2D Photonic Crystal Nanocavity Research Articles

Mode analysis of GaN two-dimensional photonic crystal nanocavities undercut by photo-electrochemical etching

GaN two-dimensional (2D) photonic crystal nanocavities with a single embedded InGaN quantum well are undercut by photo-electrochemical (PEC) etching and optically characterized to investigate the fundamental mode. The PEC etching selectively removes an InGaN-based sacrificial layer to form air-suspended GaN photonic crystal cavity slabs. We investigated the resonant modes of the photonic crystal nanocavities by micro-photoluminescence spectroscopy measurement at room temperature. The wavelengths of the measured resonant peaks and their dependence on the photonic crystal period agreed well with numerical analysis, allowing us to determine the fundamental mode in the measured spectra. The highest quality factor for the fundamental mode reached 3400 at blue wavelengths. This work would contribute to the improvement of GaN 2D photonic crystal nanocavities using PEC etching as well as their applications towards integrated light sources in visible wavelengths.

Optical coupling between atomically thin black phosphorus and a two dimensional photonic crystal nanocavity

Atomically thin black phosphorus (BP) is an emerging two dimensional (2D) material exhibiting bright photoluminescence in the near infrared region. Coupling its radiation to photonic nanostructures will be an important step toward the realization of 2D material based nanophotonic devices that operate efficiently in the near infrared region, which includes the technologically important optical telecommunication wavelength bands. In this letter, we demonstrate the optical coupling between atomically thin BP and a 2D photonic crystal nanocavity. We employed a home-build dry transfer apparatus for placing a thin BP flake on the surface of the nanocavity. Their optical coupling was analyzed through measuring cavity mode emission under optical carrier injection at room temperature.

Enhancement of a nano cavity lifetime by induced slow light and nonlinear dispersions

We start from a 2D photonic crystal nanocavity with moderate Q-factor and dynamically increase it by two order of magnitude by the joint action of coherent population oscillations and nonlinear refractive index.

2D Nonlinear Photonic Crystals Nanocavities in Chalcogenide for All-optical Processing

We demonstrate that high-Q nanocavity mode in 2D photonic crystal made in highly nonlinear chalcogenide glass can be excited using evanescent coupling from a tapered optical flbre. This scheme provides a promising platform to realize low power integrated all- optical switching and logic functions. The key to all-optical processing is the ability to enhance nonlinear efiects. One approach is based on developing optical conflgurations in which nonlinear efiects in a weakly nonlinear material are enhanced by reducing the mode size and increasing the intensity of the light wave. 2D photonic crystal (PhC) membranes are expected to play a key role in this context. It has been shown that ultra small and high quality factor Q can be created by introducing a carefully designed defect in the PhC (1). Following those advances, there have been predictions of the possibility of light switching light using nonlinear compact PhC microcavities operating at power levels of only a few mW (2,3). Chalcogenide glasses are attractive materials for all-optical signal processing. These glasses are composed of heavy elements including the chalcogens: S, Se and Te. The refractive index of chalcogenide is high, typically between 2.4 and 3.0 allowing 2D PhC slab to be created. Absorption losses are low over a wide wavelength range (near- to mid-infrared). Chalcogenide glasses possess a relatively large third-order optical nonlinearity (100{1000 times that of silica), and low two- photon absorption. In addition to reducing the switching power requirements, the pure Kerr-like nonlinearities ofier the potential for near instantaneous response times (< 100fs) and are only limited by the resonator Q-factor. Using chalcogenide glasses to fabricate a 2D PhC nanocavity which conflnes light at the wave- length scale and thus enhances the nonlinear light-material interaction provides the essential in- gredients for all-optical ultra-fast switching at low powers. It is well known that such cavities can exhibit optical bistability at incident powers that scale as the inverse square of the cavity's quality factor: 1/Q 2 . It is also well known that the minimum fractional nonlinear change in the refractive index, -n/n, needed to operate the device has to be greater than the inverse of the cavity's quality factor 1/Q. A common characteristic with glasses is that an upper bound exists on the nonlinear index change, -n, of a few 10 i4 . This implies that a minimum Q-factor exists of about 5,000 in order to observe a nonlinear switching. In addition, a strong resonance depth is required to obtain high contrast between the two switching states. Using PhC nanocavities ofier the advantage to strongly localize the mode in a small volume while limiting radiation losses through careful design (Fig. 1).