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

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

COMPARATIVE EDUCATION WITH HISTORICAL SOCIOLOGY: A STUDY OF MATHEMATICS EDUCATION OF CANADA AND PAKISTAN

The recent curricular reforms in mathematics education in Punjab, Pakistan and Ontario, Canada are studied in this work. The countries are first studied individually and then compared against each other. Using historical sociology, differences between traditional and modern education as well as the underlying theories of mathematics learning are incorporated to explain the shifts in the mathematics curricula in both the cases. We also discuss the various aspects of shifts in learning theories as mainly a tension between the traditional and progressive modes of learning. In the case of Punjab, Pakistan, it is found that the revised reform documents as well as the mathematics textbooks, do not displace the traditional views of learning mathematics as passive reception, rote memorization and reproduction of textbook questions in assessment. In the case of Ontario, Canada, shifts in Ontario mathematics curricular reforms over a decade (1995-2005) indicate adjustment and implementation towards newer learning theories based upon constructivism. This shift is claimed to be based on the 1989 NCTM reforms in the USA. This learning theory shifted considerably in the 1997 document, which is argued to be a mixture of traditionalist skill-based mathematics and the newer problem-solving based constructivist approach. The latest 2005 curriculum document, however, firmly re-focuses on problem-solving as a central feature as well as placing substantial emphasis on “mathematical processes” like communication and information technology for learning and teaching mathematics. Keywords: Mathematics Education, Comparative Education, Historical Sociology, and Curriculum Studies

Micromechanical microphone using sideband modulation of nonlinear resonators

We report the successful detection of an audio signal via sideband modulation of a nonlinear piezoelectric micromechanical resonator. The 270$\times$96-$\mu$m resonator was shown to be reliable in audio detection for sound intensity levels as low as ambient room noise and to have an unamplified sensitivity of 23.9 $\mu$V/Pa. Such an approach may be adapted in acoustic sensors and microphones for consumer electronics or medical equipment such as hearing aids.Comment: 5 pages, 3 figure

Development of a global model for atmospheric backscatter at CO2 wavelengths

The effect of aerosol microphysical processes on the backscatter from an aerosol plume undergoing long-range atmospheric transport was studied. A numerical model which examines the effects of coagulation and sedimentation on an aerosol size distribution is under development and the initial results for a single homogeneous layer were obtained. Use was made of the SAGE/SAM II data set to study the global variation of aerosol concentration and, hence, to predict the variation of Beta sub CO2. Computer programs were written to determine the mean, median, and the probability distribution of the measured aerosol extinction as a function of altitude, latitude and geographical conditions. The first data sets analyzed in this way are under study. Data was used to study aerosol behavior over the U.S.A. and the Pacific Ocean

SAGE 1 and SAM 2 measurements of 1 micron aerosol extinction in the free troposphere

The SAGE 1 and SAM 2 satellite sensors were designed to measure, with global coverage, the 1 micron extinction produced by the stratospheric aerosol. In the absence of high altitude cloud, similar measurements may be made for the free tropospheric aerosol. Median extinction values in the Northern Hemisphere, for altitudes between 5 and 10 km, are found to be one-half to one order of magnitude greater than values at corresponding latitudes in the Southern Hemisphere. In addition, a seasonal increase by a factor of 1.5 yields 2 is observed in both hemispheres in local spring and summer. Following major volcanic eruptions, a long-lived enhancement of the aerosol extinction is observed for altitudes above 5 km

Development of a global model for atmospheric backscatter at CO2 wavelengths

The variation of the aerosol backscattering at 10.6 micrometers within the free troposphere was investigated and a model to describe this variation was developed. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets used were obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series, and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained that describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season