A laser frequency-shift and power stabilizing device and atomic optical device

Abstract

The application provides a laser frequency shift and power stabilization device and an atomic optical device. The application utilizes the characteristic that the light path is unchanged after the laser passes through the acousto-optic modulator twice, avoids the defect that the light path is deflected after the acousto-optic modulator shifts the frequency, adds a power stabilization loop on this basis, can meet the needs of various kinds of lasers calling in time sequence, and can enhance the power stability of the output light. The application simultaneously realizes the functions of frequency shift and power stabilization, is helpful to simplify the test light path or realize the miniaturization of a large optical path system, can reduce the power loss caused by using too many components in the process of adjusting the laser characteristics, and can be widely applied to atomic optical related tests and optical systems of complex devices.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of laser control, and more particularly relates to a laser frequency-shifting and power stabilizing device and an atomic optical device. BACKGROUND

[0002] Since the first laser was realized in the 1950s, due to its monochromaticity, directionality, coherence and other characteristics different from ordinary light, it has been widely used in many scientific and technological fields. However, in practical applications, the frequency, power, polarization, direction and other parameters of the laser need to be controlled very finely, making the optical system structure very complex.

[0003] Taking the optical system of an atomic gravimeter as an example, in terms of frequency, different frequency lasers are needed to sequentially cool, select, interfere and detect atoms, at least seven different frequency lasers are needed, in addition to which, in the cooling stage, the frequency of the cooling light needs to be finely adjusted to achieve different degrees of cooling and control the initial motion direction of the atoms; in terms of power, in order to reduce noise in the measurement results and obtain stable and reliable gravity measurement results, power control of the laser is needed, mainly including Raman light and probe light, the Raman light can change the atomic energy state in the measurement process, and the probe light is used to measure the remaining number and type of atoms in the final stage, if there is power disturbance in these two kinds of light, it will directly affect the gravity measurement resolution; in terms of polarization, when the cold atoms are prepared, the laser polarization is required to be circularly polarized, and when the atomic interference is performed, the laser polarization is required to be linearly polarized; in addition, when the gravity information is measured, the propagation direction of the Raman light is required to be completely consistent with the direction of the gravity. These requirements need to be realized in the optical system. In practical applications, different parameters are usually controlled by different links, which makes it difficult to reduce the complexity of the optical system.

[0004] If appropriate devices or methods are selected to simultaneously adjust multiple parameters of the laser, the structure of the optical system can be effectively simplified, and power loss caused by a long optical path and too many components can be reduced.

[0005] To control the parameters of the laser, on the one hand, high-performance lasers are selected, so that the laser output light directly meets the demand, and the optical system can be simplified to the maximum extent. However, this method is not suitable for the case where the laser types are too many or the parameters are too complex, such as the optical system of an atomic gravimeter. On the other hand, various laser characteristic control units can be added outside the laser to obtain more types of laser. The external control unit does not affect the light source, has higher universality, and is easier to operate. Common laser characteristic control unit technologies include mode selection, frequency stabilization, Q modulation, mode locking, nonlinear frequency change, etc. To achieve the goal of laser frequency shift, the commonly used control unit is an acousto-optic modulator, which changes the frequency of the output light by adjusting the refractive index of the light passing through the crystal to cause diffraction. To achieve the goal of power stability, the commonly used control units include piezoelectric ceramics, magneto-optic modulators, electro-optic modulators, acousto-optic modulators, etc. Among them, the acousto-optic modulator has the advantages of small size, simple operation, high extinction ratio, and unique advantages in the application of quantum optics. Among these control units, the acousto-optic modulator can not only adjust the laser frequency, but also stabilize the laser power.

[0006] Therefore, it is necessary to design a device for the acousto-optic modulator, which has both frequency shifting and power stabilization functions, which is of great significance to reduce the complexity of the optical system. SUMMARY

[0007] The purpose of the present application is to provide a laser frequency shifting and power stabilization device and an atomic optical device, which can simultaneously realize the functions of power stabilization and frequency shifting, help to simplify the test optical path or realize the miniaturization of large optical path systems, and reduce the power loss caused by the excessive use of components during the adjustment of laser characteristics.

