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We report the observation of continuous-wave second harmonic generation for a pump at 1559.9 nm in type-I phase-matched Bragg reflection waveguide using the GaAs/Al(x)Ga(1)1-(x)As material system. For an internal pump power of 94 mW, phase-matched second harmonic power of 23 nW was measured in a waveguide with a length of 1.96 mm and ridge width of 4 mum. The internal conversion efficiency of the process was estimated as 6.8 x 10-(3) %W-(1)cm-(2). The full-width at half-maximum bandwidth of the nonlinear process was found to be 0.91 nm.

The impact of third-order nonlinearities including self-phase modulation and two-photon absorption on the efficiency of the second-harmonic generation is numerically investigated using the split-step Fourier method in phase-matched Bragg reflection waveguides. Also using the same technique, the adverse effects of group velocity mismatch and group velocity dispersion of the interacting frequencies on the efficiency of the nonlinear process are examined and contrasted for optimal sample design. Using an optimized structure, we report efficient femtosecond second-harmonic generation in monolithic AlGaAs Bragg reflection waveguides for a type II nonlinear interaction. For a 190 fs pulsed pump around 1555 nm with an average power of 3.3 mW, a peak second-harmonic power of 25.5 W is measured in a sample with a length of 1.1 mm. The normalized conversion efficiency of the process is estimated to be 2.0ϫ 10 4 % W −1 cm −2. Pump depletion is clearly observed when operating at the phase-matching wavelength.

A design methodology for obtaining versatile interface modes in monolithic structures is discussed. These modes are then utilized in conjunction with total internal reflection modes for phase-matching second-harmonic generation (SHG) in periodic layered media in Al x Ga 1−x As material system. Typical loss values of 2.71 cm −1 for a TE-polarized pump and 4.26 cm −1 for a TM-polarized pump around 1550 nm were obtained. Nonlinear characterizations are carried out using 2 ps, 30 ps, and a continuous wave pump for type-I and type-II interactions. Maximum SHG conversion efficiency of 1.14 × 10 4 % W −1 cm −2 is observed for the type-II process with a pump power of 0.52 mW in a sample with a length of 2.0 mm.

and nonlinear properties. Second harmonic generation is adopted for the demonstration of nonlinear interaction, due to its convenient experimental set-up. Three different laser sources are used to pump the waveguides and second harmonic light is generated and characterized. Coupled interface modes in conjunction with other types of modes also existing within the same structures, offer the possibility to explore three-wave mixing processes such as sum and difference frequency generation.ii