Raman light phase rapid shear device and method

Abstract

The invention belongs to the field of atomic interference precision measurement, and particularly discloses a Raman light phase rapid shear device and method. According to the invention, the signal generation module generates the modulation signal which is matched with the target Raman light in frequency difference and is rapidly sheared in phase, and the phase modulator directly loads the phase jump sequence to the Raman light. According to the design, a modulation signal is accurately aligned with a first-order sideband of Raman light, so that two beams of light do not need to be modulated separately, and a complex light path structure in a traditional scheme is simplified; meanwhile, the two frequency components are transmitted in the same device, so that additional phase noise introduced by independent control of branches is avoided. Finally, the device realizes rapid phase shear of Raman light, and the system complexity and phase noise are remarkably reduced while the modulation precision is ensured.

Description

Technical Field

[0001] This application belongs to the field of atomic interferometry precision measurement, specifically relating to a Raman optical phase rapid shearing device and method. Background Technology

[0002] Atomic interferometers, measuring instruments based on the interference properties of matter waves, have become crucial tools in the field of high-precision measurement. Quantum optimization control, by optimizing the pulse form (amplitude, phase, and frequency) according to specific objectives, can effectively improve the performance of atomic interferometers.

[0003] Currently, the work on using optimized pulses to improve interferometer performance basically includes the following two types. The first is to use optimized pulses to compensate for the inhomogeneity of atomic velocity and laser intensity. Raman light consists of two laser beams with a fixed frequency difference. Existing technology uses a dual parallel Mach-Zehnder interferometer to modulate the Raman light. First, a phase change is applied to one of the beams, and then the two beams are combined. Although this method achieves phase control of the Raman light, the two beams are spatially separated. Ground vibrations and temperature changes will introduce significant phase noise into the Raman light, which is not conducive to high-precision measurements.

[0004] Next, robustly optimized pulses are used to enhance the sensitivity of the atomic interferometer. Bragg pulses are also composed of two laser beams with a certain frequency difference. Existing technology loads robustly optimized pulses onto Bragg pulses and uses an acousto-optic modulator to modulate the frequency, amplitude, and phase of the light, while also modulating the two beams separately. In the aforementioned work, the method of generating optimized pulses using a dual parallel Mach-Zehnder interferometer involves modulating the two beams separately. This approach not only leads to a complex optical path structure but also introduces additional phase noise when applied to Raman light, hindering high-precision measurements. Furthermore, using an acousto-optic modulator to generate optimized pulses still results in the two beams being generated separately, complicating optical path setup and causing a series of operational inconveniences. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a Raman light phase fast switching device and method, which aims to solve the problem that the traditional method of generating phase-jump Raman light requires two beams to be modulated separately, which is complicated in optical path construction and introduces additional phase noise.

[0006] The first aspect of this application relates to a Raman light phase-fast switching device, comprising: a signal generation module and a phase modulator; the output terminal of the signal generation module is connected to a first input terminal of the phase modulator; the second input terminal of the phase modulator is connected to the output terminal of an incident light source; the signal generation module is configured to generate a modulation signal containing a predetermined phase-jump sequence and output it to the phase modulator, wherein the frequency of the modulation signal matches the frequency difference between two frequency components of the target Raman light; the phase modulator is configured to load the phase change of the modulation signal onto the incident light to generate Raman light with rapid phase switching.

[0007] In one embodiment, the signal generation module includes: a phase transition generation unit, a first mixing unit, and a second mixing unit; the output terminal of the phase transition generation unit is connected to the input terminal of the first mixing unit; the output terminal of the first mixing unit is connected to the input terminal of the second mixing unit; the output terminal of the second mixing unit is connected to the first input terminal of the phase modulator; the phase transition generation unit is configured to output a phase transition signal to the first mixing unit based on a predetermined phase transition sequence; the first mixing unit is configured to mix and filter the phase transition signal with a preset fixed-frequency sine wave source to generate an intermediate-frequency phase transition signal and output it to the second mixing unit; the second mixing unit is configured to mix and filter the intermediate-frequency phase transition signal with a first high-frequency microwave source to generate a high-frequency phase transition signal as a modulation signal and output it to the phase modulator.

[0008] In one embodiment, the phase transition generation unit includes: a first waveform generator; the output of the first waveform generator is connected to the input of a first mixer unit; the first waveform generator is configured to generate a baseband phase modulation signal containing a predetermined phase transition sequence, as a phase transition signal output.

[0009] In one embodiment, the first mixing unit includes: a second waveform generator, a first mixer, and a first filter; the first input terminal of the first mixer is connected to the output terminal of the phase transition generation unit, and the second input terminal of the first mixer is connected to the output terminal of the second waveform generator; the output terminal of the first mixer is connected to the input terminal of the first filter; the output terminal of the first filter is connected to the input terminal of the second mixing unit; the second waveform generator is configured to generate a sinusoidal signal of a fixed frequency as a preset fixed-frequency sinusoidal source.

[0010] In one embodiment, the second mixing unit includes: a first high-frequency microwave source, a second mixer, and a second filter; the first input terminal of the second mixer is connected to the output terminal of the first mixing unit, and the second input terminal of the second mixer is connected to the output terminal of the first high-frequency microwave source; the output terminal of the second mixer is connected to the input terminal of the second filter; the output terminal of the second filter is connected to the first input terminal of a phase modulator; the first high-frequency microwave source is configured to participate in mixing so that the second mixer generates a high-frequency microwave signal with a frequency equal to the frequency difference between the two frequency components of the target Raman light.

[0011] In one embodiment, the Raman light phase fast shearing device further includes: a detection module; the input of the detection module is connected to the output of the phase modulator; the detection module is configured to acquire the phase information of the modulated Raman light to verify the modulation result.

