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A quartz-enhanced photoacoustic spectroscopy based gas sensor was optimized to improve its compact spectrophone design and performance. The impact of a 2-tube microresonator geometry on the detected signal and signal to noise ratio (SNR) was investigated. Experimental studies demonstrate that the l=4.4 mm long tubes (ID=0.5 mm) result in a significantly enhanced SNR.
A method for thermal-stabilization of silicon microdisk resonators, based on thermooptic polymer coatings, is proposed. Two orders of magnitude improvement in thermal stability is expected. Effects on Q and major fabrication challenges are discussed.
We developed a new approach to fabricate high-quality single-crystalline high-index-contrast waveguiding micro- and nanostructures and demonstrated electro-optic modulation at 1.55 mum in waveguides grown from the melt of a recently developed organic material.
We experimentally demonstrate a picogram-scale optomechanical system that increases its mechanical rigidity by more than 5times with the application of mW-level optical power. We discuss the theory and fabrication, making comparisons to existing optomechanical systems.
We demonstrate a fast integrated germanium photodetector above 40 GHz and its integration with a silicon microring resonator-based wavelength division demultiplexer.
We demonstrate a very simple technique to fabricate robust micro bottle resonators. Spheroidal WGMs and bottle modes were excited preferentially using a tapered fiber coupled at specific locations along the bottle, and characteristic resonance spectra obtained.
A simple chemical method for reducing free-carrier lifetime in silicon photonics while maintaining low optical loss is presented. Lifetimes of ~ 300 ps for optical losses of ~ 0.4 cm-1 are achieved. Ramifications for nonlinear optics are discussed.
We show that evanescent fields of microresonators can be employed for cavity-enhanced high-sensitivity monitoring of nanomechanical motion. This novel scheme opens the path to observing backaction effects using optical gradient forces in the resolved-sideband regime.
An exposed Bragg grating incorporated into a planar waveguide was used to form a refractive index sensor. The high sensitivity to subtle changes allowed the study of surface functionalisation and binding within a microfluidic system.
Design of a simple doubly clamped cantilever structure capable of localizing mechanical and optical energy at the nanoscale is presented. The optical design is based upon photonic crystal concepts in which simple nanoscale patterning of a sub-micron cross-section cantilever can result in strong optical localization to an effective optical mode volume of 4 cubic wavelengths in the material (4(lambda/n)...
A new class of microphotonic-resonators, Adiabatic Resonant Microrings (ARMs), is introduced. The ARM resonator geometry enables heater elements to be formed within the resonator, simultaneously enabling record low-power (4.4 W/GHz) and record high-speed (1 mus) thermal tuning.
A new model is developed for the effects of the Kerr optical nonlinearity in a microring (racetrack) resonator coupled to input and output waveguides, which takes into account the nonlinearity in the couplers as well as the microring sections, as well as two-photon absorption, in the silicon-on-insulator platform. The switching intensity is 30 dB lower than predicted by existing models which assume...
We demonstrate a ~2.6 mm-diameter optical ring resonator fabricated from a 7.2 mum-thick silica fiber with a CO2 laser-fused coupling region for mechanical robustness. We experimentally obtain a Q-factor of ges25,000 at 1.55 mum.
A novel method for contouring of optical surfaces with unprecedented dynamic range is presented. At an object depth >50 mum, surface deformations of a MEMS of some 10 nm are still unambiguously detectable.
We demonstrate giant opto-mechanical oscillations in a silica double-disk where the optical gradient force creates dramatic dynamic back action in comparison to radiation pressure.
We experimentally observe an opto-mechanical whispering-gallery [WG] resonator vibrating at 11 GHz. We use optical electrostriction to drive mechanical vibration at frequencies which scale inversely with optical wavelength, irrespective of micro-resonator size.
Resonator-based filters using oxide-clad silicon microdisks scaled to ultimate miniaturization (radius~1.5-2 mum) close to radiation limit are demonstrated. High-Q (~1.5times105) and single-mode operation in each microdisk enables low insertion-loss and large free-spectral-range filters.
We theoretically and experimentally demonstrate that thermal effect in ultra-high-Q silica toroidal microresonators can be compensated by applying a layer of polydimethylsiloxane (PDMS). The observed Q factor is 1.5times106 for coating thickness of 0.52 mum.
Despite of wide range of potential applications, 3D functional microparticles with nanostructures cannot be prepared readily by conventional synthetic schemes. Here, we will consider two different routes for the microparticles: namely, self-organization of photo-responsive complex colloids inside microfluidic devices and holographic lithography directly on pre-patterned microfluidic channels. The...
Femtosecond-laser-written waveguides were integrated with fluidic microchannels in a commercial lab-on-a-chip. High-spatial-resolution monitoring of fluorescently labeled DNA molecules during capillary electrophoresis separation is demonstrated, as an intermediate step toward point-of-care diagnostic bioassays for DNA analysis.
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