- Jan 2019-March 2019, Open-Ended Lab at NISER
- Guide: Dr. Ritwick Das, NISER (currently at IIT Delhi)
The reflectivity of a stratified media with a spatially periodic refractive index is analogous to the allowed energy bands of a periodic potential. Similarly, the optical analogy to the Tamm plasmon state in condensed matter physics is the electric eld distribution of electromagnetic wave of a particular wavelength which is localized at the interface of a metal and photonic crystal. It is characterized by high absorption and lower reflectivity and transmissivity.
We report the computational principle and methodology to simulate the same. Written in python, the program is designed to compute the electric spectrum give a Photonic Crystal (PhC). The program is well documented and is named “\DBR Spectra”. We present the computational results spectrum of a given DBR and the eld intensity distribution for different wavelengths. The Tamm state and its intensity distribution were determined by simulating a metal layer on the DBR. The Tamm resonance
wavelength decreases with increase in the thickness of the metal coating. The same qualitative trend is observed in the case of increasing the angle of incidence.
To demonstrate the usefulness of the program DBR spectra, the spectrum of a photonic crystal was experimentally obtained and was fitted with the simulated one so as to characterize the Photonic Crystal. Tamm state was obtained for a metal coated DBR and the variation of its wavelength with the angle of incidence was observed. The future experimental and computational plan for further exploration has been briefly outlined.