Effects of a buffer layer on TM modes in a metal-clad optical waveguide using Ti-diffused LiNbO(3) C-plate

Area of Science:

• Photonics and Waveguide Technology
• Materials Science for Optical Devices
• Integrated Optics

Background:

• Titanium-diffused Lithium Niobate (LiNbO3) waveguides are crucial for integrated optics.
• Metal cladding can induce losses in Transverse Magnetic (TM) modes.
• Buffer layers are often used to mitigate unwanted optical effects.

Purpose of the Study:

• To investigate the impact of a silicon dioxide (SiO2) buffer layer on TM modes in metal-clad Ti-diffused LiNbO3 optical waveguides.
• To analyze how buffer layer thickness affects optical loss, absorption, and mode transformation.
• To understand the role of transverse load impedance in metal-clad waveguides.

Main Methods:

• Numerical solutions of dispersion equations were employed.
• Analysis focused on the transverse load impedance of the waveguide.
• The Ti-diffused region's permittivity was modeled as linearly decreasing from the surface.

Main Results:

• The thickness of the SiO2 buffer layer was found to directly influence TM mode loss reduction.
• Specific buffer thicknesses were identified to minimize absorption peaks.
• Mode transformation characteristics were clarified in relation to buffer film thickness.

Conclusions:

• A SiO2 buffer layer is effective in reducing TM mode losses in metal-clad Ti-diffused LiNbO3 waveguides.
• Optimizing buffer layer thickness is critical for managing optical loss and mode behavior.
• The study provides valuable insights for designing advanced optical waveguide devices.