Governing equations for 1D opto-mechanical vibrations of elastic cubical micro-resonators

© 2017 Informa UK Limited, trading as Taylor & Francis Group In this paper by employing the Lagrangian method, the effect of the radiation pressure on the coupling between the optical and mechanical modes in an elastic cavity is surveyed. The radiation pressure couldn’t be considered as an external force because the electromagnetic waves are non-separable part of the elastic media. Due to the deformation of elastic media, the electromagnetic waves is modified as a result of the element velocity. To consider the electromagnetic evolution, it is preferred to employ the Lagrangian method instead of the second Newton’s law. Here, using an elastic frame, governing equations on opto-mechanical oscillations in an elastic media are derived. In a specific case, by comparing the results to the other methods, it shown that this method is more accurate because the exchange of electromagnetic waves by regarding the movement of the elastic media due to deform is considered

Electric Field Enhancement Around Gold Tip Optical Antenna

© 2015, Springer Science+Business Media New York. This paper provides a new design of gold tip optical antenna based on a specific geometry, and then the change of enhancement of the electric field of plane wave laser excitation with 400 to 700 nm around of the optical antenna are simulated. Changing the geometry of optical antenna includes creating circular gratings with the periods 200 and 300 nm on the shaft of antenna. With the exerting of laser light to the place of these gratings, the distribution of enhancement of the electric field in a plane perpendicular to the shaft has been acquired. Finally, the optimized value for the maximum enhancement at the period of 293 nm is obtained

Analyzing Physics Majors' Specialization Low Interest Using Social Cognitive Career Theory

As students pursue a bachelor's degree in physics, they may ponder over which area to specialize in, such as theory, computation, or experiment. Often students develop preferences and dislikes, but it's unclear when this preference solidifies during their undergraduate experiences. To get a better understanding, we interviewed eighteen physics majors who were at different stages of their degree regarding their interest in theory, computation, and experimental methods. Out of the eighteen students, we chose to analyze only nine students who rated computation and theory the lowest. Our analysis did not include interest in experiment because the ratings were less negative. We used Social Cognitive Career Theory (SCCT) and Lucidchart to analyze students' responses and create individual graphical representations of the influences for each student. Through this, we uncovered how various factors such as learning experiences, self-efficacy, and outcome expectations influenced their low interest in a particular method. We found that lack of knowledge and experience is often the main reason why self-efficacy was lower. Students' lack of interest is also influenced by negative outcome expectations (e.g, math-intensive and a bad work-life balance) more than other SCCT factors. Our findings could help physics departments and educators identify positive and negative factors that could lead to a more motivating and inclusive physics curriculum.Comment: 4 pages, 2 figures, submitted to the Physics Education Research Conference 202

Electric field enhancement of gold tip optical antenna

Copyright © 2015 Inderscience Enterprises Ltd. This paper shows design of gold tip optical antenna based on the specific geometry. The enhancement changes of the electric field of plane wave laser excitation from 400 to 700 nm surrounding the optical antenna are simulated. Based on direct illumination of antenna apex in TENOM back ground signal is produced and cause efficiency of optical microscopy. In practice, one can change of antenna design and decrease this background signal. Developments of geometry incorporating the period change of circular grating in period 200 nm on the shaft of antenna. In addition, the distribution of enhancement of the electric field in a plane perpendicular to the shaft has been acquired

Particle swarm optimization of broadband field enhancement with a grating-assisted plasmonic taper nanoantenna

This work is dedicated to the improvement of the near-field enhancement beneath the gold and silver tip apex due to plasmons excitation on a sub-wavelength grating engraved on the tip lateral surface. To study conditions of the maximal enhancement we have performed PSO-based optimization of intensity in search space of two parameters for gold and silver tip with different cone angles. Parameters of search space are period of the grating and its position in respect to the apex. The grating-assisted tip is illuminated with the incident light with wavelengths of 400 to 1000 nm in our model. All the simulations of electromagnetic waves scattering on the nanoantenna are based on the finite difference time domain method

Carrier-envelope phase control over pathway interference in strong-field dissociation of H2+_2^+

The dissociation of an H$_2^+$ molecular-ion beam by linearly polarized, carrier-envelope-phase-tagged 5 fs pulses at 4$\times10^{14}$W/cm$^2$ with a central wavelength of 730 nm was studied using a coincidence 3D momentum imaging technique. Carrier-envelope-phase-dependent asymmetries in the emission direction of H$^+$ fragments relative to the laser polarization were observed. These asymmetries are caused by interference of odd and even photon number pathways, where net-zero photon and 1-photon interference predominantly contributes at H$^+$+H kinetic energy releases of 0.2 -- 0.45 eV, and net-2-photon and 1-photon interference contributes at 1.65 -- 1.9 eV. These measurements of the benchmark H$_2^+$ molecule offer the distinct advantage that they can be quantitatively compared with \textit{ab initio} theory to confirm our understanding of strong-field coherent control via the carrier-envelope phase

Improvement of near-field enhancement with a grating-assisted gold tapered nanoantenna

This work is dedicated to the improvement of the near-field enhancement beneath the tip apex due to delocalized plasmons excitation on a sub-wavelength grating engraved on the tip mesoscopic surface. To study conditions of the maximal enhancement we have performed PSO-based optimization of intensity in search space of two parameters. Those parameters are period of the grating and its position in respect to the apex. The grating- patterned tip is illuminated with the incident light with wavelengths of 400 to 1000 nm in our model. All the simulations of electromagnetic waves scattering on the nanoantenna are based on the finite difference time domain method

Improvement of near-field enhancement with a grating-assisted gold tapered nanoantenna

This work is dedicated to the improvement of the near-field enhancement beneath the tip apex due to delocalized plasmons excitation on a sub-wavelength grating engraved on the tip mesoscopic surface. To study conditions of the maximal enhancement we have performed PSO-based optimization of intensity in search space of two parameters. Those parameters are period of the grating and its position in respect to the apex. The grating- patterned tip is illuminated with the incident light with wavelengths of 400 to 1000 nm in our model. All the simulations of electromagnetic waves scattering on the nanoantenna are based on the finite difference time domain method

Note: Position dependence of time signals picked off a microchannel plate detector

Citation: Ablikim, U., Zohrabi, M., Jochim, B., Berry, B., Severt, T., Carnes, K. D., & Ben-Itzhak, I. (2015). Note: Position dependence of time signals picked off a microchannel plate detector. Review of Scientific Instruments, 86(1), 3. doi:10.1063/1.4906327Using an ultrafast laser and a precision mask, we demonstrate that time signals picked off directly from a microchannel plate detector depend on the position of the hit. This causes a time spread of about 280 ps, which can affect the quality of imaging measurements using large detectors. (C) 2015 AIP Publishing LLC