Quasiphase matched surface emitting second harmonic generation in periodically reversed asymmetric GaAs/AlGaAs quantum well waveguide

Abstract

. (1997). Quasiphase matched surface emitting second harmonic generation in periodically reversed asymmetric GaAs/AlGaAs quantum well waveguide.

Patterning the second-order optical nonlinearity of asymmetric quantum wells by ion implantation enhanced intermixing

“…2 for wavelengths between ϭ1480 and 1600 nm. The SH spectrum from the unimplanted section is similar to that measured previously for the as grown waveguide, 5 except for a slight reduction of the SH exciton resonance relative to the interband background signal. This may be due to a low but finite concentration of nonradiative defects introduced during fabrication.…”

“…Although the susceptibility modulation will be smaller [2][3][4][5] than that obtained by crystal domain QPM, 6 patterned quantum well intermixing uses a much simpler fabrication process. The magnitude of (2) in an AQW superlattice [2][3][4][5] is comparable to that of many commonly used nonlinear crystals, and is easily modified using quantum well engineering techniques. Ion implantation enhanced quantum well intermixing is one such technique which has attracted much interest for post-growth fabrication of active and passive optical telecommunication components on a single wafer.…”

“…A counterpropagating beam was provided by the reflection of the input beam from the end facet of the waveguide. The interaction of counterpropagating TE and TM components of the pump light 5,14 generates SHG light that is radiated along the surface normal. This surface-emitted SHG ͑SESHG͒ light was imaged onto a cooled CCD array positioned above the waveguide.…”

“…11 In WDM applications, the frequency shift ⌬ is very small and the sum frequency susceptibility is similar to the SH susceptibility measured in this experiment. As described in our previous work, 5 we use a unique surface emitting QPM waveguide geometry to separate the SHG response of the AQW superlattice from the larger bulk GaAs/AlGaAs response. In this work, an ion implantation mask is arranged to create intermixed and unchanged sections along a single AQW waveguide ridge.…”

“…15 The magnitude of (2) has been measured to be approximately 20 pm V Ϫ1 at the exciton peak for the as grown superlattice. 5 The key parameter for designing intermixed QPM waveguides is the SH susceptibility difference ⌬ (2) between unimplanted and intermixed AQWs. Since the surface-emitting QPM resonance line shape is flat over the wavelength range in Fig.…”