Quasi-phase-matched second-harmonic generation in a GaAs/AlAs superlattice waveguide by ion-implantation-induced intermixing

Abstract

We report type I second-harmonic generation by use of first-order quasi-phase matching in a GaAs/AlAs symmetric superlattice structure with femtosecond fundamental pulses at 1.55 microm. Periodic spatial modulation of the bulklike second-order susceptibility chi(zxy)(2) was achieved with quantum-well intermixing for which the group III vacancies were created by As+-ion implantation. A narrow second-harmonic bandwidth of approximately 0.9 nm (FWHM) with an average power of approximately 1.5 microW was detected, corresponding to an internal conversion efficiency of approximately 0.06%, which was considerably limited by the spectral bandwidth of the fundamental.

Recent advances in phase matching of second‐order nonlinearities in monolithic semiconductor waveguides

“…Shifts in the bandgap energy of 54 nm after IID were recorded. In nonlinear experiments, output second-harmonic powers exceeded 1 μW for the first time in DD-QPM waveguides and the conversion ratio was tripled over that of previous waveguides made by the silica cap method [78]. However, the conversion efficiency was still limited by the large optical losses (21 dB cm 1 ) at the fundamental wavelength which were caused by surface damage from etching the gold implantation mask off.…”

Optical frequency conversion in integrated devices [Invited]

“…MicroRaman spectroscopy has confirmed that first-order gratings can be formed by this technique [82]. As a result, higher SHG conversion efficiencies were recorded [83,84]. We have continued the work on DD-QPM and have achieved even greater performance, which will be discussed in Sec.2.2.…”

Optical Parametric Generators and Amplifiers

“…The vector q has a direction along the direction of the χ (2) modulation and the length of |q| = l c /Λ, where Λ is the spatial modulation period. The modulation of the nonlinearity can be accomplished by periodically inverting the sign of the χ (2) susceptibility, utilizing a zigzag optical path in slabs of nonlinear material with total-internal reflection [11,35,36] or by modulating the amplitude of the second-order susceptibility by periodically modifying the material properties, for instance, by employing quantum-well intermixing in GaAs-AlAs waveguides [37][38][39]. The latter two QPM methods have rarely been used so far either because of the relatively high losses as in the case of the totalinternal-reflection geometry, or due to the small thickness of the modulation which mandates a waveguide geometry for the frequency conversion device.…”