Quasiphase matched second-harmonic generation from periodic optical randomization of poled polymer channel waveguides

We present experimental evidence of quasiphase-matched second harmonic generation in a polymer channel waveguide consisting of disperse red one (DR1) grafted to a poly(methylmethacrylate) (PMMA) main chain polymer at 30% molecular weight concentration. The ability of DR1 to photoisomerize is used to define a periodic segment of linear and nonlinear domains along the waveguide by photodepoling through a photolithographic mask of 10 μm periodicity, following quasiphase-matching requirements. A broad spectral scan between 1450 and 1800 nm evidences a peaked enhancement of second harmonic generation at 1536 nm, with experimental efficiency of 0.023% W−1, further compared to theoretical values. Wavelength dispersion of the quasiphase matched second harmonic peak as well as the penetration depth of the photodepoling beam in DR1 PMMA are also discussed.