Demonstration of broadband tunability in a semiconductor laser using sampled gratings

摘要

We propose and demonstrate a new monolithic laser structure in which the fractional tuning range Dgr;lgr;/lgr; can be more than an order of magnitude larger than the fractional index change Dgr;mgr;/mgr; in one section. The key idea involves using grating mirrors with grating elements removed in a periodic fashion. These lsquo;lsquo;sampled gratingsrsquo;rsquo; 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.