[0008] To achieve the above purpose, the first aspect of the present application provides a laser frequency shifting and power stabilization device, which comprises the following components: a laser, a first 1 / 2 wave plate, a first polarization beam splitter, a second 1 / 2 wave plate, a first lens, a first diaphragm, an acousto-optic modulator, a second diaphragm, a second lens, a 1 / 4 wave plate, a mirror, a third 1 / 2 wave plate, a second polarization beam splitter, a photodetector, an upper computer, a controller, and an acousto-optic modulator driver.

[0009] The laser output by the laser is adjusted in polarization state by a first 1 / 2 wave plate, enters a first polarization beam splitter, and is separated into first vertical linearly polarized light and first horizontal linearly polarized light in the first polarization beam splitter, the first vertical linearly polarized light is reflected by the first polarization beam splitter to outside the optical path, and the first horizontal linearly polarized light is transmitted into a second 1 / 2 wave plate to adjust the polarization state into linearly polarized collimated light, the linearly polarized collimated light enters a first lens and a first light aperture in turn, is incident into an acousto-optic modulator to be frequency-shifted once, the light emitted by the acousto-optic modulator after being frequency-shifted once passes through a second light aperture, a second lens, a 1 / 4 wave plate and a mirror in turn and is reflected along the original path, reenters the acousto-optic modulator to be frequency-shifted twice, the light emitted by the acousto-optic modulator after being frequency-shifted twice passes through the first light aperture, the first lens and the second 1 / 2 wave plate in turn, is separated into second vertical linearly polarized light and second horizontal linearly polarized light in the first polarization beam splitter, the second horizontal linearly polarized light is transmitted to outside the optical path, and the second vertical linearly polarized light is reflected by the first polarization beam splitter into a third 1 / 2 wave plate to adjust the polarization state, the light signal adjusted in polarization state enters a second polarization beam splitter and is separated into third vertical linearly polarized light and third horizontal linearly polarized light, the third vertical linearly polarized light is reflected by the second polarization beam splitter as output light, and the third horizontal linearly polarized light is transmitted from the second polarization beam splitter as control light.

[0010] The photodetector is used to convert the power information of the control light into a measured voltage of the control light; the host computer is used to set the frequency-shift amount of the output light and a reference power, the host computer calculates a reference voltage of the control light according to the reference power, the light splitting ratio of the second polarization beam splitter and the power-voltage conversion gain of the photodetector; the controller is used to convert the frequency-shift amount of the output light into a frequency control signal, and convert the difference between the measured voltage of the control light and the reference voltage of the control light into an amplitude control signal; and the acousto-optic modulator driver generates a driving signal according to the amplitude control signal and the frequency control signal, and drives the acousto-optic modulator to adjust the refractive index of the acousto-optic medium to the light, so as to frequency-shift and control the power of the output light.

[0011] Further, the first 1 / 2 wave plate, the second 1 / 2 wave plate and the third 1 / 2 wave plate are used to adjust the polarization state of the laser, so that the proportion of horizontal linearly polarized light and vertical linearly polarized light in the laser changes.

[0012] Further, the first lens and the second lens are used to focus the light beam, and the focal point is located at the center of the acousto-optic modulator.

[0013] Further, the first light aperture and the second light aperture are used to limit the light beam path.

[0014] Further, the light beam focused by the first lens passes through the first diaphragm, diffracts in the acousto-optic modulator, the 0th order light is blocked by the second diaphragm, and the '+1' order light passes through the second diaphragm and is converted into linearly polarized collimated light by the second lens; or the light beam focused by the second lens passes through the second diaphragm, diffracts in the acousto-optic modulator, the 0th order light is blocked by the first diaphragm, and the '+1' order light passes through the first diaphragm and is converted into linearly polarized collimated light by the first lens into the second 1 / 2 wave plate.

