automatically correspond to atomic spectral lines and output frequencies that are robust to changes in diode temperature and drive current. They have extremely high reliability and environmental adaptability and can be widely used in basic scientific research and high-end instruments, equipment and other systems.

[0003] However, the quantum frequency-selective lasers reported so far are all under free-space light. Free-space quantum frequency-selective lasers are sensitive to optical angles. A very small angle deflection during the installation process will cause the output optical power to drop rapidly, thereby increasing the difficulty of installation. The length of the laser resonant cavity is directly related to the overall volume of the laser, which makes it subject to relatively large restrictions, resulting in cavity mode spacing (free spectral range) in the order of hundreds of MHz or even GHz, and laser mode hopping will inevitably occur, thereby introducing large frequency changes, making its long-term frequency stability unable to meet the requirements of some applications. Increasing the length of the resonant cavity and reducing the free spectral range can effectively reduce the impact of mode hopping on long-term frequency stability. At the same time, under self-use space light, due to mechanical stability issues, the length of the laser resonant cavity will inevitably jitter, which will also affect the long-term stability of the laser output frequency. In addition, the formation of laser oscillation by free-space quantum frequency-selective lasers is extremely demanding. The emitted light must return to the light source of the laser diode along the original path to the greatest extent possible to meet the starting conditions. At the same time, the laser output is sensitive to mechanical vibrations, environmental changes and other factors that may affect the optical path. Even if the above-mentioned problems are improved to the greatest extent through the design of the mechanical structure, it will have a certain negative impact on the volume, weight and other aspects, thereby limiting its application scenarios to a certain extent.

[0004] In summary, an ultra-high stability, small size, high stability, and portable all-fiber quantum frequency-selective laser is a difficult problem that needs to be solved urgently. Summary of the invention

[0005] The present invention provides an all-fiber quantum frequency-selective laser and its realization method. The present invention takes quantum frequency-selective laser generation as the basic principle and combines the precision spectroscopy frequency stabilization technology to realize the generation of ultra-high stability, small volume, high stability and portable all-fiber quantum frequency-selective laser. See the following description for details:

[0006] An all-fiber quantum frequency-selective laser, comprising: an all-fiber quantum frequency-selective laser module, an all-fiber frequency stabilization module and a phase-locked loop module.

[0007] The all-fiber quantum frequency-selective laser module uses an all-fiber atomic filter to achieve mode selection and output single-frequency or dual-frequency laser;

[0008] The all-fiber frequency stabilization module locks the laser output by the all-fiber quantum frequency-selective laser module to the corresponding atomic transition spectrum line, so that the locking reference of the laser frequency can be traced back to the source;

[0009] When the phase-locked loop module is used for dual-frequency output of the all-fiber quantum frequency-selective laser module, after one of the frequencies is locked by the all-fiber frequency stabilization module, the difference between the two laser mode frequencies is compared with the microwave reference signal, and the error signal obtained by the comparison is input into the servo controller, and then a feedback signal is output to control the piezoelectric ceramic and then the cavity length of the laser resonant cavity for feedback, so as to achieve the locking of the difference between the two laser mode frequencies with reference to the ground state hyperfine energy level interval; thus, after cooperating with the all-fiber frequency stabilization module to stabilize one of the dual frequencies, the phase-locked loop module is used to stabilize the frequency difference between the two frequencies, so as to achieve full traceability locking of the two frequencies.

[0010] Among them, the all-fiber quantum frequency-selective laser module includes: a laser diode for providing collimated optical fiber output with gain, and the laser diode includes: 420nm band, 421nm band, 455nm band, 459nm band, 766nm band, 770nm band, 780nm band, 795nm band, 852nm band, 894nm band, 1367nm band, 1470nm band, and 1529nm band.

[0011] Furthermore, the fiber quantum frequency-selective laser module includes: an all-fiber atomic filter for laser mode selection, and the all-fiber atomic filter includes: a first fiber polarization beam splitter, a fiber atomic gas chamber, a second fiber polarization beam splitter, and a permanent magnet.

[0012] The first fiber polarization beam splitter matches the second fiber polarization beam splitter in the laser resonant cavity, and the fiber atomic gas chamber is fixed integrally to the permanent magnet. The anti-reflection coated fiber output laser diode is used as the gain medium, and the collimated fiber output method is adopted. The broadband fluorescence emitted is adjusted so that the fluorescence polarization direction coincides with the optical axis of the first fiber polarization beam splitter, and then passes through the first fiber polarization beam splitter, and then passes through the fiber atomic gas chamber surrounded by the permanent magnet.

