Key Laboratory of the Ministry of Education on Optoelectronic Information Technology, School of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China.
Institute of Modern Optics, Nankai University, Tianjin 300350, China.
Sensors (Basel). 2019 Jan 30;19(3):593. doi: 10.3390/s19030593.
A wavelength step-swept light source (WSSL) using a recirculating frequency shifter loop (RFSL) based on a single-side-band (SSB) modulator is proposed, in order to achieve a linear and fast wavelength-sweeping. The swept step can be tuned from 1.2 pm to 128 pm by adjusting a precise and stable radio frequency (RF) signal that is applied to the SSB modulator. The swept rate can be tuned up to 99 kHz in a range of over 5.12 nm. Wavelength-to-time mapping is used to measure static strain-induced or temperature-induced shifting of the reflected central wavelength of a fiber Bragg grating (FBG). Because of the high linearity of the light source, the interrogation linearity of the strain and the temperature are as high as 0.99944 and 0.99946, respectively. When a dynamic periodic strain applied to FBG sensor, the dynamic performance of the FBG sensor is successfully recorded in the time domain and its power spectral density of a fast Fourier transform (FFT) is calculated. The signal-to-noise ratio (SNR) of the power spectral density is over 40 dB for a 100 Hz dynamic strain and the calculated sensitivity is 0.048 με/Hz. A sharp change in the strain frequency from 100 Hz to 500 Hz is captured in real time.
提出了一种基于单边带（SSB）调制器的循环频率移位器环（RFSL）的波长步进光源（WSSL），以实现线性快速波长扫描。通过调整应用于 SSB 调制器的精确稳定的射频（RF）信号，可以将扫描步长从 1.2 pm 调谐到 128 pm。在超过 5.12nm 的范围内，扫描速率可高达 99 kHz 进行调节。波长-时间映射用于测量光纤布拉格光栅（FBG）的反射中心波长的静态应变诱导或温度诱导移动。由于光源的高度线性，应变和温度的检测线性度高达 0.99944 和 0.99946。当周期性动态应变施加到 FBG 传感器时，成功地在时域中记录了 FBG 传感器的动态性能，并计算了其快速傅里叶变换（FFT）的功率谱密度。对于 100 Hz 的动态应变，功率谱密度的信噪比（SNR）超过 40 dB，计算出的灵敏度为 0.048 με/Hz。实时捕获应变频率从 100 Hz 到 500 Hz 的急剧变化。