[0015] Further, the linearly polarized collimated light from the second lens is converted into circularly polarized light by the 1 / 4 wave plate; or the circularly polarized light reflected by the mirror is converted into linearly polarized collimated light by the 1 / 4 wave plate into the second lens.

[0016] Further, the calculation process of the reference voltage is as follows:

[0017] Let the control optical power be P control , the reference power be P0, and the splitting ratio of the second polarization beam splitter be The power-voltage conversion gain of the photodetector is The calculation formula of the reference voltage U0 is

[0018]

[0019] Further, the process of the controller giving the frequency control signal is as follows:

[0020] Let the frequency shift amount of the output light reflected by the second polarization beam splitter specified by the host computer be ω s , and the frequency control signal be U f , then

[0021] The process of the controller giving the amplitude control signal is as follows:

[0022] Let the measured voltage be U, the reference voltage be U0, and the difference e p between the reference voltage and the measured voltage be U0-U, e p (n), e p (n-1), and e p (n-2) be the difference values after the nth, n-1th, and n-2th sampling, respectively, K p , K i , and K d be the proportional coefficient, integral coefficient, and differential coefficient of the PID control algorithm, respectively, and the amplitude control signal U p be obtained by using the basic PID control algorithm, and the calculation formula is as follows:

[0023]

[0024] The second aspect of the present application also provides an atomic optical device, wherein the optical system of the measuring device of the atomic optical device comprises the laser frequency-shifting and power stabilizing device.

[0025] Further, the atomic optical device is an atomic gravimeter or an atomic clock.

[0026] Further, the laser is a 780 nm single-frequency laser emitter.

[0027] Further, the frequency range that the acousto-optic modulator driver can drive is within the factory bandwidth of the acousto-optic modulator.

[0028] Further, the laser frequency output by the laser is ω, and the specified frequency shift amount in the host computer is ω s , and the frequency of the output light of the second polarization beam splitter is ω+2ω s .

[0029] Compared with the prior art, the present application has the following technical effects:

[0030] The laser frequency-shifting and power stabilizing device can simultaneously realize the functions of power stabilization and frequency shifting, which helps to simplify the test optical path or realize the miniaturization of large optical path systems, and can reduce the power loss caused by excessive use of components in the process of adjusting the laser characteristics. The laser frequency-shifting and power stabilizing device utilizes the characteristic that the optical path remains unchanged after the laser passes through the acousto-optic modulator twice, avoids the defect that the optical path is deflected after the acousto-optic modulator shifts the frequency, expands the frequency shift range, increases the reliability of the optical path, and generates multiple frequency light using one optical path, which can meet the demand of calling various types of lasers in time sequence in actual application. The laser frequency-shifting and power stabilizing device shifts the frequency of the laser twice through the acousto-optic modulator, and uses a polarization beam splitter to split a beam for power stabilization, which overcomes the influence of large light power fluctuation after frequency shifting on precise measurement tests, and can meet the requirements of light power stability in the process of calling various types of lasers in time sequence.

[0031] The laser frequency-shifting and power stabilizing device can be applied to systems that need to control the frequency and power of the laser simultaneously, such as the optical system of the measuring device used in atomic optical related tests, such as atomic gravimeters, atomic clocks, etc. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0033] Figure 1 A structural schematic diagram of a laser frequency shift and power stabilization device provided by the embodiment of the present application;

[0034] Figure 2 A frequency shift effect schematic diagram of a laser frequency shift and power stabilization device provided by the embodiment of the present application;

[0035] Figure 3 A power stabilization effect schematic diagram of a laser frequency shift and power stabilization device provided by the embodiment of the present application.

