Lf. Tiemeijer et al., DIRECT ELECTRONIC COMPENSATION OF THE AMPLIFICATION NONLINEARITY IN SEMICONDUCTOR-LASER AMPLIFIERS, Applied physics letters, 64(16), 1994, pp. 2053-2055
Direct electronic compensation of the inherent amplification nonlinear
ity of semiconductor laser amplifiers is investigated. It is found tha
t operating the active layer junction from a voltage source, which in
theory would hold the carrier density at a constant value, does not re
move the amplification nonlinearity because of the intraband carrier d
ynamics. However, compensation of the nonlinearity is shown to be poss
ible by driving the laser amplifier from a negative output impedance s
ource. Using this at 80 mA drive current compensation of the amplifica
tion nonlinearity is demonstrated for a 1310 nm polarization insensiti
ve multiple quantum well laser amplifier showing 18 dB gain (13 dB fib
er to fiber) and a nonlinearity of 0.36 dB/mW. It is further shown tha
t the intraband carrier dynamics, mainly the carrier heating, cause li
mitations to both the driving conditions for which the nonlinearity ca
n be compensated, and to the use of laser amplifiers as an amplifying
detector.