arXiv subjects

Adarsh Ganesan

Publications and source records attributed to Adarsh Ganesan.

31 records · Page 2Linked to original sources

arXiv2024

On the Nonlinear Excitation of Phononic Frequency Combs in Molecules

The mechanical analog of optical frequency combs, phononic frequency combs (PFCs), has recently been demonstrated in mechanical resonators via nonlinear coupling among multiple phonon modes. However, for exciting phononic combs in molecules, the requisite strong nonlinear couplings need not be readily present. To overcome this limitation, this paper introduces an alternative route for the generation of phononic combs in polar molecules. Theoretically, we investigated the radiation and phononic spectra generated from CO molecule possessing relatively large permanent dipole moment with density matrix formalism. By considering rovibronic excitation of the ground-state CO molecule while avoiding the electronic excitation, the contribution of the permanent dipole moment and electric dipole polarizability to the creation of PFCs is demonstrated and distinguished. The finding could motivate the possible extension of combs to molecular systems to offer new avenues in molecular sciences.

cond-mat.mes-hall↗

arXiv2023

Mechanical overtone frequency combs

Mechanical frequency combs are poised to bring the applications and utility of optical frequency combs into the mechanical domain. So far, their main challenge has been strict requirements on drive frequencies and power, which complicate operation. We demonstrate a straightforward mechanism to create a frequency comb consisting of mechanical overtones (integer multiples) of a single eigenfrequency, by monolithically integrating a suspended dielectric membrane with a counter-propagating optical trap. The periodic optical field modulates the dielectrophoretic force on the membrane at the overtones of a membrane's motion. These overtones share a fixed frequency and phase relation, and constitute a mechanical frequency comb. The periodic optical field also creates an optothermal parametric drive that requires no additional power or external frequency reference. This combination of effects results in an easy-to-use mechanical frequency comb platform that requires no precise alignment, no additional feedback or control electronics, and only uses a single, mW continuous wave laser beam. This highlights the overtone frequency comb as the straightforward future for applications in sensing, metrology and quantum acoustics.

physics.optics↗

arXiv2020

Existence Conditions for Phononic Frequency Combs

The mechanical analog of optical frequency combs, phononic frequency combs, has recently been demonstrated in mechanical resonators and has been attributed to coupling between multiple phonon modes. This paper investigates the influence of mode structure on comb generation using a model of two nonlinearly coupled phonon modes. The model predicts that there is only one region within the amplitude-frequency space where combs exist, and this region is a subset of the Arnold tongue that describes a 2:1 autoparametric resonance between the two modes. In addition, the location and shape of the comb region are analytically defined by the resonance frequencies, quality factors, mode coupling strength, and detuning of the driving force frequency from the mechanical resonances, providing clear conditions for comb generation. These results enable comb structure engineering for applications in areas as broad as sensing, communications, and quantum information science.

cond-mat.mes-hall↗

arXiv2018

Tracking the resonant frequency of a micromechanical resonator using phononic frequency combs

Micro and nanomechanical resonators have been extensively researched in recent decades for applications to time and frequency references, as well as highly sensitive sensors. Conventionally, the operation of these resonant sensors is practically implemented using a feedback oscillator to dynamically track variations in the resonant frequency. However, this approach places limitations on the frequency stability of the output response, particularly owing to near-carrier phase noise, potentially limiting measurements over long integration times. Here, in this paper, utilizing the recent experimental demonstration of phononic frequency combs, we demonstrate an alternative resonant tracking approach with the potential to provide significant improvements in near-carrier phase noise and long-term stability. In addition, we also showcase comb dynamics mediated resonant frequency modulation which indirectly points to the possible control of inevitable noise processes including thermomechanical fluctuations. This resonant tracking approach may also have general applicability to a number of other physical oscillators.

physics.app-ph↗

arXiv2018

Phononic High Harmonic Generation

This paper reports experimental evidence for phononic low-order to high-order harmonic conversion leading to high harmonic generation. Phononic high harmonic generation is mediated by a threshold dependent instability of a driven phonon mode. Once the threshold for instability is met, a cascade of harmonic generation processes is triggered. Firstly, the up-conversion of first harmonic phonons into second harmonic phonons is established. Subsequently, the down-conversion of second harmonic phonons into first harmonic phonons and conversion of first and second harmonic phonons into third harmonic phonons occur. On the similar lines, an eventual conversion of third harmonic phonons to high orders is also observed to commence. This physical pathway for phononic low-order to high-order harmonic conversion may find general relevance to other physical systems.

physics.class-ph↗

arXiv2017

Discrete intrinsic localized modes in a microelectromechanical resonator

Intrinsic Localized Modes (ILMs) or Discrete Breathers (DBs) are produced through a non-linear vibration localization phenomenon. While Anderson localization is due to lattice defects, the nonlinearity of lattices provides the basis for ILM excitation. Over the past two decades, these ILMs have been realized in a wide range of physical systems including photonic crystals, nonlinear atomic lattices, anti-ferromagnets, coupled Josephson junction arrays and coupled cantilevers. This paper brings out the feasibility of exciting ILMs in a standalone mechanical resonator. Through piezoelectric driving and optical visualization, various intriguing features of ILMs have been recorded. The ILMs in our system are observed as spectral bushes and their frequencies are much lower than that of the drive frequency. The excitation of ILMs is mediated through large amplitude instability following autoparametric excitation of a sub-harmonic mode. The spatial prevalence of discrete ILM excitations is at antinodes of the sub-harmonic mode. Further, the ILMs have been observed to be time-variant and various events including attraction-repulsion (or splitting-merging) of ILMs and hopping occur during the time evolution of ILMs.