[0013] The optical fiber atomic gas chamber contains different single atoms or mixed atoms or injected buffer gas, and the single atoms include potassium atoms, sodium atoms, strontium atoms, cesium atoms, and rubidium atoms; the injected buffer gas includes helium and xenon.

[0014] The all-fiber atomic filter comprises: a Faraday anomalous dispersion atomic filter and a Focke anomalous dispersion atomic filter; the magnetic field direction of the permanent magnet coincides with or is perpendicular to the optical axis, corresponding to the Faraday anomalous dispersion atomic filter and the Focke anomalous dispersion atomic filter respectively.

[0015] Furthermore, the all-fiber quantum frequency-selective laser module includes: a fiber reflection cavity mirror, and the fiber reflection cavity mirror is: a fiber plane reflection cavity mirror or a fiber angle pyramid reflection cavity mirror.

[0016] The all-fiber frequency stabilization module includes: a fiber isolator, a third fiber polarization beam splitter, a fiber electro-optic modulator, a fiber atomic gas chamber, a fourth fiber polarization beam splitter, a first signal generator, a first fiber detector, a mixer, and a first servo controller;

[0017] After the laser is output by the all-fiber quantum frequency-selective laser module, it passes through the optical fiber isolator and is incident on the third optical fiber polarization beam splitter to be divided into two beams of light, one of which is connected to the fourth optical fiber polarization beam splitter and is divided into two beams again; of the two beams of light divided by the fourth optical fiber polarization beam splitter, one passes through the optical fiber atomic gas chamber and is connected to the fifth optical fiber polarization beam splitter; the other is connected to the optical fiber electro-optic modulator, passes through the optical fiber electro-optic modulator and is connected to the fifth optical fiber polarization beam splitter, and then returns to the optical fiber atomic gas chamber to form a loop; the fifth optical fiber polarization beam splitter is connected to the first optical fiber detector, the first signal generator is connected to the optical fiber electro-optic modulator to provide a modulation function for it, the first optical fiber detector detection is connected to the mixer, and the first signal generator is also connected to the mixer to provide a demodulation function to obtain an error signal, the error signal is connected to the first servo controller by the mixer and transmitted to the servo controller, and the servo controller acts on the laser diode and PZT according to the feedback generated by the error signal to form feedback.

[0018] Furthermore, the all-fiber frequency stabilization module adopts an all-fiber form, which is a frequency stabilization method of an all-fiber quantum frequency-selective laser.

[0019] The phase-locked loop module includes: a sixth optical fiber polarization splitter, a second optical fiber photoelectric detector, a phase detector, a second signal generator, a second servo controller and a high-precision reference atomic clock;

[0020] The third optical fiber polarization beam splitter is connected to the sixth optical fiber polarization splitter to split the light into two beams and introduce them into the phase-locked loop module, one of which is connected to the second optical fiber detector to obtain the frequency difference of the dual-frequency mode, and the second optical fiber detector is connected to the phase detector; the high-precision atomic clock is connected to the second signal generator to provide a reference signal, and the second signal generator is connected to the phase detector to provide the required microwave frequency reference; the phase detector is connected to the second servo controller to input the generated error signal to the second servo controller, and the second servo controller is connected to the PZT to feed back the feedback signal to the PZT to achieve locking.

[0021] A method for realizing an all-fiber quantum frequency-selective laser, the method comprising:

[0022] The anti-reflection film-coated laser diode adopts the collimated fiber output mode, connected to the first fiber polarization beam splitter, the incident light enters the fiber atomic gas chamber, enters the second fiber polarization beam splitter, and finally enters the fiber reflection cavity mirror, so that the incident light is reflected back to the anti-reflection film-coated laser diode, and after multiple oscillations in the cavity, it forms a laser and is output by the second fiber polarization beam splitter;

[0023] Place a fiber optic isolator. The output power after passing through the fiber optic isolator is the largest. Connect the third fiber optic polarization beam splitter to split it into two paths, one of which is used for output and the other is used for laser frequency stabilization.

[0024] The third optical fiber polarization beam splitter is connected to the fourth optical fiber polarization beam splitter to be divided into two paths, namely, detection light and pump light, and the light intensity ratio of the detection light and the pump light is determined by the splitting ratio of the fourth optical fiber polarization beam splitter; the detection light is connected to the optical fiber atomic gas chamber for quantum reference through the optical fiber, and then connected to the fifth optical fiber polarization beam splitter; the pump light is connected to the optical fiber electro-optic modulator, and then the optical fiber electro-optic modulator is connected to the fifth optical fiber polarization beam splitter, so as to realize the combination of the pump light and the detection light and generate the first error signal of the modulation transfer spectrum;

[0025] The fifth optical fiber polarization beam splitter is connected to the first optical fiber detector, and the pump light is sent to the first optical fiber detector for detection to obtain a second error signal generated according to the modulation transfer spectrum; the second error signal is input to the first servo controller to generate a PID feedback control signal to the anti-reflection film-coated optical fiber output laser diode and piezoelectric ceramics, and feedback is performed through current regulation and resonant cavity length adjustment to obtain an all-fiber quantum frequency-selective laser.