[0036] In the drawings, various reference signs represent:

[0037] 1, laser, 2, first 1 / 2 wave plate, 3, first polarization beam splitter, 4, second 1 / 2 wave plate, 5, first lens, 6, first diaphragm, 7, acousto-optic modulator, 8, second diaphragm, 9, second lens, 10, 1 / 4 wave plate, 11, mirror, 12, third 1 / 2 wave plate, 13, second polarization beam splitter, 14, photodetector, 15, host computer, 16, controller, 17, acousto-optic modulator driver. DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and beneficial effects of the present application more clearly understood, the following will further describe the present application with embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not used to limit the present application.

[0039] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0040] The terms "first", "second" are only for the purpose of description, used to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX can also be called the second XX, and similarly, the second XX can also be called the first XX. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more features.

[0041] The embodiment of the present application provides a laser frequency shift and power stabilizing device, and the structure is as shown in the figure Figure 1 The device comprises a laser 1, a first 1 / 2 wave plate 2, a first polarization beam splitter 3, a second 1 / 2 wave plate 4, a first lens 5, a first diaphragm 6, an acousto-optic modulator 7, a second diaphragm 8, a second lens 9, a 1 / 4 wave plate 10, a mirror 11, a third 1 / 2 wave plate 12, a second polarization beam splitter 13, a photodetector 14, an upper computer 15, a controller 16 and an acousto-optic modulator driver 17.

[0042] The first 1 / 2 wave plate 2, the second 1 / 2 wave plate 4 and the third 1 / 2 wave plate 12 are used for adjusting the polarization state of laser, so that the proportion of horizontal linearly polarized light and vertical linearly polarized light in the laser is changed. The first lens 5 and the second lens 9 are used for focusing light beams, and the focal points are located at the center of the acousto-optic modulator 7. The first diaphragm 6 and the second diaphragm 8 are used for limiting the light beam path.

[0043] The working process of the laser frequency-shifting and power stabilizing device is as follows: the laser 1 outputs single-frequency laser of 780nm, the single-frequency laser is adjusted in polarization state at the first 1 / 2 glass 2, so that the proportion of horizontal linearly polarized light in the laser is maximum, the laser after the polarization state adjustment enters the first polarization beam splitter 3 and is separated into first vertical linearly polarized light and first horizontal linearly polarized light in the first polarization beam splitter 3, the first vertical linearly polarized light is reflected by the first polarization beam splitter 3 to the outside of the light path, and the first horizontal linearly polarized light is transmitted into the second 1 / 2 glass 4 and is adjusted in polarization state to become linearly polarized collimated light, the second 1 / 2 glass 4 changes the polarization state of the horizontal linearly polarized light, so that the proportion of the horizontal linearly polarized light and the vertical linearly polarized light in the laser changes. The linearly polarized collimated light passes through the first lens 5, and the light beam is gradually focused, the focal point is located at the center of the acousto-optic modulator 7, the focused light enters the acousto-optic modulator 7 after passing through the first diaphragm 6, and the first diaphragm 6 is blocked, and the'+1'order light passes through the second diaphragm 8 and is converted into collimated light by the second lens 9. The linearly polarized collimated light is converted into circularly polarized light by the 1 / 4 glass 10, the circularly polarized light is reflected by the mirror 11, the reflected circularly polarized light is converted into linearly polarized collimated light by the 1 / 4 glass 10, the linearly polarized collimated light passes through the second lens 9, and the light beam is gradually focused, the focal point is located at the center of the acousto-optic modulator 7, the focused light enters the acousto-optic modulator 7 after passing through the second diaphragm 8, and the second diaphragm 8 is blocked, and the'+1'order light passes through the first diaphragm 6 and is adjusted in polarization state at the second 1 / 2 glass 4, so that the proportion of the vertical linearly polarized light in the laser is maximum. The laser after the polarization state adjustment is separated into second vertical linearly polarized light and second horizontal linearly polarized light in the first polarization beam splitter 3, the second horizontal linearly polarized light is transmitted to the outside of the light path, and the second vertical linearly polarized light is reflected by the first polarization beam splitter 3 and enters the third 1 / 2 glass 12 and is adjusted in polarization state at the third 1 / 2 glass 12, so that the proportion of the vertical linearly polarized light in the laser is larger. The laser after the polarization state adjustment enters the second polarization beam splitter 13 and is separated into third vertical linearly polarized light and third horizontal linearly polarized light in the second polarization beam splitter 13, the third vertical linearly polarized light is reflected by the second polarization beam splitter 13 and is output as light, and the third horizontal linearly polarized light is transmitted from the second polarization beam splitter 13 and is detected by the photodetector 14 as control light and is converted into a control light measured voltage.The host computer 15 sets the frequency shift amount and the reference power of the output light reflected by the second polarization beam splitter 13, and the host computer 15 calculates the control light reference voltage according to the set reference power, the splitting ratio of the second polarization beam splitter 13, and the power-voltage conversion gain of the photodetector 14. The controller 16 converts the frequency shift amount specified by the host computer 15 into a frequency control signal and outputs the frequency control signal to the acousto-optic modulator driver 17, and the controller 16 converts the difference between the control light measured voltage converted by the photodetector 14 and the control light reference voltage calculated by the host computer 15 into an amplitude control signal and outputs the amplitude control signal to the acousto-optic modulator driver 17. The acousto-optic modulator driver 17 generates a driving signal according to the amplitude control signal and the frequency control signal, and drives the acousto-optic modulator 7 to adjust the refractive index of the acousto-optic medium to the light, so as to realize the frequency shift and the power control of the output light. Finally, the reflected light output from the second polarization beam splitter 13 is the output light which has been subjected to twice frequency shift and power control.

