B. Tromborg et al., TRAVELING-WAVE ANALYSIS OF SEMICONDUCTOR-LASERS - MODULATION RESPONSES, MODE-STABILITY AND QUANTUM-MECHANICAL TREATMENT OF NOISE SPECTRA, IEEE journal of quantum electronics, 30(4), 1994, pp. 939-956
We present a traveling wave analysis of a general class of semiconduct
or lasers, which includes multisection DFB/DBR lasers and gain-coupled
DFB lasers. The analysis leads to new semianalytic expressions for th
e small-signal IM and FM modulation responses, the intensity and FM no
ise spectra, and the linewidth. The expressions are given in terms of
solutions to four coupled linear homogeneous differential equations an
d can easily be evaluated numerically. We also derive a stability para
meter sigma, for which sigma < 0 indicates that the mode is unstable w
ith respect to small-scale fluctuations. The noise spectra are derived
from semiclassical calculations as well as from calculations based on
quantized fields, and we discuss the limitations of the semiclassical
approach. The formalism of the quantum mechanical treatment has a bui
lt-in relationship between the relative intensity noise and the noise
of the injection current. This relationship is discussed and illustrat
ed by numerical examples.