We propose a novel scheme for efficient Raman sub-harmonic generation in a system of inhomogeneously broadened atomic vapor with atoms in a closed three-level Λ-configuration. The key feature underlying Raman sub-harmonics generation is microwave-induced hyperfine coherence between the two lower level metastable states. We show explicitly how the amplitude and phase of the microwave field generate controllable spectral amplitudes of Raman sub-harmonics. Our scheme is viable in currently available atomic vapor cells thereby opening the way for efficient sub-harmonic generation in standard experimental setups.
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http://dx.doi.org/10.1364/OL.40.002229 | DOI Listing |
Ultrasound Med Biol
October 2024
Department of Urology, University of Michigan, Ann Arbor, MI, USA. Electronic address:
Objective: The goal of this study was to evaluate the performance of different commercial ultrasound contrast microbubbles (MBs) when measuring bladder phantom pressure with sub-harmonic-aided pressure estimation (SHAPE) methodology. We hypothesized that SHAPE performance is dependent on MB formulation. This study aimed to advance the SHAPE application for bladder pressure measurements in humans.
View Article and Find Full Text PDFNanomaterials (Basel)
July 2023
Department of Optoelectronics, Center for Physical Sciences and Technology (FTMC), Saulėtekio Ave. 3, LT-10257 Vilnius, Lithuania.
The detailed theoretical study of high-frequency signal gain, when a probe microwave signal is comparable to the AC pump electric field in a semiconductor superlattice, is presented. We identified conditions under which a doped superlattice biased by both DC and AC fields can generate or amplify high-frequency radiation composed of harmonics, half-harmonics, and fractional harmonics. Physical mechanisms behind the effects are discussed.
View Article and Find Full Text PDFLocalization has varied applications in biomedicine, such as wireless capsule endoscopy (WCE), detection of cancerous tissue, drug delivery, robotic surgeries, and brain mapping. Currently, most localization systems are battery-powered and suffer from issues regarding battery leakage and limited battery life, resulting in potential health hazards and inconveniences when using them for continuous health monitoring applications. This article proposes an entirely wireless and battery-less 2D localization system consisting of an integrated circuit (IC) that is wirelessly powered at a distance of 4 cm by a 40.
View Article and Find Full Text PDFUltrason Sonochem
March 2023
Department of Biomedical Engineering, School of Bioinformatics, Chongqing University of Posts and Telecommunications, Chongqing, People's Republic of China. Electronic address:
The resonance behaviors of a few lipid-coated microbubbles acoustically activated in viscoelastic media were comprehensively examined via radius response analysis. The size polydispersity and random spatial distribution of the interacting microbubbles, the rheological properties of the lipid shell and the viscoelasticity of the surrounding medium were considered simultaneously. The obtained radius response curves present a successive occurrence of linear resonances, nonlinear harmonic and sub-harmonic resonances with the acoustic pressure increasing.
View Article and Find Full Text PDFUltrasound Med Biol
May 2023
Department of Biometrical Engineering, Schulich School of Engineering, University of Calgary, Alberta, Canada.
Objective: The opening of the blood-brain barrier (BBB) to allow therapeutic drug passage can be achieved by inducing microbubble cavitation using focused ultrasound (FUS). This approach can be monitored through analysis of the received signal to distinguish between stable cavitation associated with safe BBB opening and inertial cavitation associated with blood vessel damage. In this study, FUS phantom and animal studies were used to evaluate the experimental conditions that generate several cross-consistent metrics having the potential to be combined for the reliable, automatic control of cavitation levels.
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