Manipulating light with strongly modulated photonic crystals

TLDR

Strongly modulated photonic crystals fabricated with advanced semiconductor nanofabrication have demonstrated novel optical properties. The paper aims to delineate how these crystals differ from other optical media and clarify their capabilities. The study examines light confinement, frequency dispersion, and spatial dispersion in these crystals and explores their applications. The crystals exhibit ultra‑strong confinement in a cubic‑wavelength volume, extreme slow light via dispersion control, and negative refraction enabling perfect imaging, while their enhanced light–matter interaction supports on‑chip all‑optical processing and adiabatic tuning for frequency conversion, optomechanics, photon memories, and photon pinning.

Abstract

Recently, strongly modulated photonic crystals, fabricated by the state-of-the-art semiconductor nanofabrication process, have realized various novel optical properties. This paper describes the way in which they differ from other optical media, and clarifies what they can do. In particular, three important issues are considered: light confinement, frequency dispersion and spatial dispersion. First, I describe the latest status and impact of ultra-strong light confinement in a wavelength-cubic volume achieved in photonic crystals. Second, the extreme reduction in the speed of light is reported, which was achieved as a result of frequency dispersion management. Third, strange negative refraction in photonic crystals is introduced, which results from their unique spatial dispersion, and it is clarified how this leads to perfect imaging. The last two sections are devoted to applications of these novel properties. First, I report the fact that strong light confinement and huge light–matter interaction enhancement make strongly modulated photonic crystals promising for on-chip all-optical processing, and present several examples including all-optical switches/memories and optical logics. As a second application, it is shown that the strong light confinement and slow light in strongly modulated photonic crystals enable the adiabatic tuning of light, which leads to various novel ways of controlling light, such as adiabatic frequency conversion, efficient optomechanics systems, photon memories and photons pinning.