[0044] The laser 1 in the embodiment of the present application is a single-frequency laser transmitter with a wavelength of 780 nm. The frequency range that can be driven by the acousto-optic modulator driver 17 is within the factory bandwidth of the acousto-optic modulator 7. In the embodiment of the present application, in order to realize the laser frequency shift, the host computer 15 is used to set the frequency shift amount of the output light reflected by the second polarization beam splitter 13, and the frequency difference between the output light and the input light will be twice the frequency shift amount. For example, let the frequency of the laser output by the laser 1 be ω, and the frequency shift amount specified in the host computer 15 be ω s , then the frequency of the output light of the second polarization beam splitter 13 is ω+2ω s .

[0045] In order to realize the power stabilization, the host computer 15 is used to set the reference power of the output light reflected by the second polarization beam splitter 13, and the output light power will always be stabilized around the reference power.

[0046] In the embodiment of the present application, the process of calculating the reference voltage by the host computer 15 is as follows:

[0047] Let the control light power be P control , the reference power be P0, and the splitting ratio of the second polarization beam splitter 13 be The power-voltage conversion gain of the photodetector 14 is Then the reference voltage U0 is calculated as follows:

[0048]

[0049] The process of the controller 16 to output the frequency control signal and the amplitude control signal is as follows:

[0050] The frequency shift amount ω s (MHz) and the frequency control signal U fThe frequency-voltage conversion gain relationship used in the embodiment of the present application is:

[0051]

[0052] The measured voltage is U, and the difference e between the measured voltage and the reference voltage p = U0-U, e p (n), e p (n-1), e p (n-2) are the differences obtained after the n, n-1, and n-2 sampling, respectively, K p , K i , K d are the proportional coefficient, integral coefficient, and differential coefficient of the PID control algorithm, respectively, and the amplitude control signal U p is obtained by using the basic PID control algorithm, and the calculation formula is as follows:

[0053]

[0054] In a specific embodiment, the specific parameters of each component are as follows:

[0055] The laser 1 is a semiconductor laser integrated with a frequency locking function; the frequency stabilized laser of the KU Leuven Company is used in this embodiment. The output wavelength is set to 780 nm, the laser line width is <1 MHz, the laser output power is 30 mW, the power stability is ≤2% @1h, and the frequency stability is <1 MHz @1h.

