Design and Analysis of L-shape Defect-based 2D Photonic Crystal Waveguide for Optical Interconnect Application With Signal Amplification

Photonic crystal (PhC) has witnessed an unprecedented research interest since its discovery by Yablonovitch and John in 1987. PhC has undergone substantial theoretical and experimental study because of its periodic dielectric structure and ability to guide and manipulate light at the optical wavelength scale. The photonic band gap (PBG), one of the fundamental characteristics of PhC, prohibits the transmission of light inside a definite wavelength range. The PBG property of PhC opens up enormous opportunities for envisioning a wide range of applications like communication, filtering, bio-sensing, interconnector, modulator, polarizer, environmental safety, food processing etc. However, a peculiar property can be observed when defects are added to PhC, the periodicity of this dielectric structure is disrupted, allowing PC to exhibit high electromagnetic field confinement, a little more volume, and feeble confinement loss. The propagation of light can be altered and engineered by altering the structural characteristics of PhC or introducing appropriate materials into the rods of PC. Among the different applications, optical interconnect is the most escalating application in a photonic integrated circuit. This chapter addresses a novel 2D photonic crystal waveguide for optical amplifier application. The proposed structure comprises 9×9 circular rods of Si with air in the background. A sequence of Si rods is removed to create a defect in the 90o shape. The finite difference time domain method (FDTD) can be adjusted to envisage the electric field allocation along the 90o bend defective region. Several geometrical factors, such as the radius of the Si rods and the gap between lattices, are judiciously optimized in order to realize strong light confinement inside the defect region. The intensity of incident light and the transmitted light is evaluated through numerical analysis, where it is found that the transmitted intensity from the waveguide is much higher than the intensity of incident light, which ensures that the projected construction can act as an optical amplifier. Apart from this, the bending loss close to the bending area of the photonic waveguide is investigated. A small bending loss of the order of 10-5 exists, which indicates efficient guidance of light along the 90o bend path. Lastly, the confinement loss along the defect region is studied, which is found to be in the order of 10-11. So, the light propagation with negligible loss indicates that the future PCW could be an appropriate applicant for optical interconnect applications.

Keywords: Bending loss, Confinement loss, FDTD, Nonlinearity, Optical interconnect, Photonic crystal waveguide.