Cavity-enhanced stimulated raman scattering from short GaP nanowires.

We report the first observation of stimulated Raman scattering (SRS) from semiconductor nanowires (SNWs). Using continuous wave (CW) excitation (514.5 nm), very strong nonlinear SRS was observed in backscattering from short segments of crystalline GaP NWs with diameter d = 210 nm when the wire length L < 1.1 microm. The SRS intensity was found to increase dramatically with decreasing L down to 270 nm. The effective threshold pump power P(T) needed to observe the SRS is quite small. Indeed, we observe values of P(T) 3 orders of magnitude smaller than reported for bulk crystals of strongly nonlinear LiIO(3) and Ba(NO(3))(2) and 2 orders of magnitude smaller than that reported recently for SRS from "top-down" fabricated silicon microwaveguides. P(T) was observed to decrease linearly with decreasing L. Our data are discussed in terms of theoretical results developed for dielectric cavities. The quality factors Q for the short GaP cylindrical cavities studied here are estimated to be approximately 15,000. Our results suggest that SNWs may find applications as Raman lasers.