Nano-engineered tunable photonic crystals

Abstract

Photonic crystals offer a well-recognized ability to control the propagation of modes of light in an analogous fashion to the way in which nanostructures have been harnessed to control electron-based phenomena. This has led to proposals and indeed demonstrations of a wide variety of photonic-crystal-based photonic devices with applications in areas including communications, computing and sensing, for example. In such applications, photonic crystals can offer both a unique performance advantage, as well as the potential for substantial miniaturization of photonic systems. However, as this review outlines, two-dimensional (2-D) and three-dimensional (3-D) structures for the spectral region covering frequencies from the ultraviolet (UV) to the near-infrared (near-IRnear-infrared (near-IR)) (≈ 2 μm) are challenging to fabricate with appropriate precision, and in a cost-effective and also flexible way, using traditional methods. Naturally, a key concern is how amenable a given approach is to the intentional incorporation of selected defects into a particular structure. Beyond passive structures, attention turns to so-called active photonic crystals, in which the response of the photonic crystal to light can be externally changed or tuned. This capability has widespread potential in planar lightwave circuits for telecommunications, where it offers mechanisms for selective switching, for example. This review discusses alternative proposals for tuning of such photonic crystals.