TEMPORAL RESPONSE OF SEMICONDUCTOR TRAVELING-WAVE OPTICAL AMPLIFIERS TO AN EXPONENTIALLY VARYING INPUT SIGNAL

A theoretical treatment of the propagation of optical signals through semiconductor travelling wave amplifiers (TWAs) is presented. Analytic solutions are obtained for the temporal behaviour of the output for a mplifiers subject to input signals composed of an exponentially varyin g small signal superimposed on a large time-independent signal. The fo rmulation includes the spontaneous recombination term and the line-wid th enhancement (anti-guiding) factor. The solution obtained may be rea dily interpreted as a combined amplitude and phase modulated output si gnal. The analysis also clearly reveals the combined effects of the sp ontaneous recombination rate and the time constant of the exponentiall y varying input signal. Tn this way a total description of the respons e of the optical amplifier is obtained.