Real-time fiber Bragg grating measurement system using temperature-controlled Fourier domain mode locking laser

We constructed a temperature-controlled Fourier domain mode locking (TC-FDML) laser capable of high-speed wavelength sweeping and developed a real-time fiber Bragg grating (FBG) measurement system. The TC-FDML laser can perform high-speed wavelength sweeping at a sweep frequency of 50.7 kHz with a scan range of ∼60 nm in the 1.55-μm band. This system uses a data acquisition system mounting an analog/digital converter and field programmable gate array that enables real-time FBG measurement at a sampling frequency of 250 MHz. Using bidirectional wavelength sweeping by the TC-FDML laser, the system has a measurement time resolution of 9.9 μs. We show that the developed system can measure high-speed vibrations of several kHz and perform simultaneous and continuous measurements of multiple FBGs for a period of one hour.