Numerical techniques for excitation and analysis of defect modes in photonic crystals

Abstract

Two numerical techniques for analysis of defect modes in photonic crystals are presented. Based on the finite-difference time-domain method (FDTD), we use plane wave incidences and point sources for excitation and analysis. Using a total-field/scattered-field scheme, an idealplane wave incident at different angles is implemented; defect modes are selectively excited and mode symmetries are probed. All modes can be excited by an incident plane wave along a non-symmetric direction of the crystal. Degenerate modes can also be differentiated using this method. A proper arrangement of point sources with positive and negative amplitudes in the cavity flexibly excites any chosen modes. Numerical simulations have verified these claims. Evolution of each defect mode is studied using spectral filtering. The quality factor of the defect mode is estimated based on the field decay. The far-field patterns are calculated and the Q values are shown to affect strongly the sharpness of these patterns. Animations of the near-fields of the defect modes are presented to give an intuitive image of their oscillating features.

Photonic crystal characterization by FDTD and principal component analysis

“…A complete description of the simulated structure can be found in Ref. [6]. For a better understanding we have followed the same choices and simulation parameters as those used in Ref.…”

“…For a better understanding we have followed the same choices and simulation parameters as those used in Ref. [6]. The analyzed photonic crystal can support five modes, two of which are degenerated.…”

“…Time-domain computations allow for an unambiguous characterization of important properties of microcavities, such as band-gap features, resonant defect mode dynamics, and far-field pattern properties of crystal modes. The results have frequently been interpreted by use of by fast Fourier transform analysis and filtering techniques [6]. A complete numerical characterization of the photonic crystal is often required, guiding the design process.…”

“…In Section 3 we focus on the photonic crystal microcavity that we have simulated. We have chosen a well-known system: a two-dimensional photonic crystal with a central defect [6]. The cavity is made of GaAs cylinders in air.…”

Fabrication and Characterization of GaP Photonic Crystals for Terahertz Wave Application

“…For the optical region, PCs have been utilized in waveguides, high-Q filters, lasers, and fibers. [27][28][29][30] In THz region, PCs are also of interest, as they could contribute to improvement of THz technology. Comparing to applications of passive devices such as filters, waveguides and PC fibers, there are few active devices.…”