Scaling two-dimensional photonic crystals for transformation optics

Area of Science:

• * Photonics and Materials Science
• * Wave phenomena in engineered structures

Background:

• * Conventional transformation optics often relies on effective medium theory, which can be challenging for certain material properties like high anisotropy.
• * Achieving transformation optical devices with low refractive indices and specific anisotropic properties is a significant challenge.

Purpose of the Study:

• * To propose a new method for manipulating Bloch waves in curved photonic crystals.
• * To enable the design of two-dimensional transformation optical devices using only dielectric materials.
• * To overcome limitations of the conventional effective medium approach for specific optical properties.

Main Methods:

• * Transforming regular photonic crystals into curved configurations in physical space.
• * Establishing a scaling law to construct curved photonic crystals with similar unit cells but varying scales.
• * Utilizing only dielectric materials with refractive indices ranging from 1 to 4.

Main Results:

• * Successfully designed a wave compressor and a bending waveguide using the proposed method.
• * Demonstrated the feasibility of creating transformation optical devices with low-index dielectric materials.
• * The method allows for the construction of curved photonic crystals with tunable properties.

Conclusions:

• * The proposed method offers a viable route for fabricating low-loss transformation media.
• * It is particularly useful for achieving large anisotropy, which is difficult with conventional methods, especially for E-polarization.
• * This technique advances the design of novel optical devices through physical space transformation of photonic crystals.