Two-stage reflective-type erbium-doped fiber amplifier with enhanced noise figure characteristics

56.6 dB high gain L-band EDFA utilizing short-length highly-doped erbium rare-earth material

“…However, the gain coefficient in the L-band window is smaller than that in the C-band, higher pump power and longer length of the doped fiber are normally used with L-band EDFA [5]. In literature, various gain enhancement techniques have been proposed to enhance the gain of L-band EDFA such as using narrow-band end-reflectors to feed a small fraction of the amplified spontaneous emission (ASE), up to a few tenths of a milliwatt, back into the EDF [6], utilizing unwanted backward ASE as a secondary pump source for the un-pumped section of erbium-doped fiber (EDF) [7], placing an optical circulator between two EDF segments in a two-stage reflective-type amplifier structure [8], utilizing a bidirectional pumping structure via inserting a 980 nm pump laser diode in the input part [9], incorporating a fiber Bragg grating (FBG) to reflect part of the C-band backward ASE into the EDF [10]− [13] or tunable band-pass filter in a double-pass configuration [14], adding a short length of forward pumped EDF in front of a double-pass amplifier [15], using loop configuration and a C-band seed signal [16]. Among the other gain enhancement techniques proposed is the use of a two stage structure with a bypass isolator [17] or in-line FBG with forward-backward pumping scheme [18], a three-stage structure of EDF pumped by 980 nm and 1480 nm laser diodes, which can achieve 35 dB gain with 5 dB noise figure [19] and the use of residual pump power in a three-stage configuration [20]− [21].…”

Performance evaluation and optimization of dual-stage L-band EDFA utilizing short gain medium

“…A multi-stage design, which contains two or more stages of EDF, has been demonstrated as another design to achieve high gain EDFA [11][12][13][14]. The concept from the multistage amplifier is that the input signal can be amplified twice or three times which leads to increase in the gain and reduction in the noise figure by incorporating a bypass isolator [12].…”

Optimization of the two-stage single-pump erbium-doped fiber amplifier with high amplification for low frequency nanoscale pulses

“…One of these brings the double propagation of the signal beam into the amplifier by using mirrors at the output end of the erbiumdoped fiber ͑EDF͒. [1][2][3][4] Another suppresses the unwanted amplified spontaneous emission ͑ASE͒ noise, 5-7 providing significant improvement in signal gain. Also, optical isolators and optical filters have been inserted to avoid ASE noise, causing fast saturation in the EDF.…”