A FBG Sensor Based on EDFL with Hybrid Edge Filter

A FBG sensor that uses an Erbium doped fiber laser (EDFL) has been demonstrated. The mode selecting component, FBG, also acts as the sensing element. A High Birefringence Fiber Loop Mirror (Hi-Bi FLM) was used to form the linear laser cavity with FBG. Furthermore, the Hi-Bi FLM combined with Long Period Fiber Grating (LPFG) serving as an edge filter. When the wavelength shift induced by variation on the FBG, the laser cavity loss changes according the loss slope, this results in an output intensity fluctuation responsibly. The variation measurement could be obtained by measuring the output intensity. In this paper, we proposed a high linear slope efficiency of 5.64dB/nm, which is more than two times improvement when compare with conventional LPFG edge filter, such high slope efficiency is greatly beneficial to improve the resolution of sensing system.