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Nonlinearity-compensation-free optical frequency domain reflectometry based on electrically-controlled optical frequency sweep
摘要： A nonlinearity-compensation-free optical frequency domain reflectometry (OFDR) scheme is proposed and experimentally demonstrated based on the electrically-controlled optical frequency sweep. In the proposed scheme, the linear frequency sweep light is generated by propagating an ultra-narrow-linewidth continuous-wave light through an electro-optic frequency shifter which consists of a dual-parallel Mach-Zehnder modulator and an electronic 90° hybrid, where the electro-optic frequency shifter is driven by a linear frequency modulated signal generated by a direct digital synthesizer. Experimental results show that the spatial resolution and signal-to-noise ratio (SNR) of the proposed OFDR scheme without the nonlinear phase compensation are comparable to those of the OFDR employing a commercial tunable light source (TLS), an auxiliary interferometer and a software-based nonlinear phase compensation method. The proposed OFDR scheme is helpful to reduce the complexity of optical structure and eliminate the difficulty of developing nonlinear phase compensation algorithm.
关键词： optical frequency domain reflectometry (OFDR),electro-optic frequency shifter,Dual-parallel Mach-Zehnder modulator,optical fiber sensor
更新于2025-09-23 15:19:57
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Magnetic Optical FBG Sensors Using Optical Frequency-Domain Reflectometry
摘要： The optical frequency-domain reflectometry (OFDR) sensing system and signal processing method, which is based on the short-time Fourier transform, enable us to interrogate reflected wavelengths of fiber Bragg gratings (FBGs) and their relative position along the optical fiber with high spatial resolution. An FBG is an optical fiber with an appropriately inscribed periodic refractive index modulation. When a broadband optical signal is launched into the FBG, narrow wavelength bandwidth is reflected. Due to an attached transducer, such as Terfenol-D, the reflected wavelength changes with the applied magnetic field. The proposed magnetic FBG sensor consists of a small rod of magnetostrictive alloy TbDyFe, also known as Terfenol-D, which has large magnetostriction. The FBG is attached to the Terfenol-D rod with UV glue. Consequently, the external magnetic field is applied to the sensor and as a result, the Terfenol-D rod length increases. The reflected wavelength shift is observed and measured by the OFDR sensing system. Therefore, we determine the external magnetic field along the optical fiber from the reflected Bragg wavelength shift. The measurement results show that the proposed magnetic field sensors based on Terfenol-D using OFDR can be successfully used for measurement of the external magnetic field along an optical fiber.
关键词： Terfenol-D,optical frequency-domain reflectometry (OFDR),magnetic field sensor,Fiber Bragg gratings (FBGs)
更新于2025-09-09 09:28:46