[0056] The first 1 / 2 wave plate 2, the second 1 / 2 wave plate 4, and the third 1 / 2 wave plate 12 are all composed of multiple quartz wave plates. The zero-level 1 / 2 wave plate WPHSM05-780 of the Thorlabs Company is used in this embodiment, and the light aperture is 10 mm.

[0057] The first polarization beam splitter 3 and the second polarization beam splitter 13 are both polarization beam splitting prisms, which transmit horizontally polarized state laser and reflect vertically polarized state laser, and the power ratio of the transmitted laser and the reflected laser is controlled by the 1 / 2 wave plate. In this embodiment, a 1-inch laser spectral line polarization beam splitting cube mounted in a 30 mm cage cube is used, the bevel of each beam splitting cube is coated with a laser spectral line beam splitting film to provide an extinction ratio of >3000:1. The right-angle surface is coated with an anti-reflection film, and the R avg <0.25%.

[0058] The first lens 5 and the second lens 9 are used for focusing or collimating the laser. In this embodiment, the plano-convex lens CX10613-AB produced by Lbtek Company is used, the optical material is N-BK7, the diameter is 25.4 mm, the focal length is 100.0 mm, and the center thickness is 3.6 mm.

[0059] The first diaphragm 6 and the second diaphragm 8 are used for limiting the laser path. In this embodiment, the adjustable diaphragm DPP12 produced by Lbtek Company is used, the light passing hole diameter is 1 mm to 12 mm, and a dial rod is provided.

[0060] The acousto-optic modulator 7 modulates the input laser, and outputs '-1' level light, '0' level light and '+1' level light. The acousto-optic modulator 7 can control the power ratio of '0' level and '±1' level by inputting microwave power. The '0' level light and the '±1' level light are in the same direction, and the frequency difference is one modulation frequency. In this embodiment, the SGT110-780-1TA-B50 acousto-optic modulator produced by Zhongdianke Chip Technology Co., Ltd. is used, the working wavelength is 780±20 nm, the center frequency is 110 MHz, and the full bandwidth diffraction efficiency is greater than or equal to 70%.

[0061] The 1 / 4 wave plate 10 is made of liquid crystal polymer. In this embodiment, the polymer true zero-order quarter wave plate QWP25-780A-M produced by Lbtek Company is used, the light passing hole diameter is 21.5 mm, and the working wavelength is 780 nm.

[0062] The reflecting mirror 11 is used for deflecting the laser with normal incidence by 180° and reflecting it out. In this embodiment, the dielectric film reflecting mirror BDM1-B-P10 produced by Lbtek Company is used, the diameter is 25.4 mm, the working wavelength is 750-1100 nm, and the thickness is 6 mm.

[0063] The photodetector 14 converts the optical power information into a measured voltage. In this embodiment, the free-space balanced photodetector PDB210A / M produced by Thorlabs Company is used, the active area diameter is 5 mm, and the wavelength range is 320-1060 nm.

[0064] The acousto-optic modulator driver 17 converts the control signal into a driving signal to drive the acousto-optic modulator to work. In this embodiment, the double-channel AOM driver CA-AOMD-110-A1 produced by Zhongke Kuyuan Company is used, the frequency range is 60-160 MHz, the radio frequency output power is less than 34 dBm, and the radio frequency switch isolation is greater than or equal to 50 dB.

[0065] Since it is impossible to observe the frequencies of the input and output light simultaneously, the frequency of the input light from laser 1 was first locked around 384228115.2MHz, ensuring that the frequency fluctuation was less than 10MHz. Using the host computer 15, the frequency shift was set to 90Hz and 110Hz, with a reference power of 0.5mW. The difference between the frequency of the output light from the second polarization beam splitter 13 and 384228115.2MHz was observed. The results are shown in the attached figure. Figure 2 As shown in the attached figure, the power variation of the output light is as follows. Figure 3 As shown.

