Spectral analysis of UV-written waveguides in LiNbO3 : Measurement of cut-off wavelengths

UV directly written waveguide procedure in lithium niobate single crystals has held considerable promise because of its single-step process which is well suited for complex micro-optical devices, in addition to the conventional optical integrated circuits. For most applications, single-mode waveguides are essential in order to achieve optimised device performance, and hence the determination of single-mode operating range and cut-off wavelength of the waveguide are fundamental for characterising waveguide optical properties. In this work the authors report the first results of spectral analysis within the wavelength range from 408 to 1750 nm of waveguides that were UV-written at 275, 300.3, 302, and 305 nm wavelengths, for the determination of the single-mode operating range and cut-off wavelength for different writing condition.