[0012] In one embodiment, the detection module includes: an optocoupler, a photodetector, a second high-frequency microwave source, a third mixer, a third filter, and an oscilloscope; the input terminal of the optocoupler is coupled to the output optical path of the phase modulator; the output terminal of the optocoupler is connected to the optical input port of the photodetector; the electrical output port of the photodetector is connected to the first input terminal of the third mixer; the output terminal of the second high-frequency microwave source is connected to the second input terminal of the third mixer; the output terminal of the third mixer is connected to the input terminal of the third filter; the output terminal of the third filter is connected to the signal input channel of the oscilloscope; the third mixer is configured to mix the first electrical signal detected by the photodetector with the signal from the second high-frequency microwave source to generate an intermediate frequency signal that the oscilloscope can acquire and analyze, so as to demodulate the applied phase transition information.

[0013] The second aspect of this application relates to a method for rapid phase switching of Raman light, comprising: generating a phase-switching signal based on a predetermined phase-switching sequence; mixing the phase-switching signal according to the frequency difference between two frequency components of the target Raman light to generate a modulation signal that matches the frequency difference between the two frequency components of the target Raman light; and loading the predetermined phase-switching sequence onto the incident light through a phase modulator according to the modulation signal to output Raman light with rapid phase switching.

[0014] In one embodiment, based on the modulation signal, a predetermined phase-switching sequence is loaded onto the incident light through a phase modulator to output Raman light with rapidly changing phase. The method further includes: coupling a first optical signal based on the rapidly changing phase Raman light and outputting a first electrical signal through photoelectric conversion; mixing the first electrical signal to generate a second electrical signal with a reduced frequency; and demodulating the second electrical signal to obtain the phase information of the modulated Raman light.

[0015] In one embodiment, the second electrical signal is demodulated to obtain the phase information of the modulated Raman light, and then the method further includes: comparing the phase information of the Raman light with the phase rapidly changing phase with a predetermined phase jump sequence to obtain the comparison result, and adjusting the predetermined phase jump sequence based on the comparison result.

[0016] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: This application employs a technique integrating a signal generation module and a phase modulator. First, the signal generation module generates a modulation signal whose frequency matches the frequency difference between the two frequency components of the target Raman light and whose phase changes rapidly. This allows the modulation signal to be precisely aligned with the first-order sideband of the Raman light, enabling subsequent direct overall modulation of the Raman light. Next, the phase modulator applies the phase changes of the modulation signal, containing a predetermined phase-jump sequence, to the incident light, generating Raman light with rapidly changing phase. Since the phase modulator can simultaneously transmit both frequency components within a single device, this not only eliminates the additional phase noise introduced by optical path separation and independent control during separate modulation but also simplifies the system structure through integrated design.

[0017] Ultimately, compared with existing technologies, this application achieves rapid phase shearing of Raman light, which improves modulation efficiency and stability while reducing system complexity and phase error, thereby solving the problems of complex optical paths and increased noise in traditional methods. Attached Figure Description

[0018] Figure 1 This is one of the structural block diagrams of the Raman optical phase fast shearing device provided in the embodiments of this application; Figure 2 This is a structural block diagram of the signal generation module provided in an embodiment of this application; Figure 3 This is a device selection and connection diagram of the signal generation module provided in the embodiments of this application; Figure 4 This is the second structural block diagram of the Raman optical phase fast shearing device provided in the embodiments of this application; Figure 5 This is a component selection and connection diagram of the detection module provided in the embodiments of this application; Figure 6 This is a schematic flowchart of the Raman optical phase fast shearing method provided in the embodiments of this application; Figure 7 This is a schematic diagram of phase changes provided in an embodiment of this application; Figure 8 This is a schematic diagram of the results of the phase fast shear provided in the embodiments of this application.

[0019] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 10 is a signal generation module; 11 is a phase transition generation unit; 111 is a first waveform generator; 12 is a first mixer unit; 121 is a second waveform generator; 122 is a first mixer; 123 is a first filter; 13 is a second mixer unit; 131 is a first high-frequency microwave source; 132 is a second mixer; 133 is a second filter; 20 is a phase modulator; 30 is a detection module; 301 is an optocoupler; 302 is a photodetector; 303 is a second high-frequency microwave source; 304 is a third mixer; 305 is a third filter; 306 is an oscilloscope. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. In this application, the symbol " / " indicates that the related objects are in an "or" relationship, for example, A / B means A or B.

[0022] In this application, the terms "first" and "second," etc., are used to distinguish different objects, not to describe a specific order of objects. For example, "first response message" and "second response message," etc., are used to distinguish different response messages, not to describe a specific order of response messages.

[0023] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0024] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0025] Applying a rapid phase shift to Raman pulses, also known as pulse optimization, is a key technique for effectively improving the performance of atomic interferometers. This is primarily used to suppress systematic errors, enhance robustness, and potentially improve immunity to specific noise. This is because the core of an atomic interferometer is the interaction between two laser beams with a frequency difference—Raman light—and atoms. Through three pulse sequences, the internal and momentum states of the atoms are coherently manipulated to form an interference loop.

[0026] However, phase noise caused by laser vibration, acoustic disturbances, or the laser itself is directly transmitted to atoms, causing interference fringes to shift. This is one of the main factors limiting the stability and accuracy of interferometers, especially for precision measurements with long interference times. Rapid phase shearing can cleverly cancel out noise by rapidly and deterministically changing the phase of the laser during the application of a Raman pulse.

[0027] Based on this, this application proposes a Raman optical phase fast shearing device. Please refer to... Figure 1 , Figure 1 This is one of the structural block diagrams of the Raman optical phase fast shearing device provided in the embodiments of this application.

