Letter Phase-mismatching effects in the internal second-harmonic generation in InGaAs quantum-well laser diodes

Abstract

We have characterized the role of phase-mismatching in the spectral distribution of the internal second-harmonic generation (ISHG) in the CW operation of high-power InGaAs quantum-well laser diodes emitting at around 960 nm. The observed pairs of narrow blue-green peaks of ISHG have symmetrical spectral positions with respect to the central peak of the pure second harmonic at ∼480 nm, suggesting that their generation in the laser waveguide is most probably mediated by a mechanism of reciprocal cancellation of the respective phase-mismatch vectors. The relatively strong emission of the ISHG radiation at the output mirror facet indicates that this second-order nonlinear optical process is enhanced by waveguiding in the laser active region.