General-purpose integrated all-fiber optical control system

Abstract

A general integrated all-fiber optical control system comprises a reference light laser, a cooling light laser, a probe light laser, a laser beam combining module, a laser beam splitting module, a frequency control module, an optical switch module and a power stabilization module. The lasers output single-frequency laser beams in fiber mode. The laser beam combining module integrates light beams of different frequencies into the same fiber. The laser beam splitting module outputs laser power to different fibers according to the required ratio. The frequency control module adjusts the frequency and power of the laser beams. The optical switch module realizes the required optical switch control. The power stabilization module adjusts the output power in real time to keep it consistent with the reference power. The present application realizes the time sequence control of multiple laser beams based on fiber devices, and has the characteristics of miniaturization, easy integration, easy transportation and stable performance, and is particularly suitable for cold atom experiments based on ground laboratory or special environment (space station, shipborne, satellite borne).

Description

Technical Field

[0001] This invention belongs to the field of laser cooling atomic technology, specifically relating to a general-purpose integrated all-fiber optical control system. Background Technology

[0002] With the development of novel laser-based atomic cooling techniques in recent decades, such as magneto-optical traps, polarization gradient cooling, evaporative cooling, two-stage cross-cooling, and Delta-kick cooling, we can reduce the temperature of atoms from room temperature to the pK level. During evaporative cooling, the atomic temperature continuously decreases. When the temperature of the atomic sample falls below a threshold, the sample enters a quantum degenerate state, ultimately described by quantum mechanics. Once in the degenerate region, bosons follow Bose-Einstein statistics, meaning all atoms occupy the same quantum state and are described by the same wave function; fermions obey Fermi-Dirac statistics, making it impossible for two identical atoms to be in the same quantum state. The quantum degenerate gas experimental platform based on bosons and fermions provides a broader platform for studying many-body interactions, quantum simulation, quantum precision measurement, and Feshbach resonance modulation.

[0003] Capturing and cooling atoms at room temperature, as well as detecting atoms, requires the simultaneous combining, splitting, power control, and frequency adjustment of multiple laser beams of various frequencies. Typical laboratory setups employ a series of free-space optical elements fixed to an optical platform to perform these functions simultaneously. However, this fixed-platform free-space optical approach places higher demands on the stability of both the platform and the optical elements, requiring regular maintenance of the unstable optical path. Furthermore, it necessitates a large area to house and fix all the optical elements, making it inconvenient to transport. Optimizing the optical path of these free-space optical elements is also quite complex. With the increasing application of laser-cooled atom technology in special environments in recent years, developing a highly integrated, stable, and easily transportable optical system will greatly expand the research scope and application value of cold atom technology. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] The purpose of this invention is to provide an all-fiber optical system suitable for conducting cold atom experiments in ground-based laboratories or special environments (space stations, shipborne, spaceborne). This system meets the requirements for multi-beam, multi-frequency laser splitting, combining, power adjustment, frequency adjustment, and switching control in atomic manipulation processes. The entire control system is based on fiber optic devices and features miniaturization, ease of integration, ease of transportation, and stable performance.

[0006] (II) Technical Solution

[0007] This invention provides an all-fiber optical control system suitable for the field of cold atom, comprising: a reference laser, a cooling laser, a probe laser, a laser beam combiner module, a laser beam splitter module, a frequency control module, an optical switch module, and a power stabilization module.

[0008] The reference laser is a frequency-stabilized laser whose laser frequency is locked to a specified transition energy level of a selected atom; the laser is output via fiber optic; the optical signal of this laser, after passing through a frequency modulation module, outputs an optical signal with a frequency that matches the frequency of the repumped light required for the experiment.

[0009] The cooled laser is a frequency-stabilized laser whose frequency can be locked to a reference laser via a phase-locked loop (PLL) module. The frequency of the laser's output light signal is consistent with the frequency of the cooling light required for the experiment. The laser's output frequency can be shifted relative to the reference laser via the PLL module to meet the timing requirements for manipulating the selected atoms. The laser uses fiber optic output.

[0010] The probe laser is a frequency-stabilized laser whose frequency is locked to that of the reference laser via a phase-locked loop (PLL) module. The PLL module can also be used to shift the laser's frequency relative to the reference laser, ensuring that the laser's output frequency meets the timing requirements for manipulating the selected atoms. After passing through a frequency modulation module, the output light signal's frequency matches the frequency of the probe light required for the experiment. The probe laser uses fiber optic output.