[0026] The first error signal of the modulation transfer spectrum is generated as follows:

[0027] The first signal generator provides a modulation signal to the optical fiber electro-optic modulator and a demodulation signal to the mixer to obtain a phase-modulated pump light, which interacts with the unmodulated detection light in the optical fiber atomic gas chamber for quantum reference and the atoms, and transfers the modulation of the pump light to the detection light through the atoms, so that the detection light has the characteristics of phase modulation;

[0028] The ±1st order sideband intensity of the detection light is related to the detuning amount of the light relative to the atomic center transition frequency, and the first error signal of the modulation transfer spectrum is obtained through corresponding demodulation.

[0029] The beneficial effects of the technical solution provided by the present invention are:

[0030] 1. The present invention designs an all-fiber atomic filter based on a fiber gas chamber, including a fiber Faraday anomalous dispersion atomic filter and a fiber Focke anomalous dispersion atomic filter, which can meet the requirements of quantum frequency selective laser to form laser oscillation;

[0031] 2. The present invention designs an all-fiber quantum frequency-selective laser, in which the diode is packaged as an optical fiber output, and all components required for the formation of quantum frequency-selective laser oscillation are connected through optical fibers to generate an all-fiber quantum frequency-selective laser;

[0032] 3. The present invention designs an all-fiber precision spectrum laser frequency locking technology to lock the output laser frequency of the all-fiber quantum frequency-selective laser, thereby realizing an ultra-high stability, small size, high stability, and portable all-fiber quantum frequency-selective laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 An optical path diagram of an all-fiber quantum frequency-selective laser module and an all-fiber frequency stabilization module in an all-fiber quantum frequency-selective laser and an implementation method thereof;

[0034] Figure 2 The present invention is a connection diagram of an all-fiber quantum frequency-selective laser module, an all-fiber frequency stabilization module and a phase-locked loop module in an all-fiber quantum frequency-selective laser and an implementation method thereof.

[0035] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0036] 1: Anti-reflection coated fiber output laser diode; 2: First fiber polarization beam splitter;

[0037] 3: Fiber optic atomic gas chamber for optical filter; 4: Permanent magnet;

[0038] 5: piezoelectric ceramic (PZT); 6: second optical fiber polarization beam splitter;

[0039] 7: Fiber optic reflector cavity mirror; 8: Fiber optic isolator;

[0040] 9: third optical fiber polarization beam splitter; 10: fourth optical fiber polarization beam splitter;

[0041] 11: Fiber optic atomic gas cell for quantum reference; 12: Fiber optic electro-optic modulator;

[0042] 13: fifth optical fiber polarization beam splitter; 14: first optical fiber detector;

[0043] 15: mixer; 16: first signal generator;

[0044] 17: a first servo controller; 18: a sixth optical fiber polarization beam splitter;

[0045] 19: second optical fiber detector; 20: phase detector;

[0046] 21: Second signal generator; 22: High-precision reference atomic clock;

[0047] 23: second servo controller; 110: detection light;

[0048] 111: Pump light. DETAILED DESCRIPTION

[0049] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention are described in further detail below.

[0050] Example 1

[0051] See also Figure 1 and Figure 2 An all-fiber quantum frequency-selective laser designed in an embodiment of the present invention includes: an all-fiber quantum frequency-selective laser module, an all-fiber frequency stabilization module and a phase-locked loop module.

[0052] 1. All-fiber quantum frequency-selective laser module

[0053] The core of this module is the all-fiber atomic filter, which mainly plays the role of laser mode selection, including atomic filters based on the principles of Faraday anomalous dispersion and Focke anomalous dispersion. The all-fiber atomic filter is mainly composed of a first fiber polarization beam splitter 2, a fiber atomic gas chamber 3, a second fiber polarization beam splitter 6, and a permanent magnet 4. The first fiber polarization beam splitter 2 and the second fiber polarization beam splitter 6 are required to reasonably match the polarization direction of the light passing through the laser resonant cavity to ensure the filtering effect of the atomic filter. The fiber atomic gas chamber 3 and the permanent magnet 4 are fixed in an integrated manner. The anti-reflection film-coated fiber output laser diode 1 is used as the gain medium, and the collimated fiber output method is adopted. The broadband fluorescence it emits passes through the first fiber polarization beam splitter 2 after being adjusted so that the fluorescence polarization direction coincides with the optical axis of the first fiber polarization beam splitter 2, and then passes through the fiber atomic gas chamber 3 surrounded by the permanent magnet 4. It should be noted that the direction of the magnetic field provided by the permanent magnet 4 can coincide with the optical axis or be perpendicular to the optical axis, corresponding to the Faraday anomalous dispersion atomic filter and the Focke anomalous dispersion atomic filter respectively.

