Tuning range and spectral selectivity of the distributed forward coupled (DFC) laser

The tuning performance and spectral filtering mechanism in the distributed forward-coupled (DFC) laser diode are investigated. This widely tunable device is based on codirectional mode coupling along the entire laser length by a gain/loss grating perturbation. Due to the transverse integration, even rather short (L approximately=300-600 mu m) DFC lasers may achieve side-mode suppression superior to that of previous codirectionally coupled devices over similar tuning ranges. Model calculations yield a tuning range above 100 nm at 1.5- mu m wavelength with a side-mode suppression ratio around 30 dB.<
>