TUNING RANGE AND SPECTRAL SELECTIVITY OF THE DISTRIBUTED FORWARD COUPLED (DFC) LASER

The tuning performance and spectral filtering mechanism in the newly d eveloped distributed forward coupled (DFC) laser diode are investigate d. This widely tunable device is based on the codirectional mode coupl ing along the entire laser length by a gain/loss grating perturbation. Due to the transverse integration, even rather short (L almost-equal- to 300-600 mum) DFC lasers may achieve side-mode suppression superior to that of previous codirectionally coupled devices at 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.