[0066] In the appendix Figure 2 In this process, due to fluctuations in the input light frequency, the output light frequency also fluctuates to some extent, but the frequency difference between the input and output light remains stable around 180MHz and 220MHz. (See attached...) Figure 3 As can be seen, the output optical power fluctuates due to frequency variations, but it can quickly stabilize to near the reference power under the action of the power stabilization circuit. This demonstrates that the device in this embodiment of the invention can effectively achieve frequency shifting and power stabilization.

[0067] The laser frequency shifting and power stabilization device of this invention combines the advantages of the acousto-optic modulator 7, which can simultaneously modulate the frequency and amplitude of light. It can use a single acousto-optic modulator 7 to perform multiple controls on the output light frequency and power, greatly simplifying the optical path and thus significantly reducing the light loss of components.

[0068] This invention provides a laser frequency shifting and power stabilization device that utilizes the characteristic that the optical path remains unchanged after the laser passes through the acousto-optic modulator 7 twice, avoiding the drawback of optical path deflection after frequency shifting in the acousto-optic modulator 7. Furthermore, by adding a power stabilization loop, it can meet the timing requirements of various types of lasers and enhance the power stability of the output light. This invention simultaneously achieves frequency shifting and power stabilization, which helps simplify experimental optical paths or achieve miniaturization of large optical systems. It also reduces power loss caused by excessive components during laser characteristic adjustment and can be widely applied in atomic optics-related experiments and optical systems of complex devices.

[0069] Furthermore, embodiments of the present invention also provide an atomic optical device, the optical system of which includes the laser frequency shifting and power stabilization device described above. For example, the atomic optical device can be an atomic gravimeter or an atomic clock.

[0070] The atomic optical device in this embodiment of the invention has the laser frequency shifting and power stabilization device of this invention, and therefore also has the beneficial effects of the laser frequency shifting and power stabilization device described above, which will not be repeated here.

[0071] The above embodiments only express several implementation manners of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A laser frequency shifting and power stabilization device, characterized in that, It includes a laser (1), a first half-wave plate (2), a first polarizing beam splitter (3), a second half-wave plate (4), a first lens (5), a first aperture (6), an acousto-optic modulator (7), a second aperture (8), a second lens (9), a quarter-wave plate (10), a mirror (11), a third half-wave plate (12), a second polarizing beam splitter (13), a photodetector (14), a host computer (15), a controller (16), and an acousto-optic modulator driver (17); The laser output from the laser (1) is polarized by the first half-wave plate (2) and enters the first polarization beam splitter (3). The laser, after polarization adjustment, is split into first vertical linearly polarized light and first horizontal linearly polarized light in the first polarization beam splitter (3). The first vertical linearly polarized light is reflected out of the optical path by the first polarization beam splitter (3). The first horizontal linearly polarized light is transmitted into the second half-wave plate (4) and its polarization is adjusted to become linearly polarized collimated light. The linearly polarized collimated light passes through the first lens (5) and the first aperture (6) in sequence and then enters the acousto-optic modulator (7) for one frequency shift. The outgoing light after one frequency shift by the acousto-optic modulator (7) passes through the second aperture (8), the second lens (9), and the quarter-wave plate (10) in sequence and is reflected by the mirror (11) and returns along the original path, entering the second half-wave plate (4) again. The acoustic-optic modulator (7) performs a second frequency shift. The outgoing light after the second frequency shift by the acoustic-optic modulator (7) passes through the first aperture (6), the first lens (5), and the second half-wave plate (4) in sequence. It is then separated into a second vertically polarized light and a second horizontally polarized light in the first polarization beam splitter (3). The second horizontally polarized light is transmitted outside the optical path. The second vertically polarized light is reflected by the first polarization beam splitter (3) and enters the third half-wave plate (12) to adjust its polarization state. The light signal with the adjusted polarization state enters the second polarization beam splitter (13) and is separated into a third vertically polarized light and a third horizontally polarized light. The third vertically polarized light is reflected by the second polarization beam splitter (13) and becomes the output light. The third horizontally polarized light is transmitted from the second polarization beam splitter (13) and becomes the control light. The photodetector (14) is used to convert the power information of the control light into the measured voltage of the control light; the host computer (15) is used to set the frequency shift amount and reference power of the output light. The host computer (15) calculates the reference voltage of the control light based on the reference power, the splitting ratio of the second polarization beam splitter (13), and the power-to-voltage conversion gain of the photodetector (14); the controller (16) is used to convert the frequency shift amount of the output light into a frequency control signal. The controller (16) converts the difference between the measured voltage of the control light and the reference voltage of the control light into an amplitude control signal; the acousto-optic modulator driver (17) generates a drive signal based on the amplitude control signal and the frequency control signal. The drive signal drives the acousto-optic modulator (7) to adjust the refractive index of the acousto-optic medium for light, thereby performing frequency shifting and optical power control on the output light.