[0054] Since the first optical fiber polarization beam splitter 2 acts as a polarizer, the light incident to the optical fiber atom gas chamber 3 becomes linearly polarized light, which can be divided into left-handed and right-handed circularly polarized light. Due to the presence of an external magnetic field, the energy levels of atoms in the optical fiber atom gas chamber 3 will undergo Zeeman splitting, so that left-handed and right-handed circularly polarized light correspond to different transition frequencies, resulting in corresponding splitting of the absorption and dispersion curves of the two. The dispersion curve is directly related to the refractive index of light. The splitting of the dispersion curve makes left-handed and right-handed circularly polarized light have different refractive indices, that is, when passing through the same path, the two have different phase changes, resulting in the deflection of the polarization direction of the linear polarized light, that is, the occurrence of optical rotation effect. The optical rotation effect is directly related to the incident light intensity, the magnitude of the external magnetic field, the length of the optical fiber atom gas chamber 3, and the atomic density (atomic gas chamber temperature) in the optical fiber atom gas chamber 3. When the incident light intensity is determined, the angle of optical rotation is determined by the atomic number density (gas chamber temperature) in the optical fiber atom gas chamber 3, the strength of the external magnetic field, and the length of the optical fiber atom gas chamber 3. In the all-fiber atomic filter, the polarization directions of the light transmitted by the first optical fiber polarization beam splitter 2 and the second optical fiber polarization beam splitter 6 are perpendicular to each other, so only light with a polarization direction rotation angle close to 90° can pass through the all-fiber atomic filter, be incident on the optical fiber reflection cavity mirror 7, and then return to the anti-reflection film-coated laser diode 1, thereby forming a laser oscillation output. The above optical rotation effect can only occur with light close to the atomic transition frequency, so the output frequency of the quantum frequency selective laser is always near the quantum transition frequency, and has the property of being immune to changes in the diode drive current and operating temperature.

[0055] The all-fiber atomic filter can not only select a specific frequency to pass through, forming laser oscillation and producing single-longitudinal mode laser output; at the same time, it can also select two specific frequencies of laser to pass through, forming laser oscillation and producing single-cavity dual-longitudinal mode laser output. The single and dual longitudinal mode outputs of the laser can be adjusted accordingly according to the actual application.

[0056] After the laser output is formed, the output laser frequency can be locked through precision spectral locking technology, such as modulation transfer spectrum, saturation absorption spectrum, polarization polarization spectrum, etc., so that it is locked to the corresponding atomic transition spectrum line, and an absolute frequency reference is obtained to achieve traceability; Pound-Drever-Hall and precision spectroscopy technology can also be used to achieve the short-term frequency stability and long-term frequency stability of the laser to meet application requirements. The embodiment of the present invention is through theoretical analysis, combined with experimental data summary and analysis, and through matching the atomic number density in the gas chamber, axial uniform magnetic field intensity, gas chamber temperature, and gas chamber length and other condition parameters, a single-frequency or dual-frequency fiber atomic filter is designed, that is, the filter can have a single-frequency or dual-frequency transmission spectrum according to actual application needs, thereby achieving single-frequency or dual-frequency laser output.

[0057] The optical fiber atomic chamber contains different atoms or mixed atoms. Other similar methods should be within the spirit and principle of the present invention, and any modifications, equivalent substitutions, improvements, etc. should be included in the protection scope of the present invention.

[0058] 2. All-fiber frequency stabilization module

[0059] Among them, the all-fiber frequency stabilization module is mainly composed of a third fiber polarization beam splitter 9, a fiber electro-optic modulator 12, a fiber atomic gas chamber 11, a fourth fiber polarization beam splitter 10, a first signal generator 16, a first fiber detector 14, a mixer 15, and a first servo controller 17. The all-fiber frequency stabilization module can be used to lock the laser output by the all-fiber quantum frequency selective laser module to the corresponding atomic transition spectrum, so that the locking reference of the laser frequency can be truly traced. In particular, the all-fiber frequency stabilization module can be specifically a mainstream laser frequency stabilization method such as modulation transfer spectrum, saturated absorption spectrum frequency stabilization, and dual-color laser frequency stabilization.

