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Self collimation in square lattice two dimensional photonic crystals with dielectric ring

QUAN XU1,* , KANG XIE1, HUAJUN YANG2, ZHIBO LI2

Affiliation

  1. College of Optoelectronic Information, University of Electronic Science and Technology of China, Sichuan Province, 610054, China
  2. College of Physical Electronics, University of Electronic Science and Technology of China, Sichuan Province, 610054, China

Abstract

The self collimation phenomena based on a new type of photonic crystals made of square lattice with dielectric ring is demonstrated. The plane wave expansion (PWE) method is used to get the three dimensional band diagram and equi-frequency of the second band which displays the self collimation phenomena for the structure we proposed in this paper. The collimation angle is mainly depending on the maximum flatness half width (MFHW) of the equi-frequency. Latterly, we investigated the relation of the MFHW, radius R and the width r for TM modes (only TM mode is referred in this paper) with the ring shaped holes structure. By further investigation, we know that with every r , the MFHW would get a maximum value for different R . Lastly, the FDTD method is employed to demonstrate the electric field amplitude distributions for the collimation phenomena. Partly, in order to achieve high efficient coupling of the input and output port, we modify both surface structures to modulate the wave-front to obtain desired effect. The parameter of the input surface is modified which will prevent the production of surface modes which takes away the EM power and enhance the transmittance. For a square lattice with the modified parameters at each side of the input surface, the surface modes are suppressed to couple with the continuum of the air modes. The parameters are R′ = 0.384R and r′ = 0.384r in the modified zone at the input and output. These self collimation based devices can be used to enhance the light coupling efficiency, narrow the beam divergence of micro-cavity laser over a large frequency range. More importantly, they might have potential application in integrated optical circuits..

Keywords

(9999.9999) Photonic crystals, (250.5300) Photonic integrated circuits, (130.3120) Integrated optics devices.

Citation

QUAN XU, KANG XIE, HUAJUN YANG, ZHIBO LI, Self collimation in square lattice two dimensional photonic crystals with dielectric ring, Optoelectronics and Advanced Materials - Rapid Communications, 4, 11, November 2010, pp.1639-1642 (2010).

Submitted at: April 14, 2010

Accepted at: Nov. 10, 2010