2. The laser frequency shifting and power stabilization device as described in claim 1, characterized in that, The first half-wave plate (2), the second half-wave plate (4), and the third half-wave plate (12) are used to adjust the polarization state of the laser, thereby changing the ratio of horizontally polarized light to vertically polarized light in the laser.

3. The laser frequency shifting and power stabilization device as described in claim 1, characterized in that, The first lens (5) and the second lens (9) are used to focus the light beam, with the focal point located at the center of the acousto-optic modulator (7).

4. The laser frequency shifting and power stabilization device as described in claim 1, characterized in that, The first aperture (6) and the second aperture (8) are used to limit the beam path.

5. The laser frequency shifting and power stabilization device as described in claim 1, characterized in that, After being focused by the first lens (5), the light beam passes through the first aperture (6) and then diffracts in the acousto-optic modulator (7). The 0th order light is blocked by the second aperture (8), and the +1 order light passes through the second aperture (8) and is converted into linearly polarized collimated light by the second lens (9). Alternatively, after being focused by the second lens (9), the light beam passes through the second aperture (8) and then diffracts in the acousto-optic modulator (7). The 0th order light is blocked by the first aperture (6), and the +1 order light passes through the first aperture (6) and is converted into linearly polarized collimated light by the first lens (5) before entering the second 1 / 2 glass slide (4).

6. The laser frequency shifting and power stabilization device as described in claim 1, characterized in that, Linearly polarized collimated light from the second lens (9) is converted into circularly polarized light after passing through the quarter-wave plate (10); or circularly polarized light reflected by the mirror (11) is converted into linearly polarized collimated light after passing through the quarter-wave plate (10) and enters the second lens (9).

7. The laser frequency shifting and power stabilization device as described in claim 1, characterized in that, The calculation process for the reference voltage is as follows: Let the controlled optical power be P. control The reference power is P0, and the splitting ratio of the second polarization beam splitter (13) is... The power-to-voltage conversion gain of the photodetector (14) is The formula for calculating the reference voltage U0 is:

8. The laser frequency shifting and power stabilization device as described in claim 1, characterized in that, The process by which the controller (16) provides the frequency control signal is as follows: Let ω be the frequency shift of the output light reflected from the second polarizing beam splitter (13) as specified by the host computer (15). s Let the frequency control signal be U. f ,but The process by which the controller (16) gives the amplitude control signal is as follows: Let the measured voltage be U, the reference voltage be U0, and the difference between the reference voltage and the measured voltage be e. p =U0-U,e p (n), e p (n-1), e p (n-2) represent the differences obtained after the nth, n-1th, and n-2th samples, respectively, and K p K i K d These are the proportional coefficient, integral coefficient, and derivative coefficient of the PID control algorithm, respectively. The amplitude control signal U is obtained using the basic PID control algorithm. p The calculation formula is as follows:

9. An atomic optical device, characterized in that, The optical system of the measuring device includes the laser frequency shifting and power stabilization device as described in any one of claims 1-8.

10. An atomic optical device as described in claim 9, characterized in that, The atomic optical device is an atomic gravimeter or an atomic clock.

Images