[0060] Among them, the all-fiber frequency stabilization module adopts an all-fiber form, which is a frequency stabilization method for all-fiber quantum frequency selective lasers. Modulation transfer spectrum, saturation absorption spectrum, polarization polarization spectrum, frequency modulation spectrum, circular dichroism frequency stabilization, etc. should all be within the protection scope of the embodiments of the present invention. Other methods such as all-fiber PDH cavity and other methods for stabilizing the frequency of all-fiber quantum frequency selective lasers should also be within the protection scope of the embodiments of the present invention.

[0061] 3. Phase-locked loop module

[0062] Among them, the phase-locked loop module is mainly used for the dual-frequency output of the laser. By comparing the difference between the two laser mode frequencies with the microwave reference signal, the error signal obtained by comparison is input into the second servo controller 23, and then the feedback signal is output to control the piezoelectric ceramic (PZT) and then control the cavity length of the laser resonant cavity to achieve the locking of the ground state hyperfine energy level interval, so that both laser frequencies can be traced back to the quantum reference. The phase-locked loop module is composed of a second fiber photodetector 6, a phase detector 20, a second servo controller 23 and a high-precision reference atomic clock 22. The frequency of the dual-frequency laser output by the all-fiber quantum frequency selective laser has two degrees of freedom, namely the jitter of its own absolute frequency and the jitter of the absolute frequency difference of the two lasers. By locking the laser of any frequency in the dual frequency to the corresponding atomic transition spectrum and locking the frequency difference between the dual-frequency lasers, the absolute frequencies of the dual-frequency lasers can be kept traceable.

[0063] Therefore, when the all-fiber quantum frequency-selective laser in the embodiment of the present invention is in a dual-frequency output state, it has extremely strong anti-interference ability and environmental adaptability; in the dual-frequency output state, the output laser has a common resonant cavity, so the dual-frequency laser generated in this way has the characteristics of ultra-high stability and narrow linewidth. In particular, the phase-locked loop module can also be replaced with other modules with similar locking functions, all of which belong to the scope of the embodiment of the present invention.

[0064] In summary, the embodiments of the present invention design an all-fiber atomic filter based on a fiber gas chamber, including a fiber Faraday anomalous dispersion atomic filter and a fiber Focke anomalous dispersion atomic filter, etc., which can meet the requirements of quantum frequency selective laser to form laser oscillation.

[0065] Example 2

[0066] The embodiment of the present invention introduces a method for realizing an all-fiber quantum frequency-selective laser. Taking all-fiber quantum frequency selection as the basic principle, the oscillation output of the laser is realized through quantum frequency selection means such as all-fiber Faraday atomic filter and all-fiber Focke atomic filter. Compared with the quantum frequency-selective laser in the free-space light state, the all-fiber method is adopted, and the laser structure is more stable, the volume is more compact, the frequency stability is higher, and the portability is stronger, which can greatly increase its anti-interference ability and environmental adaptability. The frequency stabilization module in the embodiment of the present invention is explained by taking the modulation transfer spectrum frequency stabilization as an example, and the method includes the following steps:

[0067] 101: The anti-reflection film-coated laser diode adopts the optical fiber output mode after collimation, and the spot size remains constant within the propagation range of 5 meters. When the optical fiber is coupled to the output, the fluorescence polarization direction coincides with the optical axis of the output optical fiber, thereby ensuring the maximum energy output; connected to the first optical fiber polarization beam splitter 2, the incident light enters the optical fiber atomic gas chamber 3, and then enters the second optical fiber polarization beam splitter 6, and finally enters the optical fiber reflection cavity mirror 7, so that the incident light is reflected back to the anti-reflection film-coated laser diode 1, and after multiple oscillations in the cavity, the laser is formed and output by the second optical fiber polarization beam splitter 6;

[0068] Among them, the piezoelectric ceramic (PZT) 5 is used to adjust the length of the laser resonant cavity. When connected, the optical fiber and the piezoelectric ceramic 5 are bonded by glue. When the length of the piezoelectric ceramic (PZT) 5 changes, the length of the optical fiber in the resonant cavity can be driven to change at the same time, thereby realizing the adjustment of the length of the resonant cavity.

