[论文解读] Towards Ultrafast Gyroscopes Employing Real-time Intensity and Spectral Domain Measurements of Ultrashort Pulses

Maria Chernysheva, Srikanth Sugavanam+1 more|arXiv (Cornell University)|Mar 7, 2019

Geophysics and Sensor Technology参考文献 49被引用 7

一句话总结

该论文提出了一种新型超高速陀螺仪，通过实时测量双向锁模光纤激光器中反向传播的超短脉冲在空间-时间域和光谱域的特性，实现了比商用系统快两个数量级的陀螺仪读出速率，旋转分辨率达125–384 μrad·s⁻¹，且未观察到死区效应。

ABSTRACT

Active ring laser gyroscopes (RLG) operating on the principle of the optical Sagnac effect are preferred instruments for a range of applications, such as inertial guidance systems, seismology, and geodesy, that require both high bias stability and high angular velocity resolutions. Operating at such accuracy levels demands special precautions like dithering or multi-mode operation to eliminate frequency lock-in or similar effects introduced due to synchronisation of counter-propagating channels. Recently proposed bidirectional ultrafast fibre lasers can circumvent the limitations of continuous wave RLGs. However, their performance is limited due to the nature of the highly-averaged interrogation of the Sagnac effect. In general, the performance of current optical gyroscopes relies on the available measurement methods used for extracting the signal. Here, by changing the paradigm of traditional measurement and applying spatio-temporal intensity processing, we demonstrate that the bidirectional ultrafast laser can be transformed to an ultrafast gyroscope with acquisition rates of the order of the laser repetition rate, making them at least two orders of magnitude faster than commercially deployed versions. We also show the proof-of-principle for dead-band-free round trip time-resolved spectral domain measurements using the Dispersive Fourier Transform, further enhancing the gyroscopic sensitivity. Our results reveal the high potential of application of novel methods of signal measurements in mid-sized ultrafast fibre laser gyroscopes to achieve performances that are currently available only with large-scale RLGs.

研究动机与目标

• 克服传统光学陀螺仪因慢速、平均化的Sagnac效应探测方法导致的带宽和死区限制。
• 证明在双向超快光纤激光器中实时、高带宽测量超短脉冲可显著提升旋转传感的速度与灵敏度。
• 通过利用固有稳定的超快激光动力学与先进信号处理，消除对主动稳定或抖动控制的需求。
• 通过紧凑、全光纤配置验证超快陀螺仪的可行性，无需大规模基础设施。

提出的方法

• 采用双向锁模光纤激光器产生反向传播的超短孤子脉冲，用于Sagnac效应探测。
• 利用实时空间-时间动力学成像技术，实现往返时间分辨率下的脉冲漂移解析，可直接观测由旋转引起的时序漂移。
• 应用色散傅里叶变换（DFT）进行时间分辨光谱分析，实现载波包络偏移噪声抑制并提升灵敏度。
• 通过在强度域与光谱域中分析射频拍频信号，测量反向传播脉冲间的差分相位移。
• 利用高带宽探测器与实时示波器，捕获重复频率达激光基频的脉冲动力学。
• 通过依赖超快激光的固有稳定性（抖动<0.8 ps）与短积分时间，避免主动稳定或热隔离。

实验结果

研究问题

• RQ1 实时空间-时间域中反向传播超短脉冲的动力学是否能实现比传统平均方法更快、更灵敏的旋转传感？
• RQ2 色散傅里叶变换是否能实现在超快光纤激光器中Sagnac效应的无死区、高分辨率光谱测量？
• RQ3 紧凑、全光纤的超快激光配置在无主动稳定条件下，其性能在多大程度上可与大规模环形激光陀螺仪相媲美？
• RQ4 在旋转腔体中，脉冲相互作用动力学如何偏离线性Sagnac行为？该现象是否可建立模型？

主要发现

• 空间-时间动力学方法在10,000次往返中实现了384 μrad·s⁻¹的旋转分辨率，相较于商用系统读出速率提升两个数量级。
• 基于DFT的光谱方法在5,000次往返中实现了125 μrad·s⁻¹的旋转分辨率，证明其在无需主动稳定条件下的高灵敏度。
• 在整个测试的旋转速度范围内均未观察到死区效应，表明对频率闭锁具有强鲁棒性。
• 系统在无主动稳定或热隔离条件下运行，凸显了超快激光的内在稳定性及测量技术的鲁棒性。
• 结果表明，通过增加往返次数或扩大腔体尺寸，性能可提升一个以上数量级。
• 在更长腔体中观察到的偏离线性Sagnac行为现象，表明存在复杂的非局域脉冲相互作用，需在未来建立模型。