Demodulation system for fiber Bragg grating sensors using digital filtering technique

A discrimination measurement method and demodulation technique for fiber Bragg grating (FBG) sensors were presented using digital filtering technique. The system can control a tunable fiber Fabry-Perot filter with sawtooth wave voltage generated by digital clock to interrogate FBG sensors. Using the analogue digital converter (ADC), the reflected FBG signals were sampled with synchronous digital clock. With the aid of digital matched filtering technique, the sampled FBG signals were processed to obtain the maximum signal-to-noise ratio (SNR) and the Bragg wavelength shift from the FBG signals was recovered. The results demonstrate that this system has a scanning range of 1 520 nm–1 575 nm, and the wavelength detection accuracy is less than 2 pm with 1.5 Hz scanning frequency. Supported by Doctoral Foundation of Ministry of Education of China (No. 20040056008). Lü Chengang, born in 1978, male, Dr, lecturer.