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Photonic crystals resonant cavities. Quality factors

B. LAZĂR1, P. STERIAN1,*

Affiliation

  1. Bucharest Polytechnic University, Academic Center for Optical Engineering and Photonics, 77206 Bucharest, Romania

Abstract

The essential property of photonic crystals, namely their capacity to forbid the propagation of electromagnetic field in all directions, leads immediately to the idea of building tiny resonant cavities having high quality factors [3-14]. Such resonators, with well controlled frequencies and life times, can be used, together with photonic guides, at the construction of various active and passive optical devices like: lasers, filters, demultiplexors, splitters, etc. In general, photonic resonators are built by introducing a defect in the perfect crystal. Usually, such inhomogeneities admit one or more resonances whose frequencies can be adjusted to fall inside one of the forbidden bands of the perfect crystal. If the cavity is surrounded by many layers, formed by elementary crystal cells, then there is no way for the field to go to and the quality factor, Q, tends to infinity. For walls of finite size, Q has limited values. What is desired are resonators as small as possible with Q as large as possible. The main goal of the current paper is to analyze, using FDTD (Finite Difference Time Domain) method, the structures of modes (field maps, resonant frequencies and quality factors) corresponding to some cavities, build in a photonic crystal with square symmetry..

Keywords

Photonic crystal, Resonant cavity, Quality factor, Square symmetryFinite Difference Time Domain (FDTD) method.

Submitted at: Sept. 24, 2007
Accepted at: Jan. 18, 2008

Citation

B. LAZĂR, P. STERIAN, Photonic crystals resonant cavities. Quality factors, Journal of Optoelectronics and Advanced Materials Vol. 10, Iss. 1, pp. 44-54 (2008)