Research On L-band Broadband Erbium-doped Fiber Source

Erbium-doped fiber source has advantages of high power,good mean wavelength stability,broad bandwidth and long lifetime,which is considered as a high-precision optical fiber gyroscope ideal source.At present,most Erbium-doped fiber sources operate in the C band.Since the C-band fiber source produces a Gaussian peak that limits the bandwidth of the spectrum,the spectrum must be flattened by additional development techniques.L band Erbium-doped fiber source have a flat spectral output and 3dB bandwidth can read nearly 40nm,which is conducive to eliminate the non-reciprocal phase nosie in fiber optic gyroscope caused by the Rayleigh scattering and Kerr effect.The purpose of this paper is to design a scheme that produces L-band broadband fiber sources to meet the requirements of fiber optic gyroscopes.In this paper,the luminescence mechanism and physical model of Erbium-doped fiber source are introduced in detail.The effects of pump power,Erium-doped fiber length and reflectance on the spectral shape,power,3dB bandwidth and mean wavelength of output source are predicted by simulation.The constant current circuit and temperature control circuit are designed to ensure the stability of the output power of the pump source.The current in whole temperature range is changed by 0.05mA and the temperature coefficient is 0.5ppm per degree.When the temperature changes from-40 degree to +50 degree,the internal working temperature has changed 0.3 degree.Three different configurations of L-band fiber sources are constructed,including a single-stage double pass forward structure,a single-stage double pass backward structure with absorptive Erbium-doped fiber and a two-stage double pass forward structure.The first structure outputs source with power of 0.103mW,3dB bandwidth of 36.4nm,the mean wavelength of 1584.9.The second structure outputs source with power of 0.128mW,3dB bandwidth of 38.2nm,mean wavelength 1583.6nm.In particular,the first Erbium-doped fiber using low concentration doped optical fiber,the output source has the power of 0.157mW,the 3dB bandwidth of 35.4nm and mean wavelength of 1583.6nm.The third structure outputs source with power of 1.502mW,3dB bandwidth of 37.6nm,mean wavelength of 1585.5nm.Finally,source produced by the third structure is used in fiber optic gyroscope,and the zero drift is 0.358 degree per hour.