Multiple-wavelength distributed-feedback laser arrays with high coupling coefficients and precise channel spacing.

Special designs of sampled Bragg gratings have been used to fabricate distributed-feedback semiconductor laser arrays with very precise wavelength spacing and strong coupling coefficients. By dividing one sampling period into two equal sections, each with a grating but with a π-phase shift between the sections, the ±1st-order channels are enhanced while eliminating the zeroth-order reflection. By using multiple phase-shifted sections, only the -1st-order channel is enhanced. Using a single electron beam lithography step and two π-phase-shifted sections, we have fabricated an eight-channel laser array with a channel spacing of 100 GHz.