[0028] In this embodiment, the Raman optical phase fast shear device includes a signal generation module 10 and a phase modulator 20.

[0029] It should be noted that the output terminal of the signal generation module 10 is connected to the first input terminal of the phase modulator 20; the second input terminal of the phase modulator 20 is connected to the output terminal of the incident light source.

[0030] It is understandable that the output terminal of the signal generation module 10 is electrically connected to the first input terminal of the phase modulator 20, mainly for transmitting the modulation drive signal; at the same time, the second input terminal of the phase modulator 20 is optically connected or coupled to the output optical path of the incident light source, and is used to receive the continuous or pulsed Raman light to be modulated.

[0031] It should be noted that the signal generation module 10 is configured to generate a modulation signal containing a predetermined phase jump sequence and output it to the phase modulator 20. The frequency of the modulation signal matches the frequency difference between the two frequency components of the target Raman light. The phase modulator 20 is configured to load the phase change of the modulation signal onto the incident light to generate Raman light with rapid phase shear.

[0032] Understandably, the core function of the signal generation module 10 is to generate a precision electrical modulation signal containing a predetermined phase transition sequence. The phase transition sequence refers to a series of discrete phase value change instructions precisely arranged in time. Its transition speed, i.e., the response time of the phase switching, is significantly faster than the duration of the Raman pulse in the atomic interferometer, typically on the order of nanoseconds to microseconds, to ensure that one or more phase switching operations can be completed during the action of a single Raman pulse.

[0033] Understandably, the modulation signal is typically a radio frequency (RF) or microwave signal, whose frequency is configured to strictly match or lock with the frequency difference between the two frequency components of the target Raman light. This frequency difference corresponds to the transition frequency between the two hyperfine levels of the atom's ground state. The frequency difference between the two frequency components of the target Raman light refers to the frequency difference of the Raman light required by the interferometer. For example, for rubidium-87 atoms, it is approximately 6.834 GHz. "Predetermined" means that the sequence is pre-calculated or designed according to the specific operating mode of the atomic interferometer, such as π / 2 pulse, π pulse, vibration noise suppression requirements, or robustness optimization algorithms. It can be generated by a field-programmable gate array (FPGA), a direct digital frequency synthesizer (DDS), or a microprocessor with storage circuitry, but is not limited to this method. Understandably, a modulation signal containing a predetermined phase transition sequence refers to an RF or microwave drive signal with a specific time-domain waveform. Its core characteristic is that its instantaneous phase value can discretely transition according to a pre-defined, non-periodic time-phase relationship function. This transition is deterministic, not random, and aims to actively shape the evolution path of the atomic wavefunction. The amplitude of the signal is typically kept constant to ensure that when applied to the phase modulator 20, the electro-optic effect primarily causes a linear change in the refractive index, thereby producing pure phase modulation and minimizing unnecessary additional intensity modulation.

[0034] It is understood that, in this embodiment, the phase modulator 20 is specifically defined as a pure phase modulator based on the electro-optic effect. This device directly, continuously, and in situ changes the phase of Raman light passing through its optical waveguide or nonlinear optical crystal by means of an electrical modulation signal applied to it, without changing its propagation direction or spatial mode, and without relying on diffraction or beam splitting mechanisms to achieve phase state switching. In other words, the phase modulator 20 is a device capable of linearly and rapidly converting the phase change of an input electrical signal into a phase change of the output light wave.

[0035] Understandably, loading the phase change of the modulation signal onto Raman light means that after receiving the modulation signal from the signal generation module 10 and the original laser light from the incident light source, the modulator's internal optical properties, such as the refractive index, change rapidly under the control of the modulation signal voltage. This causes the transmitted or reflected incident light carrier to produce an instantaneous phase shift synchronized with the modulation signal, generating Raman light with a rapidly changing phase. For example, an electro-optic phase modulator converts the original, phase-continuous Raman light into Raman light with a rapidly changing phase sequence in this way. This beam is then used to interact with atoms, thereby achieving active noise suppression, vibration compensation, or enhanced operational robustness in an atomic interferometer.

[0036] It should be specifically noted that this embodiment explicitly excludes acousto-optic modulators, electro-optic intensity modulators, etc., as implementations of the phase modulator 20. Acousto-optic modulators rely on periodic refractive index changes caused by sound waves to form a moving grating; essentially, they split light through diffraction. Their phase control is indirect and coupled with the diffraction angle, making it impossible to achieve the direct, rapid, and programmable phase transitions of the same propagating beam required by this scheme. Although electro-optic Mach-Zehnder intensity modulators are based on the electro-optic effect, they convert phase changes into intensity changes through interference principles. The phase of the output light is not a direct linear mapping of the input electrical signal, which also does not meet the pure phase modulation requirement of this scheme.

[0037] Further, please refer to Figure 2 , Figure 2 This is a structural block diagram of the signal generation module provided in an embodiment of this application. This application further defines the signal generation module 10.

[0038] In this embodiment, the signal generation module 10 includes: a phase transition generation unit 11, a first mixing unit 12, and a second mixing unit 13.

[0039] It should be noted that the output terminal of the phase transition generation unit 11 is connected to the input terminal of the first mixing unit 12; the output terminal of the first mixing unit 12 is connected to the input terminal of the second mixing unit 13; and the output terminal of the second mixing unit 13 is connected to the first input terminal of the phase modulator 20.

[0040] Understandably, this is a multi-stage up-conversion circuit architecture used to generate high-frequency modulated signals with precise frequency and rapidly programmable phase transitions. Specifically, the output of the phase transition generation unit 11 is connected to the input of the first mixer unit 12 and is used to transmit the initial phase transition signal; the output of the first mixer unit 12 is connected to the input of the second mixer unit 13 and is used to transmit the intermediate frequency phase transition signal after one up-conversion and filtering; the output of the second mixer unit 13 serves as the final output of the signal generation module 10 and is connected to the RF input of the phase modulator 20.

