80 research outputs found
A low-frequency chip-scale optomechanical oscillator with 58 kHz mechanical stiffening and more than 100th-order stable harmonics.
For the sensitive high-resolution force- and field-sensing applications, the large-mass microelectromechanical system (MEMS) and optomechanical cavity have been proposed to realize the sub-aN/Hz1/2 resolution levels. In view of the optomechanical cavity-based force- and field-sensors, the optomechanical coupling is the key parameter for achieving high sensitivity and resolution. Here we demonstrate a chip-scale optomechanical cavity with large mass which operates at ≈77.7 kHz fundamental mode and intrinsically exhibiting large optomechanical coupling of 44 GHz/nm or more, for both optical resonance modes. The mechanical stiffening range of ≈58 kHz and a more than 100th-order harmonics are obtained, with which the free-running frequency instability is lower than 10-6 at 100 ms integration time. Such results can be applied to further improve the sensing performance of the optomechanical inspired chip-scale sensors
Observations of Spontaneous Raman Scattering in Silicon Slow-light Photonic Crystal Waveguides
We report the observations of spontaneous Raman scattering in silicon
photonic crystal waveguides. Continuous-wave measurements of Stokes emission
for both wavelength and power dependence is reported in single line-defect
waveguides in hexagonal lattice photonic crystal silicon membranes. By
utilizing the Bragg gap edge dispersion of the TM-like mode for pump
enhancement and the TE-like fundamental mode-onset for Stokes enhancement, the
Stokes emission was observed to increase by up to five times in the region of
slow group velocity. The results show explicit nonlinear enhancement in a
silicon photonic crystal slow-light waveguide device.Comment: 12 pages, 4 figure
Nanometric precision distance metrology via chip-scale soliton microcombs
Laser interferometry serves a fundamental role in science and technology,
assisting precision metrology and dimensional length measurement. During the
past decade, laser frequency combs - a coherent optical-microwave frequency
ruler over a broad spectral range with traceability to time-frequency standards
- have contributed pivotal roles in laser dimensional metrology with
ever-growing demands in measurement precision. Here we report
spectrally-resolved laser dimensional metrology via a soliton frequency
microcomb, with nanometric-scale precision. Spectral interferometry provides
information on the optical time-of-flight signature, and the large
free-spectral range and high-coherence of the microcomb enables tooth-resolved
and high-visibility interferograms that can be directly readout with optical
spectrum instrumentation. We employ a hybrid timing signal from comb-line
homodyne interferometry and microcomb spectrally-resolved interferometry - all
from the same spectral interferogram. Our combined soliton and homodyne
architecture demonstrates a 3-nm repeatability achieved via homodyne
interferometry, and over 1,000-seconds stability in the long-term precision
metrology at the white noise limits.Comment: 24 pages, 12 figure
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
Surface plasmon enhanced responsivity in a waveguided germanium metal-semiconductor-metal photodetector
The authors report on high transverse magnetic (TM)-mode responsivity in a waveguided germaniumSchottky-barriermetal-semiconductor-metalphotodetector on silicon-on-insulator substrate for operating wavelength at 1550 nm. The employed aluminum interdigitated electrodes act as a one-dimensional rectangular grating above the depletion layer. By means of properly designed finger dimensions, surface plasmon polariton resonances can be excited at the interface of metal and silicon interfacial layer due to grating coupling. The resulting strong field intensities reach into active region, enabling high absorption under TM injection. At a voltage of 1 V, the TM-mode photocurrent is measured over three times than that of transverse electric mode, in spite of the relatively larger TM insertion loss in the silicon waveguide.This work is supported by Agency for Science,
Technology and Research A*STAR SERC Science and
Engineering Research Council Grant Programme SERC
Grant No. 092 154 0098, Singapore
- …