[0069] 102: After the laser oscillation is formed, the optical fiber isolator 8 is placed, and the output power after passing through the optical fiber isolator 8 needs to be maximum, and then the third optical fiber polarization beam splitter 9 is connected to be divided into two paths, one of which is used for output and the other is used for laser frequency stabilization;

[0070] 103: Connect the third optical fiber polarization beam splitter 9 to the fourth optical fiber polarization beam splitter 10 to split into two paths, namely, the detection light 110 and the pump light 111. The light intensity ratio of the detection light 110 and the pump light 111 can be determined by the splitting ratio of the fourth optical fiber polarization beam splitter 10; the detection light 110 is connected to the optical fiber atomic gas chamber 11 for quantum reference through the optical fiber, and then connected to the fifth optical fiber polarization beam splitter 13; the pump light 111 is connected to the optical fiber electro-optic modulator 12 to provide a modulation signal, and then the optical fiber electro-optic modulator 12 is connected to the fifth optical fiber polarization beam splitter 13 to realize the combination of the pump light and the detection light, thereby generating a first error signal of the modulation transfer spectrum;

[0071] Among them, in order to obtain the error signal of the first modulation transfer spectrum, the first signal generator 16 is required to provide a modulation signal to the optical fiber electro-optic modulator 12, and provide a demodulation signal to the mixer 15. The phase-modulated pump light 111 is obtained, and the unmodulated detection light 110 acts together with the atoms in the optical fiber atomic gas chamber 11 for quantum reference. Due to four-wave mixing, the modulation of the pump light can be transferred to the detection light through the atoms, so that the detection light also has the characteristics of phase modulation. The modulation sideband of the detection light, that is, the intensity of the ±1-order sideband is related to the detuning amount of the light relative to the atomic center transition frequency, which is an obvious absorption linear relationship. Therefore, the modulation sideband intensity is the maximum when the light resonates with the atom. Then, through corresponding demodulation, the first error signal of the modulation transfer spectrum can be obtained.

[0072] 104: Connect the fifth optical fiber polarization beam splitter 13 to the first optical fiber detector 14, send the pump light 110 to the first optical fiber detector 14 for detection, and obtain a second error signal generated according to the modulation transfer spectrum; input the second error signal to the first servo controller 17, generate a PID feedback control signal to the anti-reflection film-coated optical fiber output laser diode 1 and the piezoelectric ceramic (PZT) 5, and feedback is performed through current regulation and resonant cavity length regulation, so as to obtain an ultra-high stability, small size, high stability, and portable all-fiber quantum frequency-selective laser.

[0073] In summary, the embodiments of the present invention take all-fiber quantum frequency selection as the basic principle to achieve ultra-high stability, small size, high stability, and portable all-fiber quantum frequency selective laser.

[0074] Example 3

[0075] As mentioned above, the all-fiber quantum frequency-selective laser can output single longitudinal mode laser or dual longitudinal mode laser according to the needs. Figure 2 The specific implementation method of the dual longitudinal mode output in the implementation method of an all-fiber quantum frequency-selective laser provided in Example 2 is described in detail:

[0076] Step 201: Figure 2 As shown, the optical path is built according to the optical path diagram and the optical path connection of the corresponding phase-locked loop module is carried out, the dual longitudinal mode output mode, and the precise spectrum stabilization frequency locks one of the longitudinal modes to the quantum transition spectrum line;

[0077] Step 202: When the all-fiber quantum frequency selective laser is in a dual longitudinal mode output mode, the third optical fiber polarization beam splitter 9 outputs to the sixth optical fiber polarization beam splitter 18, and is divided into two paths by the sixth optical fiber polarization beam splitter 18, one of which is output and the other is detected by the second optical fiber detector 19. The detected optical signal is the difference between the two laser mode frequencies. The second optical fiber detector 19 converts the detected optical signal into an electrical signal and inputs it into the phase detector 20. The microwave reference signal generated by the second signal generator 21 with the high-precision reference atomic clock 22 as the output reference will also be input into the phase detector 20, and then the error signal generated by the phase detector 20 will be connected as an input to the second servo controller 23. The output signal generated by the second servo controller 23 is used to feedback control the piezoelectric ceramic (PZT) 5, thereby controlling the resonant cavity length, ensuring the ultra-high stability and low noise of the difference between the two laser mode frequencies, so that both longitudinal modes can be locked to the corresponding quantum reference.

[0078] In summary, the embodiment of the present invention takes the all-fiber quantum frequency-selective filter as the basic principle, and combines the anti-reflection film-coated fiber output laser diode, fiber reflection cavity mirror, etc. to realize an ultra-high stability, small size, high stability, and portable all-fiber quantum frequency-selective laser. Compared with free-space light, the quantum frequency-selective laser realized by the all-fiber structure greatly reduces the complexity of the device and greatly improves the stability. At the same time, the output laser frequency is locked to the atomic transition spectrum in an all-fiber manner, and the performance such as laser frequency stability will be maintained at an extremely high level, and the short-term stability will reach the -14th power level; it will play an active role in basic scientific research such as quantum precision measurement, atomic physics, quantum optics, and practical engineering applications such as aerospace.