[0011] The optical fiber output method can be optical fiber output or free space beam coupling into the optical fiber and finally output from the optical fiber.

[0012] Laser beam combining modules can integrate beams of different frequencies into a single fiber output; different frequencies of light can be beams with different functions used to manipulate the same atom or isotope (cooling light and re-pumping light); different frequencies of light can also be light with the same function used to manipulate different atoms or isotopes, such as controlling... 87 Rb and 40 Cooling light, re-pumping light, or probe light for K atoms.

[0013] Laser beam combining modules can output laser power to different optical fibers according to the required ratio. There are two types of laser beam combining modules: one with only one output and the other with two outputs. The power ratio of different frequency optical signals in each output and the power ratio of the same frequency optical signals in the two outputs depend on the beam combining ratio of the laser beam combining module for the input laser.

[0014] The center frequency of the frequency control module is such that the output frequency of the laser can be adjusted to the frequency required to manipulate atoms; this module must have the function of adjusting the power of the optical signal; and the response time of this module as an optical switch must meet the timing requirements.

[0015] Optical switch modules can achieve switching control that meets timing requirements.

[0016] The power stabilization module compares the real-time acquired output optical signal with a reference signal and uses algorithms to control and adjust the output optical signal to maintain consistency with the reference signal. The power stabilization module primarily aims to achieve stable MOT and molasses atomic signals. The power of the six cooling beams used to achieve 3D-MOT is acquired in real-time and converted into voltage signals. For each pair of opposing cooling beams, one output is used as a reference signal and differentially compared with the voltage converted from the opposing optical power. The differential signal is then processed by a PID controller and fed back as an error signal to the power control module, ultimately ensuring that the optical signal output from the fiber optic cable maintains real-time consistency with the opposing optical power.

[0017] The first cooling laser, the first reference laser, and the first probe laser are laser sources that control the same isotope; the second cooling laser, the second reference laser, and the second probe laser are used to control another isotope.

[0018] A general-purpose integrated all-fiber optical control system can simultaneously manipulate two types of atoms or two isotopes of the same atom. However, in actual use, the number of isotopes or atoms manipulated can be adjusted according to the experimental requirements by adjusting the optical components in the control system to ultimately meet the experimental needs.

[0019] (III) Beneficial Effects

[0020] The present invention has the following beneficial effects;

[0021] 1) Easy to integrate and transport, featuring miniaturization and stable performance;

[0022] 2) This invention is entirely based on fiber optic devices, requires no frequent maintenance, is easy to engineer and commercialize, and provides a solution for conducting cold atom experiments in laboratory or special environments (space station, shipborne, spaceborne).

[0023] 3) Applicable to cold atom systems that manipulate the number of atoms or isotopes greater than or equal to one, greatly simplifying the optical control system for cold atom experiments based on multiple atoms or isotopes;

[0024] 4) This invention has universal applicability in the field of laser cooling of atoms and is applicable to physical experiments involving laser cooling of atoms such as lithium, sodium, rubidium, potassium, and cesium. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the integrated all-fiber optical control system according to an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram illustrating the usage method of an integrated all-fiber optical control system applicable to the field of laser-cooled atoms, as described in an embodiment of the present invention.

[0027] Figure 3 As used in the embodiments of the present invention 87 A schematic diagram of the D2 spectral lines of Rb atoms and the laser transition frequencies.

[0028] Figure 4 As used in the embodiments of the present invention 40 Schematic diagram of K atom D2 spectral lines and laser transition frequencies.

[0029] Figure 5 This is a schematic diagram of the algorithm for the power stabilization module in an embodiment of the present invention.