[0041] It should be noted that the phase transition generation unit 11 is configured to output a phase transition signal to the first mixing unit 12 based on a predetermined phase transition sequence.

[0042] Understandably, the phase transition generation unit 11 is the source of the core phase control command. It is configured to output a relatively low-frequency phase transition signal based on a predetermined phase transition sequence. Here, "based on" means that the unit generates the corresponding control waveform based on a digital sequence stored in internal memory, such as ROM or RAM, or based on external commands received in real time. The phase transition signal specifically refers to a carrier frequency, for example, a relatively low radio frequency signal in the tens to hundreds of MHz range, whose phase value can change rapidly and discretely at specific moments according to the command. One specific implementation of this unit is a direct digital frequency synthesizer, which internally includes a phase accumulator, a phase-to-amplitude converter, and a digital-to-analog converter. By programming and changing its phase control word, a precise, instantaneously phase-changing analog signal can be generated at the output.

[0043] It should be noted that the first mixing unit 12 is configured to mix and filter the phase-jumping signal with a preset fixed-frequency sine source to generate an intermediate-frequency phase-jumping signal and output it to the second mixing unit 13; the second mixing unit 13 is configured to mix and filter the intermediate-frequency phase-jumping signal with the first high-frequency microwave source 131 to generate a high-frequency phase-jumping signal as a modulation signal and output it to the phase modulator 20.

[0044] Understandably, the first mixing unit 12 performs the first frequency shift and signal purification. It is configured to mix the phase-jump signal from the phase-jump generation unit 11 with a reference signal from a preset fixed-frequency sinusoidal source, such as a highly stable crystal oscillator or a phase-locked loop frequency synthesizer. Mixing is a nonlinear frequency transformation process, typically implemented by a mixer, such as a double-balanced mixer, whose output contains the sum and difference frequency components of the two input signals. Subsequently, filters within the unit, such as bandpass or low-pass filters, selectively filter the mixer output to extract the desired frequency component, typically one of the sum or difference frequency, thereby generating a phase-jump signal whose frequency is boosted to an intermediate frequency, for example, in the range of hundreds of MHz to several GHz. This step shifts the low-frequency phase-jump signal to a more suitable intermediate frequency and initially suppresses unwanted harmonics or spurious components from the phase-jump generation unit.

[0045] Understandably, the second mixer unit 13 performs a final frequency shift to match the atomic resonance frequency. It is configured to perform a second mixing and filtering of the intermediate frequency phase-change signal output from the first mixer unit 12 with a signal from a first high-frequency microwave source 131, for example, a signal from a high-performance microwave synthesizer operating in the several GHz band. The frequency of the first high-frequency microwave source 131 is precisely set so that, after this mixing and subsequent filtering, the frequency of the final output high-frequency phase-change signal is precisely matched to the ground-state hyperfine level transition frequency of the target atom, such as rubidium-87, which is approximately 6.834 GHz. This final signal then serves as the modulation signal to drive the phase modulator 20.

[0046] Understandably, this two-stage mixing architecture achieves the precise upsampling of the signal frequency to the required microwave band while maintaining the high resolution and flexibility of the original low-frequency phase transition sequence, and is beneficial for optimizing the phase noise performance and frequency purity of the entire link.

[0047] In summary, this application provides an implementation method for the above embodiments. Please refer to... Figure 3 , Figure 3 This is a device selection and connection diagram for the signal generation module provided in the embodiments of this application.

[0048] Specifically, the phase transition generation unit 11 includes: a first waveform generator 111; the output terminal of the first waveform generator 111 is connected to the input terminal of the first mixer unit 12; the first waveform generator 111 is configured to generate a baseband phase modulation signal containing a predetermined phase transition sequence, as a phase transition signal output.

[0049] Understandably, a baseband phase-modulated signal refers to an initial radio frequency signal carrying a predetermined phase-change sequence that has a relatively low frequency and has not undergone up-conversion processing. Its baseband characteristic is that the signal's frequency is significantly lower than the final required high-frequency microwave signal frequency. Unlike amplitude or frequency modulation, its carrier amplitude is typically constant, while the carrier's phase value undergoes discrete, non-periodic transitions at specific times according to a predetermined sequence.

[0050] Specifically, the first mixing unit 12 includes: a second waveform generator 121, a first mixer 122, and a first filter 123; the first input terminal of the first mixer 122 is connected to the output terminal of the phase transition generation unit 11, and the second input terminal of the first mixer 122 is connected to the output terminal of the second waveform generator 121; the output terminal of the first mixer 122 is connected to the input terminal of the first filter 123; the output terminal of the first filter 123 is connected to the input terminal of the second mixing unit 13; the second waveform generator 121 is configured to generate a sine wave signal of a fixed frequency as a preset fixed frequency sine source.

[0051] Understandably, the second waveform generator 121 is configured as a reference signal source with high frequency stability and low phase noise to generate a fixed-frequency sine wave signal, i.e., the aforementioned preset fixed-frequency sine source. The fixed frequency refers to the fact that its output frequency value remains constant during system operation, typically set to an intermediate frequency value that facilitates subsequent filtering, such as 100 MHz or 400 MHz. A sine wave implies that the output waveform is a pure single-frequency signal, with its harmonics and spurious components suppressed to a low level. A typical implementation of this component is a crystal oscillator or a high-precision frequency synthesizer based on phase-locked loop technology, the core of which is to provide a local oscillator signal with accurate frequency and low phase noise to ensure that the additional phase noise introduced during the up-conversion process is minimized.

