Manipulation of photons at the surface of three-dimensional photonic crystals

Abstract

In three-dimensional (3D) photonic crystals, refractive-index variations with a periodicity comparable to the wavelength of the light passing through the crystal give rise to so-called photonic bandgaps, which are analogous to electronic bandgaps for electrons moving in the periodic electrostatic potential of a material's crystal structure. Such 3D photonic bandgap crystals are envisioned to become fundamental building blocks for the control and manipulation of photons in optical circuits. So far, such schemes have been pursued by embedding artificial defects and light emitters inside the crystals, making use of 3D bandgap directional effects. Here we show experimentally that photons can be controlled and manipulated even at the 'surface' of 3D photonic crystals, where 3D periodicity is terminated, establishing a new and versatile route for photon manipulation. By making use of an evanescent-mode coupling technique, we demonstrate that 3D photonic crystals possess two-dimensional surface states, and we map their band structure. We show that photons can be confined and propagate through these two-dimensional surface states, and we realize their localization at arbitrary surface points by designing artificial surface-defect structures through the formation of a surface-mode gap. Surprisingly, the quality factors of the surface-defect mode are the largest reported for 3D photonic crystal nanocavities (Q up to approximately 9,000). In addition to providing a new approach for photon manipulation by photonic crystals, our findings are relevant for the generation and control of plasmon-polaritons in metals and the related surface photon physics. The absorption-free nature of the 3D photonic crystal surface may enable new sensing applications and provide routes for the realization of efficient light-matter interactions.

Bloch surface eigenstates within the radiation continuum

“…1,2 Such a state may exist if it cannot couple to any bulk state in the PhC or to any free-space mode in air; the bandgap of the PhC prohibits propagation, serving the same role as metals and negative-index materials in surface plasmon modes. 3 These PhC surface states have been observed experimentally, 4,5 and their localized properties have been applied to enhance light collimation 6,7 and to manipulate photons on defects of the surface. 5 It is often thought that bona fide photonic surface states can only exist below the light cone of the ambient air (i.e., below the continuum of radiation modes in air), where they are confined by total internal reflection.…”

“…3 These PhC surface states have been observed experimentally, 4,5 and their localized properties have been applied to enhance light collimation 6,7 and to manipulate photons on defects of the surface. 5 It is often thought that bona fide photonic surface states can only exist below the light cone of the ambient air (i.e., below the continuum of radiation modes in air), where they are confined by total internal reflection. We show that, under appropriate but general conditions, photonic surface states may also exist inside the radiation continuum.…”

Mapping the directional emission of quasi-two-dimensional photonic crystals of semiconductor nanowires using Fourier microscopy

“…These properties have been extensively studied to achieve control over the spontaneous light emission of nanophotonic sources. 2 PhCs have been proven to confine and manipulate light, 3,4 modify the density of optical states, 5,6 create high quality factor cavities leading to lasing, 7 and increase the outcoupling efficiency of light sources. [8][9][10] Semiconductor nanowires are potentially interesting building blocks for two dimensional (2D) PhCs.…”

Research Update: Strategies for efficient photoelectrochemical water splitting using metal oxide photoanodes

“…[40][41][42][43][44] Slow photons propagating with strongly reduced group velocity found in photonic crystals have an immense potential for increasing the path length of light. 45 Therefore, the photonic crystals can promote light absorption, resulting in photogenerated charge carriers.…”