arXiv subjects

Alok Pokharel

Publications and source records attributed to Alok Pokharel.

3 recordsLinked to original sources

arXiv2026

Defect-Width-Tunable Resonant Elastic-Wave Transmission in Micro-Pillar Arrays

Periodic micro-pillar lattices integrated on elastic substrates provide a promising plat-form for controlling elastic-wave propagation through localized resonant interactions. In this work, defect-engineered resonant transmission in periodic tungsten micro-pillar arrays deposited on silicon substrates is numerically investigated using finite-element simulations. Two-dimensional frequency-domain analyses were performed to evaluate the influence of one-, two- and three-pillar defects on elastic wave transmission characteristics. The results reveal strong defect-width-dependent transmission modulation together with the localized resonant elastic-wave redistribution within the periodic lattice. Full three-dimensional simulations further confirm the presence of defect-sensitive resonant localization and modified elastic-wave transport pathways. Floquet dispersion analysis of a periodic unit cell reveals multiple nearly flat resonant branches associated with low-group-velocity elastic-wave modes, indicating predominantly subwavelength locally resonant behavior. A comparative study between tungsten and copper resonators demonstrates enhanced resonant confinement in tung-sten-based structures due to their larger inertial contrast with the supporting sub-strate. The proposed defect-engineered micro-pillar lattices provide an effective approach for frequency-selective elastic-wave control and localized resonant wave ma-nipulation in elastic metamaterial systems.

physics.app-ph↗

arXiv2022

Capacitively coupled distinct mechanical resonators for room temperature phonon-cavity electromechanics

Coupled electromechanical resonators that can be independently driven/detected and easily integrated with external circuits are essential for exploring mechanical modes based signal processing. Here, we present a room temperature phonon-cavity electromechanical system, consisting of two distinct resonators: a silicon nitride electromechanical drum capacitively coupled to an aluminum one. We demonstrate electromechanically induced transparency and amplification in a two-tone driving scheme and observe the phonon-cavity force affecting the mechanical damping rates of both movable objects. We also develop an analytical model based on linearly coupled motion equations, which captures the optomechanical features in the classical limit and enables to fit quantitatively our measurements. Our results open up new possibilities in the study of phonon-cavity based signal processing in the classical and potentially in the future in the quantum regimes.

cond-mat.mes-hall↗

arXiv2021

High-Q silicon nitride drum resonators strongly coupled to gates

Silicon nitride (SiN) mechanical resonators with high quality mechanical properties are attractive for fundamental research and applications. However, it is challenging to maintain these mechanical properties while achieving strong coupling to an electrical circuit for efficient on-chip integration. Here, we present a SiN drum resonator covered with an aluminum thin film, enabling large capacitive coupling to a suspended top-gate. Implementing the full electrical measurement scheme, we demonstrate a high quality factor ~ 1E4 (comparable to that of bare drums at room temperature) and present our ability to detect ? 10 mechanical modes at low temperature. The drum resonator is also coupled to a microwave cavity, so that we can perform optomechanical sideband pumping with a fairly good coupling strength G and demonstrate mechanical parametric amplification. This SiN drum resonator design provides efficient electrical integration and exhibits promising features for exploring mode coupling and signal processing.

physics.app-ph↗