STIMULATED EMISSION IN A PERIODIC STRUCTURE

TLDR

These compact, stable laser devices feature distributed feedback integrated with the gain medium and intrinsic grating‑like spectral filtering. The study aims to analyze how periodic variations in refractive index and gain affect laser threshold and bandwidth. The authors induced index periodicities in gelatin films doped with rhodamine 6G to study laser behavior. Laser oscillation driven by backward Bragg scattering was observed, with characteristic behavior reported near 0.63 µm.

Abstract

We have investigated laser oscillation in periodic structures in which feedback is provided by backward Bragg scattering. These new laser devices are very compact and stable as the feedback mechanism is distributed throughout and integrated with the gain medium. Intrinsic to these structures is also a gratinglike spectral filtering action. We discuss periodic variations of the refractive index and of the gain and give the expression for threshold and bandwidth. Experimentally we have induced index periodicities in gelatin films into which rhodamine 6G was dissolved. The observed characteristics of laser action in these devices near 0.63 μm are reported.