Characterization of strained quantum well InGaAs/AlGaAs buried heterostructure lasers using internal second-harmonic generation

Abstract

In this paper the investigation of internal optical second harmonic generation (SH) of buried heterostructure (BH) InGaAs/AlGaAs strained quantum well laser diodes is performed for additional characterization of these devices which are capable of operating at high power densities as high as 3 MW/cm<SUP>2</SUP> at room temperature and 0.1 MW/cm<SUP>2</SUP> at 190 degree(s)C. The blue-green emission level is of the order of 10<SUP>5</SUP> photons per second for laser diodes with 3micrometers active layer width at fundamental optical power of 2.0 mW. This relatively high SH intensity level makes it possible to observe the light spot in optical microscopes and to detect SH signal with a standard photon counting system in wide operation current and ambient temperature intervals. Variation of the SH signal at the constant fundamental harmonic (FH) power indicates that changes in the near field occur. SH far-field patterns of laser diodes reflect the effects of SH radiation spot size reduction in comparison with FH radiation spot size and FH waves nonlinear interactions in the waveguide material.