CN-122000785-A - Long-time laser frequency stabilization system based on-chip optical reference microcavity

CN122000785ACN 122000785 ACN122000785 ACN 122000785ACN-122000785-A

Abstract

The invention relates to a laser frequency stabilization technology, which provides a long-time laser frequency stabilization system based on an on-chip optical reference microcavity for solving the contradiction between the chip formation and the long-term frequency stabilization of the on-chip frequency stabilization technology, and comprises two lasers and the on-chip optical reference microcavity; the system comprises two frequency locking modules, a dual-mode beat frequency measurement and control module, an intracavity temperature slow feedback control loop and a temperature slow feedback control loop, wherein the two frequency locking modules are used for respectively locking two lasers to two different modes of an on-chip optical reference microcavity, the dual-mode beat frequency measurement and control module is used for measuring dual-mode frequency difference between the two different modes locked to the on-chip optical reference microcavity in real time, the intracavity temperature slow feedback control loop is used for generating a temperature fine control feedback signal based on the dual-mode frequency difference, and the fine temperature of the on-chip optical reference microcavity is regulated according to the temperature fine control feedback signal so as to compensate optical cavity length change caused by a thermo-optical effect and a thermal expansion effect, so that the resonant frequency of the on-chip optical reference microcavity is stabilized, the long-term drift of the optical frequency of the on-chip lasers is reduced, and the long-time frequency stability of single-frequency output of the lasers is improved.

Inventors

WANG GUOCHAO
YANG JUN
ZHU LINGXIAO
YAN SHUHUA
YANG MINGYUE
PENG MINGLIANG

Assignees

中国人民解放军国防科技大学

Dates

Publication Date: 20260508
Application Date: 20260408

Claims (12)

