Complex-coupled wavelength-selectable dfb laser source for coarse WDM

A dual wavelength-selectable InGaAsP/InP distributed feedback (DFB) laser with a complex-coupled Bragg grating is presented. An n-doped reverse layer is buried periodically in the index-coupled Bragg grating, which causes a spatial modulation of the carrier concentration in the active region, and so induces the weak gain-coupled to the index-coupled grating. Two wavelengths of 1.51 um and 1.53 um are realized under different work conditions. The side mode suppression ratios (SMSRs) of both wavelengths reach 40 dB benefiting from the single-mode character of the complex-couple grating. This device can be used in coarse wavelength division multiplexer (CWDM) communication system as the light source because of its low-cost and convenience.