LiNbO ₃ proton-exchanged waveguide layers: Phase composition and stress

Abstract

An analysis of phase composition of proton-exchanged waveguide layers in LiNbO3 of X, Y and Z crystallographic orientations has been performed based on the mode and IR absorption spectra. Obtained at different technological conditions, the waveguides studied show complex phase composition with different quota of the phases present. The intrinsic stress caused by crystal lattice deformations at a relatively high level of hydrogen doping in the proton-exchanged layers has been estimated by the optical integral method. The results contribute to a better understanding of the properties and characteristics of such waveguides.

Phase composition and stress in LiTaO 3 proton-exchanged optical waveguides

“…MS evaluation. The layer stress and the compressibility coefficient were calculated by use of the optical integral method [8] which has been described in our previous paper concerning PE waveguides in LN [9]. The method is based on the detection of the change in the interference fringe patterns between the substrate and an optical flat which was used to measure the deformation of the layersubstrate (Li 1−x H x TaO 3 -LiTaO 3 ) system.…”

Phase Composition of HiVac-VPE Lithium Niobate Optical Waveguides Identified by Spectroscopic Investigations

“…Various methods were used to study the H x Li 1−x NbO 3 phases in proton-exchanged LiNbO 3 optical waveguides: X-ray diffraction, M-lines mode spectroscopy, secondary ion mass spectrometry, thermo-gravimetric analysis, differential scanning calorimetry, forward recoil spectrometry, Rutherford backscattering spectrometry, Raman spectroscopy, IR reflection spectroscopy, IR absorption spectroscopy, and UV-VIS absorption spectroscopy . The existence of six to seven phases of H x Li 1−x NbO 3 (depending on the crystallographic orientation of the main surface of the crystal plate) has been established in waveguides fabricated using various proton exchange techniques, including Proton Exchange, Annealed Proton Exchange, Soft Proton Exchange, Vapor-phase Proton Exchange, and High Index Soft Proton Exchange [9,10,15,19,22,25,27]. The specific Raman and IR reflection/absorption spectra are observed for each phase [9][10][11][12][13][14][15][16][17]19,21,24].…”

“…The existence of six to seven phases of H x Li 1−x NbO 3 (depending on the crystallographic orientation of the main surface of the crystal plate) has been established in waveguides fabricated using various proton exchange techniques, including Proton Exchange, Annealed Proton Exchange, Soft Proton Exchange, Vapor-phase Proton Exchange, and High Index Soft Proton Exchange [9,10,15,19,22,25,27]. The specific Raman and IR reflection/absorption spectra are observed for each phase [9][10][11][12][13][14][15][16][17]19,21,24]. Therefore, for identification of any H x Li 1−x NbO 3 phase in waveguides fabricated by other techniques, such as the case of our HiVac-VPE [1][2][3] or Reverse Proton Exchange [24], it is sufficient to use optical spectroscopy data.…”

Interface and thickness dependent domain switching and stability in Mg doped lithium niobate

“…[50][51][52][53] The original lines of the substrate are still present, but broadened and changed in intensity (Figure 6(a)). A characteristic phonon frequency of 680 cm À1 originated in distortion of Nb 5þ octahedra towards non polar states [52][53][54] exhibits a high intensity in exposed PE areas. Only the edge of a PE band 53 located at 69 cm À1 is visible within the measured spectral range.…”

“…A characteristic phonon frequency of 680 cm À1 originated in distortion of Nb 5þ octahedra towards non polar states [52][53][54] exhibits a high intensity in exposed PE areas. Only the edge of a PE band 53 located at 69 cm À1 is visible within the measured spectral range. A new peak at 960 cm À1 appears and is assigned to OH -librational bands that are strongly dependent on the proton exchange phase.…”