[0030] In the picture:

[0031] 1-First cooled optical laser; 2-First optical switch module; 3-Second cooled optical laser; 4-Second optical switch module; 5-First beam combiner module; 6-Third optical switch module; 7-First beam splitter module; 8-Second beam splitter module; 9-Second beam combiner module; 10-Third beam splitter module; 11-Fourth beam splitter module; 12-Fifth beam splitter module; 13-Sixth beam splitter module; 14-First power control module; 15-Second power control module; 16-Seventh beam splitter module; 17-Third power control module; 18-Third beam combiner module; 19-Fourth beam combiner module; 20-First reference laser; 21-First frequency Control module; 22-Eighth beam splitter module; 23-Second reference laser; 24-Second frequency control module; 25-Ninth beam splitter module; 26-Fourth optical switch module; 27-Fifth optical switch module; 28-Fifth beam combiner module; 29-Sixth optical switch module; 30-Seventh optical switch module; 31-Sixth beam combiner module; 32-First probe laser; 33-Third frequency control module; 34-Second probe laser; 35-Fourth frequency control module; 36-Seventh beam combiner module; 37-Tenth beam splitter module; 38-Eighth optical switch module; 39-Ninth optical switch module; 40-Tenth optical switch module. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments and the accompanying drawings. It should be noted that in the accompanying drawings or description, the same modules use the same graphics.

[0033] The realization of Bose-Fermi mixed gases provides an ideal experimental platform for studying high-temperature superconductivity and the strong interaction. Since the D2 lines of Rb and K atoms differ by only 13 nm, many general-purpose optical elements can be used for this purpose. 87 Rb、 40 The Bose-Fermi mixed gas experimental platform implemented by K greatly simplifies the experimental equipment. In this embodiment, an all-fiber optical control system is provided for preparing Bose (… 87 Rb)-Fermi 40 K) degenerate gases, but the present invention is not limited thereto and should not limit the scope of protection of the present invention.

[0034] The application scope of the all-fiber optical control system applicable to the field of cold atoms in this invention application should not be limited by the type or number of atoms used. Modifications to the all-fiber optical control system made for practical applications, such as changes to the parameters, quantity, or location of the beam splitting module, beam combining module, frequency control module, switching module, and power stabilization module to change the type or number of manipulated atoms, should be considered within the scope of protection of this invention if they are similar or identical to this invention in terms of system structure and composition.

[0035] like Figure 1 As shown, an all-fiber optical control system suitable for the field of cold atoms includes: a first cooling laser 1, a second cooling laser 3, a first reference laser 20, a second reference laser 23, a first probe laser 32, and a second probe laser 34, which serve as the input optical signals of the all-fiber optical control system.

[0036] The frequency of the first cooling laser 1 is locked to the first reference laser 20 via a phase-locked loop, relative to... 87 RbD2 line|5 2 S 1 / 2 F = 2 > → |5 2 P 3 / 2 ,F'=3>Red detuning 3Γ(Γ=6.06MHz is 87 The natural linewidth of the Rb D2 line is determined, and the frequency detuning can be adjusted from 0 to -1 GHz during the experiment; the frequency of the second cooling laser 3 is locked to the second reference laser 23 via a phase-locked loop, relative to... 40 K D2 line|4 2 S 1 / 2 F = 9 / 2 > → |4 2 P 3 / 2 F' = 11 / 2 > Red detuning 3Γ (Γ = 6.035MHz) 40The natural linewidth of the K D2 line was measured, and the frequency detuning was adjustable from 0 to -1 GHz during the experiment. The two cooled lasers ultimately output via fiber optics.

[0037] The optical signal from the first cooling laser 1 passes through the first optical switch 2, and the optical signal from the second cooling laser 3 passes through the second optical switch 4. After passing through the first beam combining module 5, the beam is split to provide the cooling light required for the cooling atomic process.