[0052] Understandably, the first mixer 122 is a nonlinear electronic device that performs the core frequency conversion operation of mixing. It is configured to receive signals from two input terminals and, utilizing its nonlinear characteristics, generate an output signal containing the sum-frequency component, difference-frequency component, and their respective higher-order harmonic combination components of the two input signal frequencies. In this application, its function is to mix a lower-frequency signal, such as a baseband signal, carrying a phase-change sequence from the phase-change generation unit 11, with a fixed-frequency sine wave from the second waveform generator 121, thereby generating a new signal with a boosted frequency that still carries the original phase-change information. This device typically uses a double-balanced mixer to achieve efficient mixing while effectively suppressing signal leakage and intermodulation products between the local oscillator port and the RF port.

[0053] Understandably, the first filter 123 is a frequency-selective network that performs filtering operations. It is configured to filter the broadband signal output from the first mixer 122, selectively allowing the desired frequency component, typically one of the sum or difference frequency components selected according to frequency planning, to pass through, and significantly attenuating other unwanted frequency components, including but not limited to: the original input signal frequency, another unselected mixing product such as the difference frequency, harmonics generated during mixing, and local oscillator leakage signals. This step is crucial for generating a clean intermediate frequency phase-jump signal. A common implementation of this device is a bandpass filter, whose center frequency is designed to be equal to the frequency of the desired component, and whose bandwidth is determined according to the signal spectrum and system requirements. This can be implemented using lumped-parameter elements such as inductors, capacitors, dielectric resonators, surface acoustic wave devices, etc.

[0054] Specifically, the second mixing unit 13 includes: a first high-frequency microwave source 131, a second mixer 132, and a second filter 133; the first input terminal of the second mixer 132 is connected to the output terminal of the first mixing unit 12, and the second input terminal of the second mixer 132 is connected to the output terminal of the first high-frequency microwave source 131; the output terminal of the second mixer 132 is connected to the input terminal of the second filter 133; the output terminal of the second filter 133 is the first input terminal of the phase modulator 20; the first high-frequency microwave source 131 is configured to generate a high-frequency microwave signal with a frequency equal to the frequency difference between the two frequency components of Raman light.

[0055] Understandably, the first high-frequency microwave source 131 serves as the frequency reference and final frequency determination unit for the entire signal chain. It is configured to participate in mixing, causing the second mixer 133 to generate a high-frequency microwave signal with a frequency equal to the frequency difference between the two frequency components of the target Raman light. The frequency of this signal is precisely set to be equal to, or corresponds to through a fixed harmonic / division relationship, the transition frequency between the two hyperfine levels of the ground state of the rubidium-87 atom, i.e., the frequency difference between the two frequency components of the target Raman light, for example, 6.834 GHz. Here, "high frequency" specifically refers to the microwave band, typically above 1 GHz. As a standalone signal generator, a key implementation of this component is a microwave frequency synthesizer, which is typically based on a highly stable reference clock, such as a 10 MHz crystal oscillator or atomic clock, and generates the required microwave frequency using phase-locked loop (PLL) technology. It must possess extremely low single-sideband phase noise, as this phase noise is directly transmitted to the modulated Raman light, affecting atomic coherence.

[0056] Understandably, the second mixer 132 is the core frequency conversion device of this unit. It is configured to perform a second nonlinear mixing operation, mixing the intermediate frequency (IF) signal from the first mixer unit 12, which has been modulated with a phase-jump sequence, with the clean high-frequency microwave local oscillator signal from the first high-frequency microwave source 131. Its output will contain the sum frequency, difference frequency, and other intermodulation products of the two input signals. In this application, the difference frequency component is typically chosen to ensure that the final signal frequency accurately falls on the atomic resonance frequency. This device is typically a double-balanced mixer operating in the microwave band to provide good port isolation while achieving efficient frequency conversion and suppressing leakage of the local oscillator signal to the IF port and reverse crosstalk.

[0057] Understandably, the second filter 133 is a spectral shaping and purification device for the final output signal. It is configured to selectively filter the broadband signal output from the second mixer 132. Its core function is to extract the desired high-frequency components, such as the aforementioned sum-frequency components, from the numerous frequency components generated by mixing with a high suppression ratio, and to suppress all other unwanted components, including but not limited to: residual intermediate frequency signals, local oscillator leakage, difference frequency components, and harmonics and spurious signals generated by mixing. Since the operating frequency is already in the microwave band, a typical implementation of this device is a dielectric resonator filter or cavity filter, which can provide narrow bandwidth, low insertion loss, and high out-of-band rejection at the center frequency, such as 6.834 GHz, ensuring that the modulated signal fed into the phase modulator 20 has extremely high spectral purity.

[0058] In one feasible implementation, both the first and second waveform generators are arbitrary waveform generators. The first waveform generator is a Keysight 33600A, used to generate a 40MHz phase-change signal; the second waveform generator is a Keysight 33500B, used to generate a 25MHz sine wave signal. The two signals are mixed by a first mixer to obtain a sum frequency of 65MHz, and then filtered by a 65MHz bandpass filter (the first filter) to produce a clean 65MHz phase-change signal.

[0059] Next, the 65MHz phase-change signal is mixed with a 6.9GHz high-frequency microwave source (second mixer) to obtain a phase-change signal with a difference frequency of 6.834GHz (and Rb). 87 (The atoms' D2 transition lines are matched), and then a 6.834 GHz bandpass filter (the second filter) is used to obtain a pure 6.834 GHz phase-change signal, which is the modulation signal. The 6.834 GHz phase-change signal is then input into an electro-optic phase modulator, thereby outputting 6.834 GHz phase-change Raman light, which enters the optical path through an optical fiber coupler.

