arXiv subjects

A. K. Naik

Publications and source records attributed to A. K. Naik.

6 recordsLinked to original sources

arXiv2022

Independently reconfigurable internal loss and resonance-shift in an interferometer-embedded optical cavity

Optical cavities find diverse uses in lasers, frequency combs, optomechanics, and optical signal processors. Complete reconfigurability of the resonant frequency as well as the loss enables development of generic field programmable cavities for achieving the desired performance in these applications. Conventional reconfigurable cavities are generally limited to specific material platforms or specific optical tuning methods and require sophisticated fabrication. Furthermore, the tuning of the loss is coupled to the resonance-shift in the cavity. We propose and demonstrate a simple and generic interferometer in a cavity structure that enables quasiperiodic modification of the internal cavity loss and the cavity resonance to reconfigure the Q-factor, transmission characteristics, and group delay of the hybrid cavity, with simple tuning of the optical phase in the interferometer. We also demonstrate methods to decouple the tuning of the loss from the resonance-shift, that enables resonance-locked reconfigurability. This structure also enables resonance-shift to both shorter and longer wavelengths using the same phase-tuning technique, which is challenging to achieve in conventional reconfigurable cavities. These devices can be implemented in any guided-wave platform (on-chip or fiber-optic) with potential applications in programmable photonics and reconfigurable optomechanics.

physics.optics↗

arXiv2022

Tunable nonlinear damping in parametric regime

Nonlinear damping plays a significant role in several area of physics and it is becoming increasingly important to understand its underlying mechanism. However, microscopic origin of nonlinear damping is still a debatable topic. Here, we probe and report nonlinear damping in a highly tunable MoS2 nano mechanical drum resonator using electrical homodyne actuation and detection technique. In our experiment, we achieve 2:1 internal resonance by tuning resonance frequency and observe enhanced non-linear damping. We probe the effect of non-linear damping by characterizing parametric gain. Geometry and tunability of the device allow us to reduce the effect of other prominent Duffing non-linearity to probe the non-linear damping effectively. The enhanced non-linear damping in the vicinity of internal resonance is also observed in direct drive, supporting possible origin of non-linear damping. Our experiment demonstrates, a highly tunable 2D material based nanoresonator offers an excellent platform to study the nonlinear physics and exploit nonlinear damping in parametric regime.

cond-mat.mes-hall↗

arXiv2021

Effect of internal resonance on the dynamics of MoS2 resonator

Nonlinear modal interactions and associated internal resonance phenomena have recently been used to demonstrate improved oscillator performance and enhanced sensing capabilities. Here, we show tunable modal interaction in a MoS2 resonator. We achieve the tunability of coupling between these initially uncoupled modes by using electrostatic gate voltages. This tunable coupling enables us to make the modes commensurate and observe energy exchange between the modes. We attribute the strong energy exchange between the vibrational modes to 2:1 internal resonance. This interaction strongly affects the dynamics of the modal response of such resonators. We observe peak splitting, a signature of energy exchange between the modes even when the modal response is in the linear regime. We model our device to explain the observed effect of excitation, detuning of modal frequencies, and intermodal coupling strength on the resonator dynamics. MoS2 resonators explored in this work are ideal for understanding the rich dynamics offered through the intermodal coupling.

cond-mat.mes-hall↗

arXiv2019

Nanomechanical Spectroscopy of Ultrathin Silicon Nitride Suspended Membranes

Mechanical properties of a nanomechanical resonator have a significant impact on the performance of a resonant Nano-electromechanical system (NEMS) device. Here we study the mechanical properties of suspended membranes fabricated out of low-pressure chemical vapor deposited silicon nitride thin films. Doubly-clamped membranes of silicon nitride with thickness less than 50 nm and length varying from 5 um to 60 um were fabricated. The elastic modulus and stress in the suspended membranes were measured using Atomic Force Microscope (AFM)-based nanomechanical spectroscopy. The elastic modulus of the suspended membranes was found to be significantly higher than those of corresponding thin films on the substrate. A reduction in the net stress after the fabrication of suspended membrane was observed and is explained by estimating the contributions of thermal stress and intrinsic stress. We establish a mathematical model to calculate the normalized elastic modulus of a suspended membrane. Lastly, we study the capillary force-gradient between the SiNx suspended membrane-Si substrate that could collapse the suspended membrane.

physics.app-ph↗

arXiv2018

On-Chip Optical Transduction Scheme for Graphene Nano-Electro-Mechanical Systems in Silicon-Photonic Platform

We present a scheme for on-chip optical transduction of strain and displacement of Graphene-based Nano-Electro-Mechanical Systems (NEMS). A detailed numerical study on the feasibility of three silicon-photonic integrated circuit configurations is presented: Mach-Zehnder Interferometer(MZI), micro-ring resonator and ring-loaded MZI. An index-sensing based technique using a Mach-Zehnder Interferometer loaded with a ring resonator with a moderate Q-factor of 2400 can yield a sensitivity of 28 fm/sqrt(Hz), and 6.5E-6 %/sqrt(Hz) for displacement and strain respectively. Though any phase sensitive integrated photonic device could be used for optical transduction, here we show that optimal sensitivity is achievable by combining resonance with phase sensitivity.

physics.optics↗

arXiv2015

Nonlinear Mode Coupling and Internal Resonances in MoS2 Nanoelectromechanical System

Atomically thin two dimensional (2D) layered materials have emerged as a new class of material for nanoelectromechanical systems (NEMS) due to their extraordinary mechanical properties and ultralow mass density. Among them, graphene has been the material of choice for nanomechanical resonator. However, recent interest in 2D chalcogenide compounds has also spurred research in using materials such as MoS2 for NEMS applications. As the dimensions of devices fabricated using these materials shrink down to atomically thin membrane, strain and nonlinear effects have become important. A clear understanding of nonlinear effects and the ability to manipulate them is essential for next generation sensors. Here we report on all electrical actuation and detection of few layers MoS2 resonator. The ability to electrically detect multiple modes and actuate the modes deep into nonlinear regime enables us to probe the nonlinear coupling between various vibrational modes. The modal coupling in our device is strong enough to detect three distinct internal resonances.

cond-mat.mes-hall↗