[0038] The first beam combining module 5 has two outputs, namely the first output and the second output, each of which contains... 87 Rb、 40 The cooling light of K. The first output passes through the third optical switch 6 and is input to the first beam splitter module 7, where it is further split into two paths: the third and the fourth. The third path is used as the push light and outputs from the all-fiber optic platform. The fourth optical signal enters the second beam splitter module 8 and is split into two paths: the fifth and the sixth. The fifth path is used as 2D-cooling light and outputs from the all-fiber optic platform. The sixth path, together with the repumping light from the reference laser, enters the second beam combiner module 9 and is used as 2D-cooling / repumping light and outputs from the all-fiber optic platform. The second optical signal enters the third beam splitter module 10 and is split into two paths: the seventh and the eighth. The seventh optical signal passes through the fourth beam splitter module 11 and is split into two paths: the ninth and the tenth. The ninth optical signal passes through the fifth beam splitter module 12 and is split into two paths: the eleventh and the twelfth. The eleventh path is used as 3D-cooling light-1 and outputs from the all-fiber optic platform. The twelfth optical signal enters the first power stabilization module 14 and is used as 3D-cooling light-2 and outputs from the all-fiber optic platform. The tenth optical signal enters the sixth beam splitter module 13 and is split into two paths, namely the thirteenth and fourteenth paths. The thirteenth path is output from the all-fiber optical platform as 3D-cooling light-3, and the fourteenth path is output from the all-fiber optical platform as 3D-cooling light-4 after entering the second power stabilization module 15. The eighth optical signal enters the seventh beam splitter module 16 and is split into two paths, namely the fifteenth and sixteenth paths. The fifteenth path optical signal and the repumped light from the reference laser enter the third beam combiner module 18 and are combined to form 3D-cooling / repumped light-1, which is output from the all-fiber optical platform. The sixteenth path optical signal enters the third power stabilization module 17 and the repumped light from the reference laser enter the fourth beam combiner module 19 and are combined to form 3D-cooling / repumped light-2, which is output from the all-fiber optical platform.

[0039] The frequency of the first reference laser 20 is locked at... 87 Rb D2 line|5 2 S 1 / 2 F = 1 > → |5 2 P 3 / 2 ,F'=0> and |5 2P 3 / 2 The cross line, F'=1>, indicates that the laser's final output is via fiber optic output. The optical signal from the first reference laser 20 is shifted by 193MHz by the first frequency control module 21 and then... 87 Rb D2|5 2 S 1 / 2 F = 1 > → |5 2 P 3 / 2 F' = 2> resonance, used to provide cooling 87 The heavy pump light required for Rb atomic processes.

[0040] The frequency of the second reference laser 23 is locked at... 39 K D2 line|4 2 S 1 / 2 F = 2 > → |4 2 P 3 / 2 F' = 3>, the final output of the laser is via fiber optic output. The optical signal from the second reference laser 23 is shifted by 432MHz by the second frequency control module 24 and then... 40 K D2|4 2 S 1 / 2 F = 7 / 4 > → |4 2 P 3 / 2 F' = 11 / 2 > resonance, used to provide cooling 40 The heavy pump light required for K atomic processes.

[0041] The optical signal output from the first frequency modulation module 21 enters the eighth beam splitter module 22 and is split into two outputs, namely the seventeenth and eighteenth channels. The optical signal output from the second frequency modulation module 24 enters the ninth beam splitter module 25 and is split into two outputs, namely the nineteenth and twentieth channels. The seventeenth optical signal passes through the fourth optical switch 26 and the nineteenth optical signal passes through the sixth optical switch 29 to be combined into the fifth beam combiner module 28 and finally into the second beam combiner module 9 to provide a re-pumping optical signal for 2D-MOT. The eighteenth optical signal passes through the fifth optical switch 27 and the twentieth optical signal passes through the seventh optical switch 30 to be combined into the sixth beam combiner module 31, finally outputting two optical signals, which are combined with the third beam combiner module 18 and the fourth beam combiner module 19 respectively to serve as 3D-MOT cooling / re-pumping light-1 and 3D-MOT cooling / re-pumping light-2, which are output from the all-fiber optical platform.

[0042] The frequency of the first probe laser 32 is locked at... 87 Rb D2 line|5 2 S 1 / 2 F = 2 > → |5 2 P 3 / 2The laser frequency can be adjusted according to experimental requirements, and the laser linewidth is 1 MHz. The second probe laser 34 is frequency-locked at [a specific frequency]. 40 K D2 line|4 2 S 1 / 2 F = 9 / 2 > → |4 2 P 3 / 2 The laser's frequency can be adjusted according to experimental requirements, and its linewidth is 1MHz. The optical signals output from the first probe laser 32 and the second probe laser 34 are shifted by 80MHz by the third frequency adjustment module 33 and the fourth frequency adjustment module 35, respectively, to provide the probe light required for the atomic process. The two probe signals enter the seventh beam combining module 36 and output two optical signals, namely the twenty-first and twenty-second signals. The twenty-first signal passes through the tenth beam combining module 37 and outputs two optical signals, namely the twenty-third and twenty-fourth signals. The twenty-third signal passes through the eighth optical switch 38 as probe light-1 and is output from the all-fiber optic platform. The twenty-fourth signal passes through the ninth optical switch 39 as probe light-2 and is output from the all-fiber optic platform. The twenty-second signal passes through the tenth optical switch 40 as probe light-3 and is output from the all-fiber optic platform.