[0079] Unless otherwise specified, the models of the components in the embodiments of the present invention are not limited, and any device that can perform the above functions may be used.

[0080] Those skilled in the art will appreciate that the accompanying drawing is only a schematic diagram of a preferred embodiment, and the serial numbers of the embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An all-fiber quantum frequency-selective laser, characterized in that: The laser includes: an all-fiber quantum frequency-selective laser module, an all-fiber frequency-stabilizing module and a phase-locked loop module. The all-fiber quantum frequency-selective laser module uses an all-fiber atomic filter to achieve mode selection and output single-frequency or dual-frequency laser; The all-fiber frequency stabilization module locks the laser output by the all-fiber quantum frequency-selective laser module to the corresponding atomic transition spectrum line, so that the locking reference of the laser frequency can be traced back to the source; When the phase-locked loop module is used for dual-frequency output of the all-fiber quantum frequency-selective laser module, after one of the frequencies is locked by the all-fiber frequency stabilization module, the difference between the two laser mode frequencies is compared with the microwave reference signal, and the error signal obtained by the comparison is input into the servo controller, and then a feedback signal is output to control the piezoelectric ceramic and then the cavity length of the laser resonant cavity for feedback, so as to achieve the locking of the difference between the two laser mode frequencies with the interval of the ground state hyperfine energy level as a reference; thus, after cooperating with the all-fiber frequency stabilization module to stabilize one of the dual frequencies, the phase-locked loop module is used to stabilize the frequency difference between the two frequencies, so as to achieve full traceability locking of the two frequencies; The all-fiber atomic filter comprises: a first fiber polarization beam splitter, a fiber atomic gas chamber, a second fiber polarization beam splitter, and a permanent magnet. The first fiber polarization beam splitter matches the second fiber polarization beam splitter in the laser resonant cavity, and the fiber atomic gas chamber is fixed integrally to the permanent magnet. The anti-reflection coated fiber output laser diode is used as the gain medium, and the collimated fiber output method is adopted. The broadband fluorescence emitted is adjusted so that the fluorescence polarization direction coincides with the optical axis of the first fiber polarization beam splitter, and then passes through the first fiber polarization beam splitter, and then passes through the fiber atomic gas chamber surrounded by the permanent magnet.

2. The all-fiber quantum frequency-selective laser according to claim 1, characterized in that: The all-fiber quantum frequency-selective laser module includes: a laser diode for providing collimated optical fiber output with gain, and the laser diode includes: 420nm band, 421nm band, 455nm band, 459nm band, 766nm band, 770nm band, 780nm band, 795nm band, 852nm band, 894nm band, 1367nm band, 1470nm band, and 1529nm band.

3. The all-fiber quantum frequency-selective laser according to claim 1, characterized in that: The optical fiber quantum frequency-selective laser module comprises: an all-optical fiber atomic filter for laser mode selection.

4. The all-fiber quantum frequency-selective laser according to claim 3, characterized in that: The optical fiber atomic gas chamber contains different single atoms or mixed atoms or injected buffer gas, wherein the single atoms include potassium atoms, sodium atoms, strontium atoms, cesium atoms, and rubidium atoms; the injected buffer gas includes helium and xenon; The all-fiber atomic filter comprises: a Faraday anomalous dispersion atomic filter and a Focke anomalous dispersion atomic filter; the magnetic field direction of the permanent magnet coincides with or is perpendicular to the optical axis, corresponding to the Faraday anomalous dispersion atomic filter and the Focke anomalous dispersion atomic filter respectively.

5. The all-fiber quantum frequency-selective laser according to claim 1, characterized in that: The all-fiber quantum frequency-selective laser module comprises: a fiber reflection cavity mirror, and the fiber reflection cavity mirror is: a fiber plane reflection cavity mirror or a fiber angle pyramid reflection cavity mirror.

