ASE noise attenuation for signal at 1548.4 nm through a sagnac interferometer using high-birefringence fiber which is subjected to temperature changes

Abstract

This paper reports the construction of an experimental setup to attenuate the ASE (Amplified Spontaneous Emission) noise around 1548.4 nm. A Sagnac Interferometer (SI) which uses high-birefringence fiber (Hi-Bi fiber) at 8, 22 and 110 cm is used as band pass filter for attenuating the ASE noise. Temperature variations are made to tune in the filter SI. A test signal containing noise ASE is taken from an erbium-doped optical fiber and a fiber Bragg grating (FBG), therefore the 1548.4 nm signal surrounded for ASE is obtained. This test signal is introduced into the SI filter and the transmitted power of the interferometer is measured, the transmitted signal of SI has periodic variations with maximums and minimums, the SI is tuned in with temperature to bring the maximum transmitted power at the same wavelength of the signal 1548.4 nm. We found experimentally that is possible to attenuate the ASE noise contribution around 1548.4 nm by comparing the input test signal versus the output signal at the output port of SI. In addition, we found the displacement of the transmittance with respect to temperature (Δλ/ΔT) and the period of the transmitted power (Δλ).