A gain-switched laser diode as a low-coherence light source

摘要

We investigated a coherence property of the multi-longitudinal mode oscillation from Fabry-Perot type laser diodes (LDs) under gain-switching operation and confirmed that commercially available common LDs gain-switched had a coherence length of around 120-140 μm with a moderate average power of 1-15 mW. By incorporating a gain-switched LD into an all single-mode fiber interferometer, the low-coherence measurement for estimating the thickness and the refractive index of nacreous layers of a cultured pearl was successfully demonstrated.