BROAD-RANGE WAVELENGTH-TUNABLE SUPERSTRUCTURE GRATING (SSG) DBR LASERS

A broad-range tuning is demonstrated in tunable DBR lasers with a newly proposed superstructure grating (SSG). These SSG reflectors were fabricated by electron-beam lithography, and a grating performance was evaluated by measuring the transmittance characteristics of the ridge-type SSG reflector. Incorporating this SSG reflector into DBR lasers results in wavelength-tunable lasers that can cover a wide-wavelength range by using coarse and fine tuning mechanisms. Wavelength-tunable SSG DBR lasers were fabricated and operated under low-threshold CW conditions. Wavelength tuning ranges of 50 and 100 nm were designed and experimentally measured to be 50 and 83 nm, respectively, with single-mode operation. In devices with a 100 nm tuning range, 103 nm tuning was achieved for the first time by including a multimode-wavelength region. The temperature dependence and modulation characteristics of these lasers are stable over their wide tuning range.