6. The all-fiber quantum frequency-selective laser according to claim 1, characterized in that: The all-fiber frequency stabilization module includes: a fiber isolator, a third fiber polarization beam splitter, a fiber electro-optic modulator, a fiber atomic gas chamber, a fourth fiber polarization beam splitter, a first signal generator, a first fiber detector, a mixer, and a first servo controller; After the laser is output by the all-fiber quantum frequency-selective laser module, it passes through the optical fiber isolator and is incident on the third optical fiber polarization beam splitter to be divided into two beams of light, one of which is connected to the fourth optical fiber polarization beam splitter and is divided into two beams again; of the two beams of light divided by the fourth optical fiber polarization beam splitter, one passes through the optical fiber atomic gas chamber and is connected to the fifth optical fiber polarization beam splitter; the other is connected to the optical fiber electro-optic modulator, passes through the optical fiber electro-optic modulator and is connected to the fifth optical fiber polarization beam splitter, and then returns to the optical fiber atomic gas chamber to form a loop; the fifth optical fiber polarization beam splitter is connected to the first optical fiber detector, the first signal generator is connected to the optical fiber electro-optic modulator to provide a modulation function for it, the first optical fiber detector detection is connected to the mixer, and the first signal generator is also connected to the mixer to provide a demodulation function to obtain an error signal, the error signal is connected to the first servo controller by the mixer and transmitted to the servo controller, and the servo controller acts on the laser diode and PZT according to the feedback generated by the error signal to form feedback.

7. The all-fiber quantum frequency-selective laser according to claim 6, characterized in that: The all-fiber frequency stabilization module adopts an all-fiber form, which is a frequency stabilization method of an all-fiber quantum frequency-selective laser.

8. The all-fiber quantum frequency-selective laser according to claim 6, characterized in that: The phase-locked loop module includes: a sixth optical fiber polarization splitter, a second optical fiber photoelectric detector, a phase detector, a second signal generator, a second servo controller and a high-precision reference atomic clock; The third optical fiber polarization beam splitter is connected to the sixth optical fiber polarization splitter to split the light into two beams and introduce them into the phase-locked loop module, one of which is connected to the second optical fiber detector to obtain the frequency difference of the dual-frequency mode, and the second optical fiber detector is connected to the phase detector; the high-precision atomic clock is connected to the second signal generator to provide a reference signal, and the second signal generator is connected to the phase detector to provide the required microwave frequency reference; the phase detector is connected to the second servo controller to input the generated error signal to the second servo controller, and the second servo controller is connected to the PZT to feed back the feedback signal to the PZT to achieve locking.

9. A method for realizing an all-fiber quantum frequency-selective laser, characterized in that: The method comprises: The anti-reflection film-coated laser diode adopts the collimated fiber output mode, connected to the first fiber polarization beam splitter, the incident light enters the fiber atomic gas chamber, enters the second fiber polarization beam splitter, and finally enters the fiber reflection cavity mirror, so that the incident light is reflected back to the anti-reflection film-coated laser diode, and after multiple oscillations in the cavity, it forms a laser and is output by the second fiber polarization beam splitter; Place a fiber optic isolator. The output power after passing through the fiber optic isolator is the largest. Connect the third fiber optic polarization beam splitter to split it into two paths, one of which is used for output and the other is used for laser frequency stabilization. The third optical fiber polarization beam splitter is connected to the fourth optical fiber polarization beam splitter to be divided into two paths, namely, detection light and pump light, and the light intensity ratio of the detection light and the pump light is determined by the splitting ratio of the fourth optical fiber polarization beam splitter; the detection light is connected to the optical fiber atomic gas chamber for quantum reference through the optical fiber, and then connected to the fifth optical fiber polarization beam splitter; the pump light is connected to the optical fiber electro-optic modulator, and then the optical fiber electro-optic modulator is connected to the fifth optical fiber polarization beam splitter, so as to realize the combination of the pump light and the detection light and generate the first error signal of the modulation transfer spectrum; The fifth optical fiber polarization beam splitter is connected to the first optical fiber detector, and the pump light is sent to the first optical fiber detector for detection to obtain a second error signal generated according to the modulation transfer spectrum; the second error signal is input to the first servo controller to generate a PID feedback control signal to the anti-reflection film-coated optical fiber output laser diode and piezoelectric ceramics, and feedback is performed through current regulation and resonant cavity length adjustment to obtain an all-fiber quantum frequency-selective laser.

10. The method for realizing an all-fiber quantum frequency-selective laser according to claim 9, characterized in that: The first error signal of the modulation transfer spectrum is generated as follows: The first signal generator provides a modulation signal to the optical fiber electro-optic modulator and a demodulation signal to the mixer to obtain a phase-modulated pump light, which interacts with the unmodulated detection light in the optical fiber atomic gas chamber for quantum reference and the atoms, and transfers the modulation of the pump light to the detection light through the atoms, so that the detection light has the characteristics of phase modulation; The ±1st order sideband intensity of the detection light is related to the detuning amount of the light relative to the atomic center transition frequency, and the first error signal of the modulation transfer spectrum is obtained through corresponding demodulation.

Images