Waveguides and Interferometers : Simulations studies on Photonic Devices using COMSOL Multiphysics®
Lithium Niobate is a popular material for its non-liner optical properties, which is explored for various applications. Of many applications, use of these materials as photonic devices is indeed novel, in recent times. These photonic devices are set to revolutionise the silicon technology and impose challenges to the conventional electronics domain. Through this abstract we discuss the design and fabrication of two different photonic devices, namely a simple waveguide and a Mach-Zehnder interferometer. These devices are initially simulated and then fabricated. LiNbO3-based device comprises of a photonic probe module, light coupling module and a photo detector.
LiNbO3 is deposited using pulsed laser deposition system, on a silicon substrate. The waveguide / Interferometer structure is further patterned using conventional photolithography. The so-formed structure is then subjected to input laser beam of appropriate wavelength to realise the device properties, such as propagation properties and interferometric behaviour.
Before doing these studies, experimentally, the structure was carefully studied using COMSOL Multiphysics® software module. Modelling and simulation of a ridge waveguide and a Mach - Zehnder interferometer was done. An optical ridge waveguide is made; width was chosen as 3 microns for 1550 nm wavelength electromagnetic wave. Substrate material chosen was Sapphire, over which 300 nm LiNbO3 was chosen as the waveguide material. The geometry is done in 3D model. Beam envelope method in wave optics module was chosen because the waveguide size is 103-106 times larger than wavelength. Refractive index, wavelength, width of wave guide and frequency were defined as parameters. After creating the geometry, a physics controlled meshing was done. At one end wave excitation was given and a power of 1W was applied. At the other end no wave excitation is given. Boundary mode analysis and frequency domain analysis were chosen. Similar studies were done for Mach -Zehnder interferometer. The geometry was done in 2D model to obtain curve shape and then extruded to obtain 3D model. The simulation was done with different frequency and different materials such as silicon as substrate.
The analysis of the simulation results and their correlation with the experimental data will be done in this presentation.
