Effect of dielectric and magnetic contrast on the photonic band gap in ferrodispersion

R. V. Mehta - R. Patel - B. Chudasama - H. Desai - R. V. Upadhyay

Department of Physics, Bhavnagar University, Bhavnagar 364 002, India

Abstract
Magnetically induced photonic effects are studied using magnetic colloids, containing micron-sized magnetic spheres, and five different ferrofluids. Under transverse configuration of an applied magnetic field, a linearly polarized monochromatic light is inhibited at a critical value of the field. In the forward direction, the light beam remains inhibited for a certain interval of the field. Both the critical field and the `magnetic band gap' are found to be dependent on the refractive index contrast between the micron-sized magnetic particles and the ferrofluid. The critical field shifts towards a higher value and the band gap decreases as the contrast increases. Using a model of a magnetically tunable photonic medium, the results are analyzed. Tables 1, Figs 5, Refs 23.