Photonic Band Gap Structures
B. Harmon, K.-M. Ho, M. Sigalas, R. Biswas, C. Soukoulis, G. Tutle, K. Constant, D. Turner, and B. Vasiliu, Ames Laboratory/Iowa State University
Research Objective
Electromagnetic (EM) waves propagating through structures of periodically modulated dielectric constants are organized into photonic bands that are analogous to the electronic band structures in crystals. These photonic band gap (PBG) structures can be designed to affect EM waves in a variety of ways. Applying the power of massively parallel computers such as the Cray T3E at NERSC allows us to design and study a broad range of optical devices made from dielectric and metallic photonic crystals.
Computational Approach
We use two main methods to investigate PBG structures. With the Transfer Matrix Method (TMM), we can calculate the transmission and reflection coefficients of a plane wave incident on a PBG structure consisting of metals and/or dielectrics. With the Finite Difference Time Domain (FDTD) method, we can investigate the time-dependent effects of EM wave propagation through finite size systems. The power of the Cray T3E allows us to attack much larger problems involving a higher degree of disorder for both of these methods.
Accomplishments
The TMM code has been instrumental in allowing us to study defects in PBG materials and to investigate the effects of disordered states. With the FDTD code, we have simulated the transmission of light around a sharp corner made from defects in the PBG material, as pictured in the waveguide. We have also calculated the radiation patterns from dipole antennas on 3D photonic crystals, where the dielectric crystal acts as a perfectly reflecting substrate.
Significance
This work is allowing us to develop a more fundamental understanding of PBG structures, including the effects of defects and disordered states that are computationally very demanding. This understanding and the ability to simulate photonic structures on the Cray T3E at NERSC are allowing us to design and study a variety of optical devices, which we can then build and investigate experimentally.
Publications
M. M. Sigalas, R. Biswas, K. M. Ho, W. Leung, G. Tuttle, and D. Crouch, "Applications of photonic band gap materials," Proceedings of the 13th Annual Review of Progress in Applied Computational Electromagnetics (1997), p. 412.
Transmission of light around a sharp corner in a 3D PBG waveguide.
M. M. Sigalas, R. Biswas, K. M. Ho, C. M. Soukoulis, and D. D. Crouch, "Waveguides in photonic band gap materials," Proceedings of the 14th Annual Review of Progress in Applied Computational Electromagnetics (1998), p. 144.
M. M. Sigalas, R. Biswas, Q. Li, D. Crouch, W. Leung, R. Jacobs-Woodbury, B. Lough, S. Nielsen, S. McCalmont, G. Tuttle, and K. M. Ho, "Dipole antennas on photonic band gap crystals -- Experiment and simulations," Microwave and Optical Technology Letters 15, 153 (1997).