Realization of “trapped rainbow” in 1D slab waveguide with surface dispersion engineering
journal contributionposted on 2016-09-12, 00:00 authored by Rui Yang, Wenkan Zhu, Jingjing Li
We present a design of a one dimensional dielectric waveguide that can trap a broadband light pulse with different frequency component stored at different positions, effectively forming a “trapped rainbow” [Nature 450, 397 (2007)]. The spectrum of the rainbow covers the whole visible range. To do this, we first show that the dispersion of a SiO2 waveguide with a Si grating placed on top can be engineered by the design parameter of the grating. Specifically, guided modes with zero group velocity(frozen modes) can be realized. Negative Goos-H¨anchen shift along the surface of the grating is responsible for such a dispersion control. The frequency of the frozen mode is tuned by changing the lateral feature parameters (period and duty cycle) of the grating. By tuning the grating feature point by point along the waveguide, a light pulse can be trapped with different frequency components frozen at different positions, so that a “rainbow” is formed. The device is expected to have extremely low ohmic loss because only dielectric materials are used. A planar geometry also promises much reduced fabrication difficulty.
The Research Open Access Publishing (ROAAP) Fund of the University of Illinois at Chicago provides part of the publication fee for the open access of this article.
Publisher StatementThis is a copy of an article published in the Optics Express. © 2015 Optical Society of America.
PublisherOptical Society of America