Dual-Wavelength FBG Laser Sensor Based on Photonic Generation of Radio Frequency Demodulation Technique

Abstract

Based on the radio frequency (RF) demodulation technique, a novel dual-wavelength fiber laser sensor is proposed and demonstrated experimentally. A beat sensing signal, which is generated by the coherently mixing output of a dual-wavelength laser in a high frequency photodetector, has been obtained and demodulated by a radio-frequency spectrum analyzer (RFSA). By employing a LiNbO 3 modulator, high-frequency beat signal can be tuned arbitrarily to tens or hundreds of megahertz without distortion and thus a lowfrequency RFSA can be used. When a strain is applied on the laser sensor, the detected beat signals will be shifted with a strain sensitivity of about −8.11 kHz/με.

Detection of Gas Concentration by Correlation Spectroscopy Using a Multi-Wavelength Fiber Laser

“…Many methods for gas detection have been developed. Laser technologies [1][2][3], which have significant applications in all kinds of lines, are also used for the detection of gases. Using the Beer-Lambert law, gas concentration can be easily measured with a single-mode tunable laser which scans in a continuous wavelength range including some absorption peaks of the target gas.…”

Hydrostatic Pressure Sensor Based on a Gold-Coated Fiber Modal Interferometer Using Lateral Offset Splicing of Single Mode Fiber

“…Optical fiber sensors [1][2][3][4][5][6][7][8][9][10][11][12][13] have attracted considerable attention in the past several decades due to their wide applications for a great variety of measurements such as temperature, strain, chemical concentration, refractive index, hydrostatic pressure and their advantages such as small size, light weight, high sensitivity, multiplexing capability, and immunity to electromagnetic interference. Among them, several hydrostatic pressure sensing techniques have been developed, which include hydrostatic pressure sensors based on birefringent fibers [14][15][16], photonic crystal fibers (PCFs) (or microstructured fibers) [17][18][19][20][21][22][23][24], fiber Bragg gratings (FBGs) [18], and Fabry-Pérot interferometers (FPIs) [25][26][27].…”

Dual-π-phase-shift distributed fiber laser for strain sensing

“…Then multi-mode ring fiber laser has been applied as strain sensor [8][9][10]. As a compact sensing device, a sampled fiber grating laser with equivalent phase shift was reported to have strain sensitivity of -8.1 kHz/με in 2009 [11]. In our research, we apply a dual-π-phase shift DFB FL for strain sensing, whose sensing performances under monolithic and local strain are discussed, for wavelength-and bear-frequency demodulation method respectively.…”