Author Affiliations
Abstract
1 College of Optical and Electronic Technology, China Jiliang University, Hangzhou 310018, China
2 Key Laboratory of Medical Electronics and Digital Health of Zhejiang Province, Jiaxing University, Jiaxing 314001, China
A simple quasi-distributed fiber sensing interrogation system based on random speckles is proposed for weak fiber Bragg gratings (WFBGs) in this work. Without using tunable lasers or spectrometers, a piece of multimode fiber is applied to interrogate the WFBGs relying on the wavelength sensitivity of speckles. Instead of the CCD sensor, an InGaAs quadrant detector serves as the receiver to capture the fast-changing speckle patterns. A supervised deep learning algorithm of the multilayer perceptron architecture is implemented to process speckle data and to interrogate temperature changes or dynamic strains. The proposed demodulation system is experimentally demonstrated for WFBGs with 0.1% reflectivity. The experimental results demonstrate that the new system is capable of measuring temperature change with an accuracy of 1°C and achieving dynamic frequency of 100 Hz. This speckle-based interrogation system paves a new way for distributed WFBGs sensing with a simple design.
weak fiber Bragg gratings random speckles deep learning time-division-multiplexing Chinese Optics Letters
2023, 21(12): 121601
同济大学 电子与信息工程学院 信息与通信工程系, 上海 201804
谐振式光纤陀螺（Resonator Fiber Optic Gyroscope, RFOG）的性能是多种误差和噪声共同作用的结果。分析了RFOG主要误差与噪声的产生机理, 建立了各误差与噪声的分析模型, 结合具体陀螺参数, 对误差和噪声的等效旋转速率进行了估算, 对抑制误差和噪声的有关措施进行了数值量化。以RFOG零偏稳定性0.1°/h需求为例, 为抑制背向散射噪声及背向反射误差, 相位调制移频时顺时针和逆时针光波的载波强度残留水平之积需高于112dB; 为抑制克尔效应, 顺时针和逆时针方向的光强差需控制在3.86nW以内; 地磁场方向不确定性引起的陀螺零偏稳定性约为0.7°/h。该工作为RFOG实验研究和工程设计提供了理论指导。
谐振式光纤陀螺 光纤环形谐振腔 误差与噪声 背向散射 resonant fiber optic gyroscope ring resonator error and noise backscattering
Author Affiliations
Abstract
1 College of Electronics and Information Engineering, Tongji University, Shanghai 201806, China
2 Shanghai Aerospace Control Technology Institute, Shanghai 201109, China
3 Shanghai Engineering Research Center of Inertia, Shanghai 201109, China
A resonator fiber optic gyro with the light time-division input and multiplexing output (TDM-RFOG) in the clockwise (CW) and counterclockwise (CCW) directions is proposed. The light time-division input in the CW and CCW directions can effectively suppress the backscattering induced noise. The TDM-RFOG is implemented with the 2 × 2 Mach–Zehnder interferometer (MZI) optical switch. The response time of the fiber ring resonator is analyzed, and it is demonstrated by experiments that light time-division input in the CW and CCW directions can reduce the backscattering induced noise. The suppression effectiveness of backscattering induced noise in the TDM-RFOG is determined by the extinction ratio of the optical switch, so a closed loop is designed to adjust the phase shift difference between the two arms of the MZI optical switch to control the extinction ratio. The method using two arms of the MZI optical switch with twin 90° polarization-axis rotated splices is proposed to make the extinction ratio along both slow and fast axes greater than ?70 dB.