1. The long-time laser frequency stabilization system based on the on-chip optical reference microcavity is characterized by comprising: The two lasers are respectively a first laser and a second laser; an on-chip optical reference microcavity for providing frequency reference; the two frequency locking modules are respectively a first frequency locking module and a second frequency locking module and are used for locking the two lasers to two different modes of the on-chip optical reference microcavity respectively; the dual-mode beat frequency measurement and control module is used for measuring the dual-mode frequency difference between two different modes locked to the on-chip optical reference microcavity in real time; And the intra-cavity temperature slow feedback control loop is used for generating a temperature fine control feedback signal based on the dual-mode frequency difference, and finely adjusting the intra-cavity temperature of the on-chip optical reference microcavity according to the temperature fine control feedback signal so as to compensate the optical cavity length change caused by the thermo-optic effect and the thermal expansion effect, thereby stabilizing the resonance frequency of the on-chip optical reference microcavity and enabling the laser locked by the two frequency locking modules to obtain long-time frequency stability.
2. The long-time laser frequency stabilization system based on the on-chip optical reference microcavity according to claim 1, further comprising a microcavity temperature coarse tuning control module for adjusting the operating environment temperature of the on-chip optical reference microcavity to be within a target range, and realizing coarse tuning of the resonant frequency of the on-chip optical reference microcavity.
3. The long-time laser frequency stabilization system based on the on-chip optical reference microcavity according to claim 1 or 2, further comprising an arbitrary laser frequency locking module for locking an arbitrary output wavelength laser to the on-chip optical reference microcavity after long-time frequency stabilization to realize multi-wavelength frequency stabilization laser output.
4. A long-term laser frequency stabilization system based on an on-chip optical reference microcavity according to claim 3, characterized in that any laser frequency locking module comprises at least one any laser, each any laser corresponds to one third frequency locking module respectively, each any laser is locked to the on-chip optical reference microcavity by the corresponding third frequency locking module, and frequency-stabilized laser is output.
5. The long-term laser frequency stabilization system based on an on-chip optical reference microcavity of claim 1,2 or 4, wherein the two different modes are selected based on selecting a pair of different modes in a free spectral range, and the frequency difference between the two different modes is less than 10GHz.
6. The optical reference microcavity-based long-time laser frequency stabilization system of claim 5, characterized in that at least one parameter of mode type, order, polarization of the two different modes is different.
7. The long-time laser frequency stabilization system based on the on-chip optical reference microcavity according to claim 1, 2, 4 or 6, wherein the first laser and the second laser are on-chip lasers, and the frequency locking module is one of a laser locking module based on a PDH frequency stabilization technology, a laser locking module based on a tilt locking, a laser locking module based on an edge locking, a phase-discrimination locking module based on a phase-locked amplifier, and a laser locking module based on a self-injection locking.
8. The long-time laser frequency stabilization system based on the on-chip optical reference microcavity of claim 7, wherein the frequency locking module is a laser locking module based on a PDH frequency stabilization technology and comprises an electro-optic phase modulator, a polarization controller, a circulator, a photoelectric detector and a servo controller; the electro-optic phase modulator is used for generating modulation sidebands; The polarization controller is used for controlling the polarization state of laser; the circulator is used for guiding laser to enter and output an optical reference microcavity on the chip; the photoelectric detector is used for monitoring an optical reference microcavity output light field on the chip, converting the optical reference microcavity output light field into an electric signal and outputting the electric signal to the controller; And the servo controller is used for carrying out frequency demodulation on the electric signal to obtain a direct current error signal proportional to the deviation of the resonant frequency of the laser and the reference microcavity, and feeding back and controlling the on-chip laser in real time to realize the locking of the laser frequency.
9. The long-term laser frequency stabilization system based on an on-chip optical reference microcavity of claim 1 or 2 or 4 or 6 or 8, characterized in that the intra-cavity temperature slow feedback control loop comprises a kalman filter, a slow feedback controller and an intra-cavity temperature actuator; the Kalman filter is used for carrying out filtering processing on the dual-mode frequency difference measured in real time and generating a real-time temperature deviation signal representing real temperature fluctuation of the optical reference microcavity on the chip; The slow feedback controller generates a control signal of the temperature executing element in the cavity according to the real-time temperature deviation signal, and adjusts the temperature of the optical reference microcavity on the chip through the temperature executing element in the cavity to compensate the ambient temperature disturbance of the optical reference microcavity on the chip, so that the dual-mode frequency difference is locked at a preset value, and the high-precision closed-loop control of the temperature of the optical reference microcavity on the chip is realized.
10. The long-term laser frequency stabilization system based on an on-chip optical reference microcavity of claim 9, wherein the slow feedback control loop employs low-frequency feedback control of the bandwidth on the order of Hz.
11. The long-term laser frequency stabilization system based on the on-chip optical reference microcavity according to claim 9, wherein the intra-cavity temperature actuator is a voltage-controlled adjustable attenuator, and the voltage-controlled adjustable attenuator is arranged on an optical path from the first on-chip laser or the second on-chip laser to the on-chip optical reference microcavity and is used for adjusting the laser light intensity input to the on-chip optical reference microcavity by the first on-chip laser or the second on-chip laser; The slow feedback controller generates a control voltage signal of the voltage-controlled adjustable attenuator according to the real-time temperature deviation signal, adjusts the attenuation of the voltage-controlled adjustable attenuator, changes the laser intensity of the optical reference microcavity input by the first on-chip laser or the second on-chip laser, and enables the dual-mode frequency difference to be locked at a preset value through the photo-thermal effect compensation of the ambient temperature disturbance of the optical reference microcavity on the chip, thereby realizing the accurate closed-loop control of the temperature of the optical reference microcavity on the chip.
12. The long-time laser frequency stabilization system based on the on-chip optical reference microcavity according to claim 1 or 2 or 4 or 6 or 8 or 10 or 11, characterized in that the dual-mode beat frequency measurement and control module comprises a beam combiner, a photoelectric detector and a frequency meter; the beam combiner is used for combining two laser beams with two different modes which are locked to the on-chip optical reference microcavity; the photoelectric detector is used for converting the optical signals after beam combination into electric signals; the frequency meter is used to measure a dual mode frequency difference between two different modes that have been locked to the on-chip optical reference microcavity.

