DEMONSTRATION OF BROAD-BAND TUNABILITY IN A SEMICONDUCTOR-LASER USING SAMPLED GRATINGS

We propose and demonstrate a new monolithic laser structure in which the fractional tuning range DELTA-lambda/lambda can be more than an order of magnitude larger than the fractional index change DELTA-mu/mu in one section. The key idea involves using grating mirrors with grating elements removed in a periodic fashion. These "sampled gratings" have reflection spectra with periodic maxima. By using two such mirrors with identical grating pitch but mismatched sampling periods, it is possible to tune among the various reflectivity maxima. our initial experimental results show 29.3 nm of tuning in an InGaAsP laser.