Conversion of spectral characteristics of laser radiation in periodic domain structures written by the electron-beam method in planar waveguides formed by Ti diffusion in Y-oriented LiNbO3

Periodic domain structures for nonlinear conversion of spectral characteristics of laser radiation in the planar Ti : LiNbO₃ waveguide have been formed by the method of electron-beam writing. Domain gratings with a spatial period of 6.50 μm formed in the Y-cut plate over a wide range of accelerating voltages have been visualised by the method of second harmonic generation microscopy (SHG-microscopy) in transmitting geometry and at waveguide excitation. It is found that the domain structure written at an accelerating voltage of 10 kV in a waveguide with an exponential refractive index profile and an effective thickness of 1.75 μm is characterised by high homogeneity. It is composed of continuous domain rows and provides near-quasi-phase-matching radiation conversion at a wavelength of 1053 nm into the second harmonic for the TE₀ → TE₁ waveguide process.