31 research outputs found
Near-infrared Hong-Ou-Mandel interference on a silicon quantum photonic circuit
Near-infrared Hong-Ou-Mandel quantum interference is observed in silicon
nanophotonic directional couplers with raw visibilities on-chip at 90.5%.
Spectrally-bright 1557-nm two-photon states are generated in a
periodically-poled KTiOPO4 waveguide chip, serving as the entangled photon
source and pumped with a self-injection locked laser, for the photon
statistical measurements. Efficient four-port coupling in the communications
C-band and in the high-index-contrast silicon photonics platform is
demonstrated, with matching theoretical predictions of the quantum interference
visibility. Constituents for the residual quantum visibility imperfection are
examined, supported with theoretical analysis of the sequentially-triggered
multipair biphoton contribution and techniques for visibility compensation,
towards scalable high-bitrate quantum information processing and
communications.Comment: 15 pages, 6 figure
Parametric Optomechanical Oscillations in Two-Dimensional Slot-Type High-Q Photonic Crystal Cavities
We experimentally demonstrate an optomechanical cavity based on an air-slot
photonic crystal cavity with optical quality factor Qo=4.2\times10^4 and a
small modal volume of 0.05 cubic wavelengths. The optical mode is coupled with
the in-plane mechanical modes with frequencies up to hundreds of MHz. The
fundamental mechanical mode shows a frequency of 65 MHz and a mechanical
quality factor of 376. The optical spring effect, optical damping and
amplification are observed with a large experimental optomechanical coupling
rate gom/2pi of 154 GHz/nm, corresponding to a vacuum optomechanical coupling
rate g*/2pi of 707 kHz. With sub-mW or less input power levels, the cavity
exhibits strong parametric oscillations. The phase noise of the photonic
crystal optomechanical oscillator is also measured
Demonstration of an air-slot mode-gap confined photonic crystal slab nanocavity with ultrasmall mode volumes
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.Comment: 12 pages, 4 figure
High-reflectivity, high-Q micromechanical membranes via guided resonances for enhanced optomechanical coupling
Using Fano-type guided resonances (GRs) in photonic crystal (PhC) slab
structures, we numerically and experimentally demonstrate optical reflectivity
enhancement of high-Q SiNx membrane-type resonators used in
membrane-in-the-middle optomechanical (OM) systems. Normal-incidence
transmission and mechanical ringdown measurements of 50-nm-thick PhC membranes
demonstrate GRs near 1064 nm, leading to a ~ 4\times increase in reflectivity
while preserving high mechanical Q factors of up to ~ 5 \times 10^6. The
results would allow improvement of membrane-in-the-middle OM systems by virtue
of increased OM coupling, presenting a path towards ground state cooling of
such a membrane and observations of related quantum effects