Characterization of α-phase soft proton-exchanged LiNbO_3 optical waveguides

Abstract

Waveguides in LiNbO3 are realized by a soft proton exchange (SPE) process with use of a melt of stearic acid highly diluted by lithium stearate. No phase transitions are formed when alpha-phase waveguides are obtained by SPE. The alpha-phase presents the same crystalline structure as that of pure LiNbO3 crystal, and it maintains the excellent nonlinear and electro-optical properties of the bulk material. The kinetics of the SPE method is studied by the use of secondary-ion mass spectrometry and prism-coupling techniques. The hydrogen effective diffusion coefficient as well as the self-diffusion coefficients of H+ and Li+ ions are determined as a function of the proton-exchange temperature for X-cut LiNbO3.

Quantum photonics at telecom wavelengths based on lithium niobate waveguides

“…This soft alteration of the crystalline structure preserves the LN optical properties. In addition, this technique allows higher refractive index jumps leading to a more efficient optical confinement with respect to the other techniques presented above [54].…”

“…This depends on the geometrical characteristics of the waveguide (width, depth) and on the refractive-index profile [49,54] induced by the waveguide fabrication. The latter information is usually obtained using the so-called m-line technique [55,56].…”

Subsurface disorder and electro-optical properties of proton-exchanged LiNbO3 waveguides produced by different techniques

“…However, using this method only a partial suppression of the subsurface disorder and the related degradation of waveguide properties were obtained [8]. In this paper we show that, using the soft proton exchange (SPE) process [9]− [11] known as allowing the fabrication of low loss and highly efficient nonlinear components, we obtain waveguides in the α-phase [12,13] and free from any water loss [6,8,14], and therefore, we avoid completely these undesirable effects.…”

Design of the New Type Integrated-Optical Elements for E-Field Sensor

“…At the same time, our study opens the new possibilities for fast and easy estimation of performance of any newly developed LN-based materials (modified by doping or stoichiometry control) for application in integrated-optical sensing elements those feasibility is limited mainly by the PRD and light-induced contribution to the DC-drift effect. The phase composition of the novel waveguide structures formed with APE and soft proton exchange (SPE) 4 has been determined by Raman spectroscopy data. The optimal fabrication conditions for obtaining homogeneous waveguiding layers via the PE techniques can be identified, using this method.…”