Demonstration of an air-slot mode-gap confined photonic crystal slab nanocavity with ultrasmall mode volumes

Abstract

Abstract:We demonstrate experimentally an air-slot mode-gap photonic crystal cavity with quality factor of 15,000 and modal volume of 0.02 cubic wavelengths, based on the design of an air-slot in a width-modulated line-defect in a photonic crystal slab. The origin of the high Q air-slot cavity mode is the mode-gap effect from the slotted photonic crystal waveguide mode with negative dispersion. The high Q cavities with ultrasmall mode volume are important for applications such as cavity quantum electrodynamics, nonlinear optics and optical sensing.

Optomechanics in an ultrahigh-Q two-dimensional photonic crystal cavity

“…A narrowband optical transmission spectrum ͑calibrated using a fiber Mach-Zender interferometer͒ for one such device is shown in the inset of Fig. 3͑a͒, with a measured intrinsic optical Q i = 1.2ϫ 10 6 .…”

“…The photodetected signal is sent to an oscilloscope ͑2 GHz bandwidth͒ where the electronic power spectral density ͑PSD͒ is computed. An ex- 6 . ͑b͒ rf-PSD of the photodetected signal, indicating a series of resonance peaks corresponding to mechanical motion of the patterned slab.…”

“…[9][10][11] Applying this same design principle to slotted photonic crystal waveguides, 12 optical cavities with Q Յ 5 ϫ 10 4 have been experimentally demonstrated. 5,6 A major source of optical loss in real fabricated structures is light scattering out of the plane of the slab. One class of optical states which play an important role in determining scattering loss are the resonant leaky modes of the slab.…”

“…5 They have also more recently been studied in the context of Purcell enhancement of spontaneous emission from embedded quantum dots. 6 In the canonical optomechanical system, consisting of a Fabry-Perot resonator with an oscillating end-mirror, 7 the radiation pressure force per cavity photon is given by បgwhere o is the cavity resonance frequency, x is the position of the end mirror, and L OM is approximately equal to the physical length of the cavity. In the quantum realm, one is interested in the zero-point motion coupling rate, which is given by g = g OM ͱ ប / 2m eff m , where m eff is the effective motional mass and m is the mechanical resonance frequency.…”

“…5 They have also more recently been studied in the context of Purcell enhancement of spontaneous emission from embedded quantum dots. 6 In the canonical optomechanical system, consisting of a Fabry-Perot resonator with an oscillating end-mirror, 7 the radiation pressure force per cavity photon is given by បg…”