QUASI-CONTINUOUS WAVELENGTH TUNING IN SUPER-STRUCTURE-GRATING (SSG) DBR LASERS

The paper describes the design of a super-structure-grating distribute d Bragg reflector (SSG-DBR) laser for broad quasicontinuous wavelength tuning with stable single-mode operation. The phase distributions and the effective coupling coefficients of SSG's are optimized to obtain both broad tuning range and high mode selectivity. A computer-aided si mulation of wavelength tuning, where the effects of the waveguide loss increase and inhomogenious gain spectrum are included, provides an op timum cavity structure and indicates the possibility of more than 70 n m quasicontinuous tuning in a 1.55 mu m InGaAsP-InP SSG-DBR laser. Exp erimental results for 34 nm quasicontinuous tuning with a properly des igned device are also presented.