75 research outputs found
Photonic Crystal Cavities in Silicon Dioxide
One dimensional nano-beam photonic crystal cavities fabricated in silicon
dioxide are considered in both simulation and experiment. Quality factors of
over 10^4 are found via simulation, while quality factors of over 5*10^3 are
found in experiment, for cavities with mode volumes of 2.0 cubic wavelengths
(in oxide) and in the visible wavelength range (600-716nm). The dependences of
the cavity quality factor and mode volume for different design parameters are
also considered.Comment: 4 pages, 3 figure
Plasmonic Enhancement of Emission from Si-nanocrystals
Plasmonic gratings of different periodicities are fabricated on top of
Silicon nanocrystals embedded in Silicon Dioxide. Purcell enhancements of up to
2 were observed, which matches the value from simulations. Plasmonic
enhancements are observed for the first three orders of the plasmonic modes,
with the peak enhancement wavelength varying with the periodicity. Biharmonic
gratings are also fabricated to extract the enhanced emission from the first
order plasmonic mode, resulting in enhancements with quality factors of up to
16.Comment: 4 pages, 5 figures added explanation of low purcell enhancement
updated figure
Photoluminescence from silicon dioxide photonic crystal cavities with embedded silicon nanocrystals
One dimensional nanobeam photonic crystal cavities are fabricated in silicon
dioxide with silicon nanocrystals. Quality factors of over 9 x 10^3 are found
in experiment, matching theoretical predictions, with mode volumes of
1.5(lambda/n)^3 . Photoluminescence from the cavity modes is observed in the
visible wavelength range 600-820 nm. Studies of the lossy characteristics of
the cavities are conducted at varying temperatures and pump powers. Free
carrier absorption effects are found to be significant at pump powers as low as
a few hundred nanowatts.Comment: 13 pages 9 figure
Enhanced Light Emission from Erbium Doped Silicon Nitride in Plasmonic Metal-Insulator-Metal Structures
Plasmonic gratings and nano-particle arrays in a metal-insulator-metal
structures are fabricated on an erbium doped silicon nitride layer. This
material system enables simple fabrication of the structure, since the active
nitride layer can be directly grown on metal. Enhancement of collected emission
of up to 12 is observed on resonance, while broad off-resonant enhancement is
also present. The output polarization behavior of the gratings and
nano-particle arrays is investigated and matched to plasmonic resonances, and
the behavior of coupled modes as a function of inter-particle distance is also
discussed.Comment: 9 pages, 6 figures updated because pdf was still non-functiona
Observation of Transparency of Erbium-doped Silicon nitride in photonic crystal nanobeam cavities
One-dimensional nanobeam photonic crystal cavities are fabricated in an
Er-doped amorphous silicon nitride layer. Photoluminescence from the cavities
around 1.54 um is studied at cryogenic and room temperatures at different
optical pump powers. The resonators demonstrate Purcell enhanced absorption and
emission rates, also confirmed by time-resolved measurements. Resonances
exhibit linewidth narrowing with pump power, signifying absorption bleaching
and the onset of stimulated emission in the material at both 5.5 K and room
temperature. We estimate from the cavity linewidths that Er has been pumped to
transparency at the cavity resonance wavelength.Comment: 10 pages, 7 figure
Coupled fiber taper extraction of 1.53 um photoluminescence from erbium doped silicon nitride photonic crystal cavities
Optical fiber tapers are used to collect photoluminescence emission at ~1.5
um from photonic crystal cavities fabricated in erbium doped silicon nitride on
silicon. Photoluminescence collection via fiber taper is enhanced 2.5 times
relative to free space, with a total taper collection efficiency of 53%. By
varying the fiber taper offset from the cavity, a broad tuning range of
coupling strength is obtained. This material system combined with fiber taper
collection is promising for building on-chip optical amplifiers.Comment: 10 pages, 7 figure
Nanobeam photonic crystal cavity quantum dot laser
The lasing behavior of one dimensional GaAs nanobeam cavities with embedded
InAs quantum dots is studied at room temperature. Lasing is observed throughout
the quantum dot PL spectrum, and the wavelength dependence of the threshold is
calculated. We study the cavity lasers under both 780 nm and 980 nm pump,
finding thresholds as low as 0.3 uW and 19 uW for the two pump wavelengths,
respectively. Finally, the nanobeam cavity laser wavelengths are tuned by up to
7 nm by employing a fiber taper in near proximity to the cavities. The fiber
taper is used both to efficiently pump the cavity and collect the cavity
emission.Comment: 8 pages; 6 figure
Low Power Resonant Optical Excitation of an Optomechanical Cavity
We demonstrate the actuation of a double beam opto-mechanical cavity with a
sinusoidally varying optical input power. We observe the driven mechanical
motion with only 200 nW coupled to the optical cavity mode. We also investigate
the pump power dependence of the radio-frequency response for both the driving
power and the probe power. Finally, we investigate the dependence of the
amplitude of the mechanical motion on mechanical cavity quality factor.Comment: 11 pages, 6 figure
A longitudinal resource for population neuroscience of school-age children and adolescents in China
During the past decade, cognitive neuroscience has been calling for population diversity to address the challenge of validity and generalizability, ushering in a new era of population neuroscience. The developing Chinese Color Nest Project (devCCNP, 2013–2022), the first ten-year stage of the lifespan CCNP (2013–2032), is a two-stages project focusing on brain-mind development. The project aims to create and share a large-scale, longitudinal and multimodal dataset of typically developing children and adolescents (ages 6.0–17.9 at enrolment) in the Chinese population. The devCCNP houses not only phenotypes measured by demographic, biophysical, psychological and behavioural, cognitive, affective, and ocular-tracking assessments but also neurotypes measured with magnetic resonance imaging (MRI) of brain morphometry, resting-state function, naturalistic viewing function and diffusion structure. This Data Descriptor introduces the first data release of devCCNP including a total of 864 visits from 479 participants. Herein, we provided details of the experimental design, sampling strategies, and technical validation of the devCCNP resource. We demonstrate and discuss the potential of a multicohort longitudinal design to depict normative brain growth curves from the perspective of developmental population neuroscience. The devCCNP resource is shared as part of the “Chinese Data-sharing Warehouse for In-vivo Imaging Brain” in the Chinese Color Nest Project (CCNP) – Lifespan Brain-Mind Development Data Community (https://ccnp.scidb.cn) at the Science Data Bank
Real-time Monitoring for the Next Core-Collapse Supernova in JUNO
Core-collapse supernova (CCSN) is one of the most energetic astrophysical
events in the Universe. The early and prompt detection of neutrinos before
(pre-SN) and during the SN burst is a unique opportunity to realize the
multi-messenger observation of the CCSN events. In this work, we describe the
monitoring concept and present the sensitivity of the system to the pre-SN and
SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is
a 20 kton liquid scintillator detector under construction in South China. The
real-time monitoring system is designed with both the prompt monitors on the
electronic board and online monitors at the data acquisition stage, in order to
ensure both the alert speed and alert coverage of progenitor stars. By assuming
a false alert rate of 1 per year, this monitoring system can be sensitive to
the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos
up to about 370 (360) kpc for a progenitor mass of 30 for the case
of normal (inverted) mass ordering. The pointing ability of the CCSN is
evaluated by using the accumulated event anisotropy of the inverse beta decay
interactions from pre-SN or SN neutrinos, which, along with the early alert,
can play important roles for the followup multi-messenger observations of the
next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure
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