Optical Amplifiers and its Future Uses By :- Paul SouryaChatterjee ECE – 1034 6th Sem. Academy Of Technology
INTRODUCTION The optical fiber amplifier was invented by H. J. Shaw and Michel Digonnet at Stanford University, California (1980s).
Optical communication A typical communications system includes a transmitter, an optical fiber, a receiver, multiplexers and demultiplexers, amplifiers, switches and other components. The transmitter incorporates information to be communicated into an optical signal and transmits the optical signal via the optical fiber to the receiver. The receiver recovers the original information from the received optical signal.
Optical amplifiers vs. regenerators
Semiconductor Optical Amplifier p Single pass chip gain: G increases exponentially with length
Gain ~ wavelength curve Single SOA
Spanning from 1250-1650 nm
Output Power (db)
SOAs are linear for small input powers.
Erbium Doped Fiber Amplifier
1st demonstrated by a group including David N. Payne, R. Mears, & L. Reekie, from the University of Southampton & a group from AT&T Bell Laboratories, E. Desurvire, P. Becker, & J. Simpson.
All optical and fiber compatible
Wide bandwidth 20 ~ 70 nm
High gain, 20 ~ 40 dB
High output power,
Bit rate, modulation format, power and wavelength insensitive
Low distortion and low noise (NF < 5dB)
EDFA Circuit Board
2 Types of Raman Amplifier
However, Distributed Amplifier requires 500 mW power and Lumped Amplifier require upto 1W.
Noisein optical amplifiers
Must be measured electrically. ce
Noise figure Noise Figure (dB)
There is a 3 dB NF limit for complete inversion & high gain.
Amplifier Gain vs. Power
Output saturation power is defined as the output power when gain drops by 3db
Power amplifiers usually operate at saturation.
JSTOR Philosophical Transactions of the Royal Society of London Series A, Mathematical and Physical Sciences, Vol_ 329, No_ 1603 (Sep_ 28, 1989)