Observation of spectral power exchange in fiber Bragg grating stabilized 980 nm pump lasers

Abstract

Abstruct: External wavelength stabilization of high power 9 8 h n pump lasers is observed to caiise an e.~change of power between anipl$eieti spontaneous enzission (ASE) and stimulated emission (SE) over the operating range of the device. This &ct is difjicult to detect in the ,fiber coip[eo' power versus dvive current (L-1) cliaracteristic hecciuse the variations in ASE and SE tend to compensate one another, resulting in a nearly linear relationship between output power and drive ctirrent. This phenonienon becomes evident when the outpit is separuted spectrully into ASE and SE coniponents. and is also evident in tlie rear ,fiicet monitor signal. The exchange between ASE und SE is attributed to an alteration of tlie gain/f&edbach-relationship caused by U shift of /he laser diode cavity modes d a t i v e to the Bragg grating wavelength as drive current is changed.