Description

Long-time laser frequency stabilization system based on-chip optical reference microcavity Technical Field The invention mainly relates to the technical field of laser frequency stabilization, in particular to a long-time laser frequency stabilization system based on an on-chip optical reference microcavity. Background The high-stability laser light source is used as a core device for precise spectrum measurement, and has been widely applied in the fields of optical metering, spectroscopy, optical communication, quantum information and the like. Along with the development of integrated photon technology, miniaturization and chip formation of laser frequency stabilization technology become the basis and precondition for solving the application requirements of portability, low cost and low power consumption. The high stability frequency reference is the key to laser frequency stabilization technology. Conventional frequency references typically use atomic or molecular transition lines and optical resonators. The miniaturization and microminiaturization of the current frequency reference comprise an optical fiber cavity, a micromachined rubidium vapor cell, a vacuum gap miniature FP cavity, a whispering gallery resonant cavity and a waveguide integrated resonant cavity. But where only the waveguide integrated resonator has CMOS compatible capabilities, can be referred to as a chip-level optical reference. However, practical applications of waveguide-integrated resonators are limited by large thermo-optic coefficients, making them exceptionally sensitive to environmental disturbances, especially temperature drift, resulting in poor long-term frequency stability. In order to solve the problem of resonance frequency drift caused by environmental thermal fluctuation, some active control and material compensation and temperature measurement methods are proposed. However, these methods do not solve the problem well at present, and the long-term frequency stability level in the period exceeding 10000s only reaches 10 -8 orders of magnitude, and the accuracy level is not enough for the fields of atomic cooling, laser radar and the like. The integration level and the chip degree are not high, the existing mainstream technology is based on miniaturized reference cavities such as an optical fiber cavity, a micromachined rubidium steam battery, a vacuum gap miniature FP cavity, a whispering gallery resonant cavity and the like, the volume is large, and COMS compatibility and on-chip integration cannot be achieved at present. The long-term frequency stability is poor, the long-term frequency stability level of the existing frequency stabilizing technology based on the on-chip resonant cavity in the period exceeding 10000s only reaches 10 -8 orders of magnitude, and the application of the technology in the field of precise measurement is limited. The flexibility of the frequency reference is poor, the existing frequency reference with good long-term stability can only depend on the transition frequency of specific atoms or molecules, and the frequency value can not be flexibly adjusted. Disclosure of Invention Aiming at the problems existing in the prior art, the invention provides a long-time laser frequency stabilization system based on an on-chip optical reference microcavity, which solves the problem of thermal instability of the on-chip microcavity by dual-mode beat frequency locking and realizes the on-chip long-term frequency stabilization in order to solve the contradiction between 'chip formation' and 'long-term frequency stabilization' of the on-chip frequency stabilization technology. The invention provides the following technical scheme for realizing the purpose: The invention provides a long-time laser frequency stabilization system based on an on-chip optical reference microcavity, which comprises: The two lasers are respectively a first laser and a second laser; an on-chip optical reference microcavity for providing frequency reference; the two frequency locking modules are respectively a first frequency locking module and a second frequency locking module and are used for locking the two lasers to two different modes of the on-chip optical reference microcavity respectively; the dual-mode beat frequency measurement and control module is used for measuring the dual-mode frequency difference between two different modes locked to the on-chip optical reference microcavity in real time; And the temperature slow feedback control loop is used for generating a temperature fine control feedback signal based on the dual-mode frequency difference, and carrying out fine adjustment on the temperature in the optical reference microcavity on the chip according to the temperature fine control feedback signal so as to compensate the optical cavity length change caused by the thermo-optic effect and the thermal expansion effect, thereby stabilizing the resonance frequency of the optical reference microcavity on the chip and e