[0060] In this embodiment, by employing a technique that integrates a signal generation module and a phase modulator, the signal generation module first generates a modulation signal whose frequency matches the frequency difference between the two frequency components of the target Raman light and whose phase changes rapidly. This allows the modulation signal to be precisely aligned with the first-order sideband of the Raman light, thus enabling subsequent direct overall modulation of the Raman light. Next, the phase modulator loads the phase change of the modulation signal, containing a predetermined phase jump sequence, onto the incident light, generating Raman light with a rapidly changing phase. Since the phase modulator can simultaneously transmit the two frequency components within a single device, this not only eliminates the additional phase noise introduced by optical path separation and independent control during separate modulation but also simplifies the system structure through integrated design.

[0061] Ultimately, compared with existing technologies, this application achieves rapid phase shearing of Raman light, which improves modulation efficiency and stability while reducing system complexity and phase error, thereby solving the problems of complex optical paths and increased noise in traditional methods.

[0062] Furthermore, based on the above embodiments, this application introduces new modules to achieve more comprehensive functionality. Please refer to... Figure 4 , Figure 4 This is the second structural block diagram of the Raman optical phase fast shearing device provided in the embodiments of this application.

[0063] In this embodiment, the Raman light phase fast shear device further includes: a detection module 30; the input end of the detection module 30 is connected to the output end of the phase modulator 20; the detection module 30 is configured to collect the phase information of the modulated Raman light to verify the modulation result.

[0064] Understandably, the Raman phase fast switching device further integrates a detection module 30 into the modulation link formed by the signal generation module 10 and the phase modulator 20, thus forming a closed-loop system with real-time monitoring and verification functions. Specifically, the input of the detection module 30 is connected to the output of the phase modulator 20 via an optical path, for example, by extracting a small portion of the optical power through a beam splitter, to receive the modulated Raman light. Its core function is to collect and analyze the phase change information carried in the modulated Raman light in real time, and compare it with a preset phase transition sequence, thereby verifying whether the phase modulator 20 has accurately performed the expected phase modulation operation.

[0065] Specifically, specific implementation methods are shown below; please refer to [link / reference]. Figure 5 . Figure 5 This is a device selection and connection diagram for the detection module provided in the embodiments of this application.

[0066] In this embodiment, the detection module 30 includes: an optocoupler 301, a photodetector 302, a second high-frequency microwave source 303, a third mixer 304, a third filter 305, and an oscilloscope 306.

[0067] It should be noted that the input terminal of the optocoupler 301 is coupled to the output optical path of the phase modulator 20; the output terminal of the optocoupler 301 is connected to the optical input port of the photodetector 302; the electrical output port of the photodetector 302 is connected to the first input terminal of the third mixer 304; the output terminal of the second high-frequency microwave source 303 is connected to the second input terminal of the third mixer 304; the output terminal of the third mixer 304 is connected to the input terminal of the third filter 305; and the output terminal of the third filter 305 is connected to the signal input channel of the oscilloscope 306.

[0068] Understandably, the detection module 30 employs a hardware architecture based on the heterodyne detection principle to extract and verify the phase information of the modulated Raman light. The components are connected sequentially according to the signal flow, forming a complete photoelectric conversion and signal down-conversion path.

[0069] Understandably, the optocoupler 301 is an optical device used to non-destructively extract a portion of the optical signal power. Its input is optically coupled to the output optical path of the phase modulator 20 via a fiber optic connector or spatial optical coupling to extract a small portion (e.g., 1% to 10%) of the phase-modulated Raman light as the detection sample light. Its output guides this portion of light to the photodetector 302. A typical implementation of this device is a fiber optic beam splitter; for fiber optic systems or beam splitters, for free-space optical paths, its core function is to provide an optical signal for detection without affecting the power of the main optical path. Alternative devices include optical circulators with similar functions or directly using optical plates with transmission and reflection beam splitting capabilities.

[0070] Understandably, the photodetector 302 is a photoelectric conversion device that linearly converts an optical signal into an electrical signal. Its optical input port receives the optical signal from the optocoupler 301, and its electrical output port outputs a corresponding first electrical signal. The frequency of this first electrical signal is the same as the microwave modulation frequency of the modulated Raman light, for example, approximately 6.834 GHz, and its phase change reflects the phase jump sequence loaded on the optical carrier. This device needs to have sufficient response bandwidth to cover the frequency components of the modulated signal, typically achieved using a high-speed photodiode, such as a PIN photodiode or an avalanche photodiode. Its detection function refers to its internal photoelectric effect converting the instantaneous change in incident light power into an instantaneous change in photocurrent.

[0071] Understandably, the second high-frequency microwave source 303 is a highly stable local oscillator. Its function is to enable the third mixer 304 to generate a high-purity continuous wave microwave signal with a frequency close to that of the microwave modulation signal under test after participating in the mixing process, serving as a reference signal for heterodyne detection. Its frequency setting must ensure that it can generate an intermediate frequency signal suitable for oscilloscope acquisition after mixing with the first electrical signal.

[0072] It should be noted that the third mixer 304 is configured to mix the first electrical signal detected by the photodetector 302 with the signal from the second high-frequency microwave source 303, and then filter it through the third filter 305 to generate an intermediate frequency or baseband signal that can be acquired and analyzed by the oscilloscope 306, so as to demodulate the loaded phase transition information. This will not be elaborated here.

[0073] In one specific implementation, a beam splitter is used in the optical path to separate 10% of the light and direct it to the photodetector. The output should be a 6.834 GHz phase-jump electrical signal (after passing through the optical path), which is the first electrical signal. This electrical signal is then mixed with a 6.9 GHz high-frequency microwave source (third mixer) to obtain a phase detection signal with a difference frequency of 65 MHz. This signal is then passed through a 65 MHz bandpass filter to obtain a clean 65 MHz detection signal. Finally, an oscilloscope (SIGLENT SDS1204X HD) is used to obtain the specific data of the detection signal. I / Q demodulation is then performed to obtain its phase information, and the error between the actual phase and the designed phase is calculated through programming.

