Compact two wavelength Brillouin fiber laser sensor with double Brillouin frequency spacing

摘要

A compact two wavelength Brillouin fiber laser (BFL) sensor with double Brillouin frequency spacing is proposed and demonstrated. In the experiment, 20 m polarization maintaining fiber is used as the sensing element and Brillouin gain medium. This short cavity configuration not only guarantees single longitudinal mode operation of two Stokes wavelengths, but also can effectively reduce external perturbations, complexity and noise of BFL in the absence of an erbium-doped fiber amplifier in intra-cavity. In experiment, about 2 MHz/degrees C sensitivity of beat frequency between the pump and the 2nd-order Stokes wavelength keep in good agreement with the theoretical value. Meanwhile, 0.2 degrees C temperature stability and +/- 0.1 dB power fluctuation are better than the traditional structure. The system is simple and stable, making it convenient for more applications.