Evanescent Coupling Effect in E-skid Waveguide by FDTD Simulation

Abstract

Nowadays in order to deliver optical elements that require fast low power consumption and small size many modern optical elements use semiconductor technology to integrate the optical system on the chip which is the so-called photonic integrated circuit There is an important component in the photonic integrated circuit which is responsible for transmitting optical signals and energy that is the waveguide In order to pursue more effective space utilization and circuit efficiency we need to reduce the size of the chip and make more efficient layout between the optical elements However that will cause the signals in each optical circuit to interfere with each other On the other hand if we want to allow the waveguides to couple to each other we must bend the waveguides to be close to each other There will be a lot of waste in space utilization When the waveguide is bent it will also cause bending loss So how to adjust these coupling effects is an important issue when reduce the size of the chip In this thesis we use the E-skid waveguide structure which can control the effect of directional coupling without change the shape of the waveguide core We use compact FDTD to analyze the E-skid waveguide mode and compared with the strip waveguide E-skid waveguide has multilayer layered SiO2/Si in the cladding region which makes it anisotropic in its dielectric constant Comparing the first-order modes of the 1550nm wavelength with the field cross section we prove that the E-skid waveguide can indeed quickly reduce the evanescent field outside the waveguide to have better confinement For the waveguide coupling the equivalent refractive index in the cladding of E-skid waveguide is larger than that of the strip waveguide This makes E-skid waveguide having a better coupling effect than the strip waveguide In addition if preventing the occurrence of the coupling effect is required we replaced cladding material with multilayer Si/air in the cladding region The cross-sectional field diagram proves that it has a better confinement effect than the original E-skid

Date of Award	2020
Original language	English
Supervisor	Shih-hui Chang (Supervisor)