[0074] In addition, this application also provides an embodiment of a Raman optical phase fast shearing method. Please refer to... Figure 6 , Figure 6 This is a schematic flowchart of the Raman optical phase fast shearing method provided in the embodiments of this application. It further verifies the feasibility of the above-described device.

[0075] In this embodiment, the Raman phase fast shearing method includes steps S10 to S30.

[0076] Step S10: Generate a phase transition signal based on a predetermined phase transition sequence.

[0077] Understandably, the details of how phase-jumping signals are generated will not be elaborated here. The following example will be used to illustrate the process. Taking a signal with a rapidly changing phase as an example... Phase change The form is as follows Figure 7 To further explain, see the illustration.

[0078] Specifically, Figure 7 This is a schematic diagram of phase change provided in an embodiment of this application. The first phase jump occurs at time t1, located at the position indicated by the red line, where the phase jump amount is... This specifically represents the meaning of phase jump.

[0079] In the signal calculation process here, the fast phase transition signal takes the form of: where , Phase change The specific values ​​are shown in Table 1 below, and are verified accordingly.

[0080] Table 1:

[0081] Understandably, this optimized pulse has 20 transition points besides the initial moment, with a total duration of 184.9306 seconds. .

[0082] Step S20: Based on the frequency difference between the two frequency components of the target Raman light, the phase-jumping signal is mixed to generate a modulation signal that matches the frequency difference between the two frequency components of the target Raman light and has a rapidly changing phase.

[0083] Understandably, the core purpose of step S20 is frequency conversion and matching. Through one or more stages of mixing, it precisely shifts a low-frequency electrical signal, which is easily generated and programmed and carries a phase-jump sequence, to a high-microwave frequency band that is exactly the same as the hyperfine level transition frequency of the target atom, such as rubidium-87. This is to ensure that the final electrically modulated signal resonates precisely with the quantum state of the atom, thereby effectively driving stimulated Raman transitions.

[0084] Step S30: Based on the modulation signal, a predetermined phase-switching sequence is loaded onto the incident light through a phase modulator to output Raman light with rapid phase switching.

[0085] Understandably, the core of step S30 lies in electro-optic conversion and pure phase loading. It utilizes the linear electro-optic effect of the electro-optic phase modulator to directly and linearly map the voltage change of the high-frequency microwave modulation signal generated in step S20 into the optical phase change of the Raman laser passing through the modulator. This process is continuous and non-dispersive, capable of replicating the discrete phase-change sequence in electrical circuitry into phase-change sequences in optical waves with high fidelity and high speed, thereby achieving rapid phase shearing.

[0086] Step S30 is followed by: coupling a first optical signal based on the rapidly phase-switching Raman light and outputting a first electrical signal through photoelectric conversion; mixing the first electrical signal to generate a second electrical signal with a reduced frequency; and demodulating the second electrical signal to obtain the phase information of the modulated Raman light.

[0087] Understandably, a portion of the optical signal is coupled out from the modulated Raman light and converted into an electrical signal of the same frequency by a high-speed photodetector. This high-frequency electrical signal is then mixed with a local oscillator signal to generate a lower-frequency, easier-to-process intermediate frequency (IF) or baseband signal. This process completely preserves the phase information of the original signal. By demodulating the down-frequency signal (e.g., digital I / Q demodulation), the actual phase transition sequence contained within it is extracted and compared with a preset sequence, thereby verifying the modulation accuracy. Further details are omitted here.

[0088] The verification results are as follows Figure 8 As shown, Figure 8 This is a schematic diagram of the results of the phase fast shear provided in the embodiments of this application.

[0089] Understandable, Figure 8 The upper part shows the actual and designed phase diagrams of the detected 65MHz signal after passing through the optical path. In the figure, the actual phase (blue solid line) and the designed phase (orange solid line) exhibit highly consistent step transitions on the time axis. At multiple transition moments, the actual phase can accurately and quickly track and reproduce the preset designed phase changes, indicating that the phase modulator has successfully loaded the predetermined phase transition sequence in the electrical modulation signal onto the optical carrier with high fidelity.

[0090] Understandable, Figure 8 The lower half shows the corresponding error curve. The error value was strictly confined to an extremely narrow band close to zero throughout the entire observation period, with no significant deviation or drift. This quantitatively demonstrates that the difference between the actual phase jump and the preset sequence is minimal, and the systematic error is effectively controlled.

[0091] In summary, the verification results fully demonstrate that the phase fast switching device provided in this application embodiment can accurately and reliably realize the predetermined phase jump sequence on the nanosecond scale. The high degree of matching between the actual phase and the designed phase provides a key technical guarantee for the atomic interferometer to achieve high-performance noise suppression and robust control.

[0092] Further, the process can be extended to demodulate the second electrical signal to obtain the phase information of the modulated Raman light, and may further include: comparing the phase information of the Raman light with the phase-switching phase with a predetermined phase-switching sequence to obtain the comparison result, and adjusting the predetermined phase-switching sequence based on the comparison result.

[0093] Understandably, the comparison can be performed by the data processing unit, which compares the demodulated actual phase sequence with the preset sequence, calculates and generates error indicators, such as phase difference or root mean square error. Sequence adjustment, based on this comparison result, involves the feedback control unit generating correction commands to dynamically correct subsequent predetermined phase jump sequences or their generation parameters. Specific adjustment methods may include pre-compensating for static phase deviations, performing timing calibration for transient jump processes, or optimizing waveform parameters to improve overall fidelity. The specific implementation of the unit is not limited.

