Micromechanical resonator driven by radiation pressure force

Radiation pressure exerted by light on any surface is the pressure generated by the momentum of impinging photons. The associated force - fundamentally, a quantum mechanical aspect of light - is usually too small to be useful, except in large-scale problems in astronomy and astrodynamics. In atomic and molecular optics, radiation pressure can be used to trap or cool atoms and ions. Use of radiation pressure on larger objects such as micromechanical resonators has been so far limited to its coupling to an acoustic mode, sideband cooling, or levitation of microscopic objects. In this Letter, we demonstrate direct actuation of a radio-frequency micromechanical plate-type resonator by the radiation pressure force generated by a standard laser diode at room temperature. Using two independent methods, the magnitude of the resonator's response to forcing by radiation pressure is found to be proportional to the intensity of the incident light.https://www.nature.com/articles/s41598-017-16063-4.epdfPublished versio

Perspective: Melanoma diagnosis and monitoring: Sunrise for melanoma therapy but early detection remains in the shade

Last revised 25 Jul 2016.Melanoma is one of the most dangerous forms of cancer. The five-year survival rate is 98% if it is detected early. However, this rate plummets to 63% for regional disease and 17% when tumors have metastasized, that is, spread to distant sites. Furthermore, the incidence of melanoma has been rising by about 3% per year, whereas the incidence of cancers that are more common is decreasing. A handful of targeted therapies have recently become available that have finally shown real promise for treatment, but for reasons that remain unclear only a fraction of patients respond long term. These drugs often increase survival by only a few months in metastatic patient groups before relapse occurs. More effective treatment may be possible if a diagnosis can be made when the tumor burden is still low. Here, an overview of the current state-of-the-art is provided along with an argument for newer technologies towards early point-of-care diagnosis of melanoma

Optical Wireless Information Transfer with Nonlinear Micromechanical Resonators

Wireless transfer of information is the basis of modern communication. It includes cellular, WiFi, Bluetooth and GPS systems, all of which use electromagnetic radio waves with frequencies ranging from typically 100 MHz to a few GHz. However, several long-standing challenges with standard radio-wave wireless transmission still exist, including keeping secure transmission of data from potential compromise. Here, we demonstrate wireless information transfer using a line-of-sight optical architecture with a micromechanical element. In this fundamentally new approach, a laser beam encoded with information impinges on a nonlinear micromechanical resonator located a distance from the laser. The force generated by the radiation pressure of the laser light on the nonlinear micromechanical resonator produces a sideband modulation signal, which carries the precise information encoded in the subtle changes in the radiation pressure. Using this, we demonstrate data and image transfer with one hundred percent fidelity with a single 96 micron by 270 micron silicon resonator element in an optical frequency band. This mechanical approach relies only on the momentum of the incident photons and is therefore able to use any portion of the optical frequency banda band that is 10,000 times wider than the radio frequency band. Our line-of-sight architecture using highly scalable micromechanical resonators offers new possibilities in wireless communication. Due to their small size, these resonators can be easily arrayed while maintaining a small form factor to provide redundancy and parallelism.Comment: 6 pages, 4 figure

Measurement of nonlinear piezoelectric coefficients using a micromechanical resonator

We describe and demonstrate a method by which the nonlinear piezoelectric properties of a piezoelectric material may be measured by detecting the force that it applies on a suspended micromechanical resonator at one of its mechanical resonance frequencies. Resonators are used in countless applications; this method could provide a means for better-characterizing material behaviors within real MEMS devices. Further, special devices can be designed to probe this nonlinear behavior at specific frequencies with enhanced signal sizes. The resonators used for this experiment are actuated using a 1-μm-thick layer of aluminum nitride. When driven at large amplitudes, the piezoelectric layer generates harmonics, which are measurable in the response of the resonator. In this experiment, we measured the second-order piezoelectric coefficient of aluminum nitride to be −(23.1±14.1)×10^−22m/V^2.Published versio

Micromechanical resonator with dielectric nonlinearity

Nonlinear response of dielectric polarization to electric field in certain media is the foundation of nonlinear optics. Optically, such nonlinearities are observed at high light intensities, achievable by laser, where atomic-scale field strengths exceeding 106–108 V/m can be realized. Nonlinear optics includes a host of fascinating phenomena such as higher harmonic frequency generation, sum and difference frequency generation, four-wave mixing, self-focusing, optical phase conjugation, and optical rectification. Even though nonlinear optics has been studied for more than five decades, such studies in analogous acoustic or microwave frequency ranges are yet to be realized. Here, we demonstrate a nonlinear dielectric resonator composed of a silicon micromechanical resonator with an aluminum nitride piezoelectric layer, a material known to have a nonlinear optical susceptibility. Using a novel multiport approach, we demonstrate second and third-harmonic generation, sum and difference frequency generation, and four-wave mixing. Our demonstration of a nonlinear dielectric resonator opens up unprecedented possibilities for exploring nonlinear dielectric effects in engineered structures with an equally broad range of effects such as those observed in nonlinear optics. Furthermore, integration of a nonlinear dielectric layer on a chip-scale silicon micromechanical resonator offers tantalizing prospects for novel applications, such as ultra high harmonic generation, frequency multipliers, microwave frequency-comb generators, and nonlinear microwave signal processing.Published versio