Experimental research of relative intensity noise of semiconductor lasers

The goal of this article is to present a measuring system,which is appropriate to industry measuring and science research,for relative intensity noise (RIN) of semiconductor lasers.The advantage of the system is simple and flexible.The RINs of some semiconductor lasers (with different cavity length,with or without coating)were measured.Special attention was paid to the effect of coating on the RIN.It is found that the quality stability of the lasers will be improved and the RIN character will be more sensible to feedback with coating than the lasers without coating.The reflectivity of coating should be chosen carefully according to the real application conditions,and the reflection of the front facet coating should not be too small.