halbleiterlaser, modulation method and optical communication system

摘要

A semiconductor laser (1) includes a distributed feedback semiconductor laser structure having a plurality of regions (124, 125a, 125b; 224, 225a, 225b). The regions are electrically separated from each other. A phase shift section (21a, 121a, 221a) is provided in a grating (21, 121, 221) in one (125a, 225a) of the regions. In the semiconductor laser, alpha parameters for transverse electric (TE) and transverse magnetic (TM) polarization modes, in the vicinity of threshold currents for the TE mode and the TM mode, are made different from each other. An alpha parameter is defined by 4 pi / lambda .(dn/dN)/(dg/dN), where lambda is a Bragg wavelength, n is an effective refractive index, N is an injection carrier density and g is a gain for each of the TE mode and the TM mode. IMAGE