An optical fibre laser characteristic measuring system is presented in this paper. Measurement parameters include laser linewidth, relative intensity noise (RIN) and output power. Homodyne analysis method is used to achieve linewidth which resolution of linewidth can reach 1kHz. Quantization noise of the RIN is decreased greatly. And RIN measuring lower limit reaches -120dB/Hz. Digital Potentiometer is adopted in the detection circuit to adapt to high range of laser power.
Spontaneous combustion in coal goaf area is one of major disasters in coal mines. Detection technology based on
signature Gas is the primary means of spontaneous combustion forecasting of coal goaf area. A real-time remote fire gas
detection system is proposed based on tunable diode laser absorption spectroscopy technology, to achieve valid test of
Carbon Monoxide signature gas. The System uses the wavelength, respectively 1.567um near-infrared band fibercoupled
distributed feedback laser (DFB) as the light source, combined wavelength modulation spectroscopy and
harmonic detection technique, developed a fiber-coupled white-type long-path gas absorption cell, to achieve high
sensitivity detection of gas concentration. The system achieved a remote on-line monitoring of Carbon Monoxide gas
concentration, to meet the fire forecast need for Coal Mine goaf area.