resonator fiber optic gyroscope Mach–Zehnder interferometer backscattering induced noise Chinese Optics Letters
2020, 18(3): 030601
谐振型光纤陀螺(RFOG)因具有敏感光纤短和体积小等优点而备受关注。分析了激光线宽、光纤环形谐振腔(FRR)及检测技术对RFOG灵敏度的影响。依据RFOG信号检测方法, 推导了受光电检测器灵敏度限制的RFOG灵敏度公式, 并给出了考虑激光线宽和腔内偏振轴90°旋转的RFOG灵敏度修正公式。基于多光束干涉原理,分析了数字调相电压的误差和噪声对灵敏度的影响。仿真结果表明, 为获得高灵敏度, 针对不同的激光线宽应选取不同的FRR腔长, 偏振轴90°旋转熔接的两边长度差应为保偏光纤半拍长的奇数倍, 数字调相电压的噪声方均根值应小于0.22 V。该工作为高精度RFOG的设计提供了理论指导。
光纤光学 光纤陀螺 光纤环形谐振腔 灵敏度 激光线宽
海军工程大学理学院应用物理系, 湖北 武汉 430033
以红外成像光学系统为例, 运用矩阵光学追迹法, 对其产生的三种回波进行研究: “猫眼效应”; “近似猫眼效应”; “剩余反射效应”。研究结果表明: “猫眼效应”和“近似猫眼效应”产生的回波概率极低, 而“剩余反射效应”的回波相对较稳定, 回波概率较高。综合利用这三种反射回波, 将大大提高探测概率。
激光探测技术 红外成像光学系统 回波 光学追迹 laser detect technique infrared optical system reflection matrix optics
海军工程大学 理学院 应用物理系, 武汉 430033
阐述用激光主动探测的原理及实验技术。以红外光学系统为例，运用矩阵光学追迹法对光学系统中各镜片的回波强度、分布及影响因素作定性、定量分析，并用实验加以验证。研究结果表明，回波强度受探测距离、扫描激光光束的入射角等因素影响非常大。例如，在主动扫描装置与被探测观瞄仪器相距约1000m、扫描光束的入射角从0rad增大到0.18rad时，光学系统的前两块透镜表面所产生回波能量与发射脉冲能量之比由理想条件下的28.4%下降到0%。
激光技术 矩阵光学追迹法 剩余反射 实验验证 laser techniques ray tracing specular reflection experimental examination
Author Affiliations
Abstract
Nonlinear absorption of monolayer graphene suspension is studied in the wavelength of 800 nm using Z-scan method with 50-fs pulses. Nonlinear absorption property of graphene suspension at different excitation intensities is compared. Large reverse saturable absorptions are found and believed to arise from twophoton absorption.
190.4400 Nonlinear optics, materials 190.4180 Multiphoton processes 190.7110 Ultrafast nonlinear optics Chinese Optics Letters
2012, 10(7): 071901
海军工程大学理学院应用物理系，湖北 武汉 430033
为研究用激光主动扫描法侦察远方飞航导弹来袭方位的原理及实验技术，以红外点源导引头光学系统为例，运用矩阵光学追迹法对影响“猫眼效应”回波强度的因素作定量分析，并用实验进行验证。研究结果表明: 回波强度受扫描激光光束的入射角影响较大，导引头光路中摄像管靶面离焦、倾斜和光学镜头相对孔径等因素对回波强度也有一定影响。
激光探测技术 红外点源导引头光学系统 反射 “猫眼”效应 矩阵光学 laser detect technique infrared seeker optical system reflection "Cat's eye" effect matrix optics
西安电子科技大学技术物理学院, 陕西 西安 710071
基于光折变自弯曲相继四波混频多作用区理论，利用类电子学观点建立了多作用区互抽运相位共轭效应(MPPC)输出特性的理论计算模型。根据此模型数值模拟了作用区之间振幅传输系数对MPPC阈值耦合强度以及反射率的影响,发现振幅传输系数越低，MPPC所需要的阈值耦合强度越高，且在相同的耦合强度下，其输出反射率越低。实验研究了鸟翼式互抽运相位共轭器的输出特性，获得了器件反射率随入射位置变化的曲线，并建立了四作用区鸟翼式互抽运相位共轭器输出特性的理论模型，数值模拟与实验结果基本一致。
非线性光学 互抽运相位共轭效应 类电子学 四波混频 光学学报
2011, 31(12): 1219001
一般多重网格算法求解光强度传播方程是从精细网格层开始计算, 精细网格层的初值选择影响算法的收敛速度和求解精度。提出了一种完全多重网格方法求解光强度传播方程的相位恢复方法。基于限制法将最细网格上的方程转化为最粗网格上的方程, 求解该方程得到最粗网格上的解; 然后对此解用延拓法得到上一层细网格上的解, 以得到的解作为此层网格上的初解, 利用Ⅴ循环解此层上的方程, 得到此层网格的精确解。依次, 直到得到最细网格上的精确解。模拟相位恢复实验结果表明, 本文方法具有较快的收敛速度, 能够恢复复杂相位分布。
傅里叶光学 相位恢复 光强传播方程 完全多重网格法