nlin.PS↗

arXiv2017

Excitation of coupled phononic frequency combs via two-mode parametric three-wave mixing

This paper builds on the recent demonstration of three-wave mixing based phononic frequency comb. Here, in this process, an intrinsic coupling between the drive and resonant frequency leads to a frequency comb of spacing corresponding to the separation between drive and resonant frequency. Now, in this paper, we experimentally demonstrate the possibility to further excite multiple frequency combs with the same external drive through its coupling with other identical devices. In addition, we also experimentally identify interesting features associated with such a frequency comb generation process.

physics.app-ph↗

arXiv2017

Towards N-mode parametric electromechanical resonances

The ubiquity of parametric resonance is continually evident in the repeated experimental observations of this phenomenon in multiple physical systems. The elementary case of 2 mode parametric resonance of order 1 involves the excitation of a spectral tone of a parametrically driven mode at a sub-harmonic frequency of the higher directly driven mode. Historically, such examples of parametric resonance have been predominantly researched in a system of micro- and nanoelectromechanical resonators. Here, in this paper, we break this convention by showcasing a collection of experimental signatures in support of the concept of "N-mode parametric resonance" using a number of elementary microelectromechanical devices. Specifically, we present observations of 2, 3, (2+3) and (3+3) mode parametric resonances demonstrating co-existence of different regimes within the same device. In addition, we also present observations of intrinsic "Four-Wave Mixing" of parametric excitations. This paper presents contributions towards the existence proof for such multimode parametric resonances which can also be exploited for engineering benefit within the field of "micro and nanoelectromechanical resonators". The experimental results further point towards the possibility of the ultimate observation of N-mode parametric resonance in such physical system.

physics.class-ph↗

arXiv2017

Frequency transitions in phononic four-wave mixing

This work builds upon the recent demonstration of a phononic four-wave mixing (FWM) pathway mediated by parametric resonance. In such a process, drive tones f_d1 and f_d2 associated with a specific phonon mode interact such that one of the drive tones also parametrically excites a second mode at a sub-harmonic frequency and such interactions result in a frequency comb f_d1/2 +/- n(f_d1-f_d2 ). However, the specific behaviour associated with the case where both drive tones can independently excite the sub-harmonic phonon mode has not been studied or previously described. While it may be possible to expect the merger of two frequency combs f_d1/2 +/- n(f_d1-f_d2 ) and f_d2/2 +/- n(f_d1-f_d2 ), this paper indicates that only one of these mechanisms is selected and also shows an interesting transition linked to this process. Such frequency transitions from f_d1/2 +/- n(f_d1-f_d2 ) to f_d2/2 +/- n(f_d1-f_d2 ) holds potential promise for computing applications.

nlin.PS↗

arXiv2017

Excitation of multiple 2-mode parametric resonances by a single driven mode

We demonstrate autoparametric excitation of two distinct sub-harmonic mechanical modes by the same driven mechanical mode corresponding to different drive frequencies within its resonance dispersion band. This experimental observation is used to motivate a more general physical picture wherein multiple mechanical modes could be excited by the same driven primary mode within the same device as long as the frequency spacing between the sub-harmonic modes is less than half the dispersion bandwidth of the driven primary mode. The excitation of both modes is seen to be threshold-dependent and a parametric back-action is observed impacting on the response of the driven primary mode. Motivated by this experimental observation, modified dynamical equations specifying 2-mode auto-parametric excitation for such systems are presented.

nlin.PS↗

arXiv2016

Anomaly in coupled parametric resonance

We present experimental observations of an anomaly in the coupled response of auto-parametrically excited microelectromechanical beams. When one of the two coupled beams is driven at elevated amplitudes, the excitation of dominant and recessive modes is observed in the driven and non-driven beams respectively. This anomalous nature of auto-parametric excitation has been unexplored by both theory and experiments and falls outside the scope of the conventional description of parametric resonance.

nlin.PS↗

arXiv2016

Phononic four-wave mixing

We present the first experimental observations of phononic four-wave mixing (FWM) in a piezoelectrically actuated free-free beam microstructure. The FWM response is facilitated by the intrinsic coupling between a driven mode and an auto-parametrically excited sub-harmonic mode. Motivated by the experimental results, a dynamical model for FWM has been specified.

cond-mat.mes-hall↗

arXiv2016

Hyperfine phononic frequency comb

Optical frequency combs [1-8] have resulted in significant advances in optical frequency metrology and found wide application to precise physical measurements [1-4, 9] and molecular fingerprinting [8]. A direct analogue of frequency combs in the phononic or acoustic domain has not been reported to date. In this letter, we report the first clear experimental evidence for a phononic frequency comb. In contrast to the Kerr nonlinearity [10] in optical frequency comb formation, the phononic frequency comb is generated through the intrinsic coupling of a driven phonon mode with an auto-parametrically excited sub-harmonic mode [16]. Through systematic experiments at different drive frequencies and amplitudes, we portray the well-connected process of phononic frequency comb formation and define attributes to control the features [17-18] associated with comb formation in such a system. Further, the interplay between these nonlinear resonances and the well-known Duffing phenomenon [12-14] is also observed. The presented pathway for phononic frequency comb formation finds general relevance to other nonlinear systems in both classical and quantum domains.

nlin.PS↗