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The characteristic analysis of L-band EDFA gain and gain enhancement

Based on the analysis of conventional L-band EDFA we demonstrate a novel structure that improves the L-band amplification performances. In conventional L-band EDFA, 35nm (±1dB) flattened amplification bandwidth from 1565 to 1600 nm is obtained. Small signal gain of 25dB is achieved at 1590 nm with input power of -30dBm and the saturated output power reach to 10dBm. The linear relation between pump power and signal power are demonstrated experimentally. By utilizing a fiber Bragg grating (FBG) with center wavelength of 1550 nm, the population inversion of EDFA is intensified, which gives rise to gain improvement. Experimental results show that the signal gain is enhanced by the FBG by more than 8dB. The use of FBG has also shown a better performance in gain clamping. The amplifier gain is clamped at 25dB with a gain variation of less than 0.5dB for input power as high as -15dBm.