[0094] Understandably, the introduction of a closed-loop mechanism can continuously compensate for long-term errors caused by factors such as device drift and nonlinearity, thereby ensuring the long-term output accuracy and stability of the phase fast shear device and providing a guarantee for the high reliability of the atomic interferometer.

[0095] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0096] Furthermore, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0097] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A Raman optical phase fast shearing device, characterized in that, include: Signal generation module and phase modulator; The output of the signal generation module is connected to the first input of the phase modulator; the second input of the phase modulator is connected to the output of the incident light source. The signal generation module is configured to generate a modulated signal containing a predetermined phase jump sequence and output it to the phase modulator, wherein the frequency of the modulated signal matches the frequency difference between the two frequency components of the target Raman light; The phase modulator is configured to load the phase change of the modulation signal onto the incident light to generate Raman light with rapid phase shear.

2. The Raman optical phase fast shearing device as described in claim 1, characterized in that, The signal generation module includes: a phase transition generation unit, a first mixing unit, and a second mixing unit; The output of the phase transition generation unit is connected to the input of the first mixer unit; the output of the first mixer unit is connected to the input of the second mixer unit; the output of the second mixer unit is connected to the first input of the phase modulator. The phase transition generation unit is configured to output a phase transition signal to the first mixing unit based on a predetermined phase transition sequence; The first mixing unit is configured to mix and filter the phase-jump signal with a preset fixed-frequency sine source to generate an intermediate-frequency phase-jump signal and output it to the second mixing unit; The second mixing unit is configured to mix and filter the intermediate frequency phase-jump signal with the first high-frequency microwave source to generate a high-frequency phase-jump signal as a modulation signal and output it to the phase modulator.

3. The Raman optical phase fast shearing device as described in claim 2, characterized in that, The phase transition generation unit includes: a first waveform generator; The output terminal of the first waveform generator is connected to the input terminal of the first mixer unit; The first waveform generator is configured to generate a baseband phase modulation signal containing the predetermined phase transition sequence, as the phase transition signal output.

4. The Raman optical phase fast shearing device as described in claim 2, characterized in that, The first mixing unit includes: a second waveform generator, a first mixer, and a first filter; The first input terminal of the first mixer is connected to the output terminal of the phase transition generation unit, and the second input terminal of the first mixer is connected to the output terminal of the second waveform generator; the output terminal of the first mixer is connected to the input terminal of the first filter; the output terminal of the first filter is connected to the input terminal of the second mixer unit. The second waveform generator is configured to generate a sine wave signal of a fixed frequency as the preset fixed frequency sine source.

5. The Raman optical phase fast shearing device as described in claim 2, characterized in that, The second mixing unit includes: a first high-frequency microwave source, a second mixer, and a second filter; The first input terminal of the second mixer is connected to the output terminal of the first mixer unit, and the second input terminal of the second mixer is connected to the output terminal of the first high-frequency microwave source; the output terminal of the second mixer is connected to the input terminal of the second filter; the output terminal of the second filter is connected to the first input terminal of the phase modulator. The first high-frequency microwave source is configured to participate in the mixing process so that the second mixer generates a high-frequency microwave signal with a frequency equal to the frequency difference between the two frequency components of the target Raman light.

6. The Raman optical phase fast shearing device as described in claim 1, characterized in that, The Raman optical phase fast shear device further includes: a detection module; The input terminal of the detection module is connected to the output terminal of the phase modulator; The detection module is configured to acquire the phase information of the modulated Raman light to verify the modulation result.

7. The Raman optical phase fast shearing device as described in claim 6, characterized in that, The detection module includes: an optocoupler, a photodetector, a second high-frequency microwave source, a third mixer, a third filter, and an oscilloscope; The input terminal of the optocoupler is coupled to the output optical path of the phase modulator; the output terminal of the optocoupler is connected to the optical input port of the photodetector; the electrical output port of the photodetector is connected to the first input terminal of the third mixer; the output terminal of the second high-frequency microwave source is connected to the second input terminal of the third mixer; the output terminal of the third mixer is connected to the input terminal of the third filter; the output terminal of the third filter is connected to the signal input channel of the oscilloscope. The third mixer is configured to mix the first electrical signal detected by the photodetector with the signal from the second high-frequency microwave source to generate an intermediate frequency signal that can be acquired and analyzed by an oscilloscope, so as to demodulate the loaded phase transition information.

8. A method for rapid phase shearing in Raman spectroscopy, characterized in that, include: Generate a phase-jumping signal based on a predetermined phase-jumping sequence; Based on the frequency difference between the two frequency components of the target Raman light, the phase-jumping signal is mixed to generate a modulation signal that matches the frequency difference between the two frequency components of the target Raman light and has a rapidly changing phase. Based on the modulation signal, the predetermined phase-switching sequence is loaded onto the incident light through a phase modulator to output Raman light with rapid phase shearing.

9. The Raman optical phase fast shearing method as described in claim 8, characterized in that, Based on the modulation signal, the predetermined phase-switching sequence is loaded onto the incident light via a phase modulator to output Raman light with rapidly changing phase, followed by: Based on the Raman light with rapid phase shear, a first optical signal is generated by coupling and then output as a first electrical signal after photoelectric conversion. The first electrical signal is mixed to generate a second electrical signal with a lower frequency. Demodulate the second electrical signal to obtain the phase information of the modulated Raman light.

10. The Raman optical phase fast shearing method as described in claim 9, characterized in that, Demodulating the second electrical signal to obtain the phase information of the modulated Raman light, the process further includes: The phase information of the Raman light with the rapid phase shear is compared with the predetermined phase jump sequence to obtain the comparison result, and the predetermined phase jump sequence is adjusted based on the comparison result.

Images