Optical design of split-beam photonic crystal nanocavities

We design high quality factor photonic crystal nanobeam cavities formed by two mechanically isolated cantilevers. These "split-beam" cavities have a physical gap at the center, allowing mechanical excitations of one or both of the cavity halves. They are designed by analyzing the optical band structures and mode profiles of waveguides perforated by elliptical holes and rectangular gaps, and are predicted to support optical resonances with quality factors exceeding 1E6 at wavelengths of ~ 1.6 um.Comment: To appear in Optics Letter

Efficient input and output fiber coupling to a photonic crystal waveguide

The efficiency of evanescent coupling between a silica optical fiber taper and a silicon photonic crystal waveguide is studied. A high reflectivity mirror on the end of the photonic crystal waveguide is used to recollect, in the backwards propagating fiber mode, the optical power that is initially coupled into the photonic crystal waveguide. An outcoupled power in the backward propagating fiber mode of 88% of the input power is measured, corresponding to a lower bound on the coupler efficiency of 94%

Fabrication-tolerant high quality factor photonic crystal microcavities

A two-dimensional photonic crystal microcavity design supporting a wavelength-scale volume resonant mode with a calculated quality factor (Q) insensitive to deviations in the cavity geometry at the level of Q~2x10^4 is presented. The robustness of the cavity design is confirmed by optical fiber-based measurements of passive cavities fabricated in silicon. For microcavities operating in the lambda = 1500 nm wavelength band, quality factors between 1.3-4.0x10^4 are measured for significant variations in cavity geometry and for resonant mode normalized frequencies shifted by as much as 10% of the nominal value.Comment: 3 pages, 3 figure

Evanescent coupling from optical fiber tapers to photonic crystal waveguides and resonators

Using a coupled mode theory and finite-difference time-domain calculations nearly complete evanescent power transfer between a fiber taper and a photonic crystal defect waveguide which is ideal for probing high-Q cavities is predicted

Nonlinear absorption and dispersion in fiber coupled silicon photonic crystal microresonators

Two-photon absorption, free-carrier absorption and dispersion, and thermo-optic dispersion in high-Q, ultra-small mode volume, photonic crystal cavities are studied experimentally. Sub-nanosecond free-carrier lifetimes, and optical bistability at ∼ 100μW cavity input power are observed

Design of high-Q photonic crystal optical cavities through Fourier space methods

By describing radiation losses through a Fourier space picture of modal couplings, low loss photonic crystal cavities are designed using a group theory-based analysis and finite difference time domain calculations, resulting in predicted quality factors exceeding 10^5

Cavity optomechanics in gallium phosphide microdisks

We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors $> 2.8\times10^{5}$ and mode volumes $< 10 (\lambda/n)^3$, and study their nonlinear and optomechanical properties. For optical intensities up to $8.0\times10^4$ intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two-photon absorption is not significant. We observe optomechanical coupling between optical modes of the microdisk around 1.5 $\mu$m and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate $g_0/2\pi \sim 30$ kHz for the fundamental mechanical radial breathing mode at 488 MHz.Comment: Published Versio