[0043] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of this invention.

Claims

1. A general-purpose integrated all-fiber optical control system, characterized in that, include: The reference laser is a frequency-stabilized laser whose laser frequency is locked to a specified transition energy level of a selected atom. The optical signal output by the fiber optic method, after passing through the frequency modulation module, has a frequency that is consistent with the frequency of the repumped light required for the experiment. The cooled optical laser is a frequency-stabilized laser whose laser frequency is locked to the reference laser via a phase-locked loop module. The frequency of the optical signal output by the optical fiber is consistent with the frequency of the cooling light required for the experiment. The probe laser is a frequency-stabilized laser whose frequency is locked to the reference laser via a phase-locked loop module. The frequency of the optical signal output via fiber optic means is consistent with the frequency required for the experiment. Laser beam combining module, used to integrate beams of different frequencies into the same optical fiber output; The laser beam splitter module is used to output laser power to different optical fibers according to the required ratio; The frequency control module is used to adjust the output frequency of the laser to the frequency required to manipulate atoms. It has the function of adjusting the output optical power and serves as the optical switch response time to meet timing requirements. The optical switch module is used to achieve switch control with response time meeting timing requirements; The power stabilization module is used to achieve stable MOT and Molasses atomic signals; it collects and converts the output power of the six cooling beams used to achieve 3D-MOT into voltage signals in real time; for each pair of opposing cooling beams, one of the outputs is used as a reference power signal, and the control voltage of the power stabilization module installed in the opposing optical path is adjusted in real time to ensure that the optical power output of the optical fiber is consistent with the power of the reference optical signal.

2. The universal integrated all-fiber optical control system according to claim 1, characterized in that, The aforementioned fiber optic output method is either the laser is directly output from the fiber optic cable or a free-space beam is coupled into the fiber optic cable and output from the fiber optic cable.

3. The universal integrated all-fiber optical control system according to claim 1, characterized in that, The reference laser, cooling laser, and probe laser mentioned above are laser sources that manipulate the same isotope.

4. The universal integrated all-fiber optical control system according to claim 3, characterized in that, The number of light sources for the reference laser, cooling laser, and probe laser is greater than or equal to one; the light source can manipulate different isotopes of the same atom or different types of atoms.

5. The universal integrated all-fiber optical control system according to claim 1, characterized in that, The laser beam combining module requires two laser sources of different frequencies that meet the conditions for manipulating cold atoms; the two laser sources are different sources that manipulate the same alkaline earth metal element, including a cooling source and a heavy pump source; or the two laser sources are sources that manipulate different types of alkaline earth metals.

6. The universal integrated all-fiber optical control system according to claim 1, characterized in that, The laser beam combining module is divided into two types: The first type has two input optical signals of different frequencies, and the laser beam combining module has two outputs: each output contains two optical signals of different frequencies, and the ratio of the optical power of the different frequency optical signals depends on the beam combining ratio of the laser beam combining module for that frequency of laser; the ratio of the optical power of the same frequency in the two output optical signals depends on the beam combining ratio of the laser beam combining module for that frequency of laser. The second type has two input optical signals of different frequencies, and the laser beam combining module has only one output: the laser beam combining module outputs one optical signal containing two frequencies, and the ratio of the optical power of the different frequency optical signals depends on the beam combining ratio of the laser beam combining module for that frequency of laser.

7. The universal integrated all-fiber optical control system according to claim 1, characterized in that, The laser beam splitter module has one optical signal input and two optical signal outputs. The ratio of the optical power of the two optical signals depends on the beam splitting ratio of the laser beam splitter module for that frequency of laser.

8. The universal integrated all-fiber optical control system according to claim 1, characterized in that, The power stabilization module is designed to achieve stable MOT and molasses atomic signals. The output power of the six cooling beams used to achieve 3D-MOT is acquired in real time and converted into voltage signals. For each pair of opposing cooling beams, one of the outputs is used as a reference signal. The control voltage of the power stabilization module installed in the opposing optical path is adjusted in real time to ensure that the optical power output of the optical fiber is consistent with the power of the opposing optical signal.

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