Photon-phonon Interaction Research Articles

Electron–photon–phonon interactions in Dirac semimetals: Magneto-optical absorption and mobility analysis

We study the magneto-optical properties of Dirac semimetal (DSM) slabs with particular emphasis on Cd3As2 through electron–photon–phonon interactions, focusing on the magneto-optical absorption coefficient (MOAC) and full-width at half maximum (FWHM). Studying the Landau level (LL) energy of DSMs in the (xy) plane and the z-direction revealed a unique deviation from the square root dependence on the magnetic field, distinguishing DSMs from other semiconductors. At high magnetic fields, the electron–hole symmetry in the LL spectrum is broken, indicating a topological phase in DSMs. For undoped DSMs, MOAC is driven by interband transitions, with peaks from one-photon absorption being smaller and positioned to the left of two-photon ones. Increasing the magnetic field increases peak values. FWHM for one- and two-photon processes increases with the magnetic field and follows a T dependence on temperature. In doped DSMs, both intraband and interband transitions occur, with new interband peaks emerging at higher temperatures near the Fermi energy. Increased electron density shifts the peak position slightly toward higher energy. Peaks from optical phonon emission are consistently higher and located to the right of those from optical phonon absorption, indicating a stronger emission process. The FWHM data allow for the estimation of electron mobilities, and using a reasonable broadening parameter, our predicted mobility values agree with experimental results.

Anti-resonant acoustic waveguides enabled tailorable Brillouin scattering on chip

Empowering independent control of optical and acoustic modes and enhancing the photon-phonon interaction, integrated photonics boosts the advancements of on-chip stimulated Brillouin scattering (SBS). However, achieving acoustic waveguides with low loss, tailorability, and easy fabrication remains a challenge. Here, inspired by the optical anti-resonance in hollow-core fibers and acoustic anti-resonance in cylindrical waveguides, we propose suspended anti-resonant acoustic waveguides (SARAWs) with superior confinement and high selectivity of acoustic modes, supporting both forward and backward SBS on chip. Furthermore, this structure streamlines the design and fabrication processes. Leveraging the advantages of SARAWs, we showcase a series of breakthroughs for SBS within a compact footprint on the silicon-on-insulator platform. For forward SBS, a centimeter-scale SARAW supports a large net gain exceeding 6.4 dB. For backward SBS, we observe an unprecedented Brillouin frequency shift of 27.6 GHz and a mechanical quality factor of up to 1960 in silicon waveguides. This paradigm of acoustic waveguide propels SBS into a new era, unlocking new opportunities in the fields of optomechanics, phononic circuits, and hybrid quantum systems.

From Phonons to Dark Photons. The Role of Quantum Vacuum BEC in Dark Matter Research

Exploring the quantum vacuum as a dynamic Bose-Einstein Condensate (BEC), this study draws a parallel between phonons and photons to reveal how dark photons can be transformed into visible light. Through phonon-photon interactions, akin to sonoluminescence, we demonstrate the quantum vacuum's ability to illuminate dark matter phenomena. By adapting Einstein's Field Equations, we present a model showcasing spacetime's responsiveness to both visible and dark matter. The process of quantum vacuum cavitation underscores phonons' crucial role in bridging dark and visible realms, providing novel insights into the universe's dark sector.

Photo-thermo-optical modulation of Raman scattering from Mie-resonant silicon nanostructures

Abstract Raman scattering is sensitive to local temperature and thus offers a convenient tool for non-contact and non-destructive optical thermometry at the nanoscale. In turn, all-dielectric nanostructures, such as silicon particles, exhibit strongly enhanced photothermal heating due to Mie resonances, which leads to the strong modulation of elastic Rayleigh scattering intensity through subsequent thermo-optical effects. However, the influence of the complex photo-thermo-optical effect on inelastic Raman scattering has yet to be explored for resonant dielectric nanostructures. In this work, we experimentally demonstrate that the strong photo-thermo-optical interaction results in the nonlinear dependence of the Raman scattering signal intensity from a crystalline silicon nanoparticle via the thermal reconfiguration of the resonant response. Our results reveal a crucial role of the Mie resonance spectral sensitivity to temperature, which modifies not only the conversion of the incident light into heat but also Raman scattering efficiency. The developed comprehensive model provides the mechanism for thermal modulation of Raman scattering, shedding light on the photon–phonon interaction physics of resonant material, which is essential for the validation of Raman nanothermometry in resonant silicon structures under a strong laser field.

Enhanced Photon-Phonon Interaction in WSe2 Acoustic Nanocavities.

Acoustic nanocavities (ANCs) with resonance frequencies much above 1 GHz are prospective to be exploited in sensors and quantum operating devices. Nowadays, acoustic nanocavities fabricated from van der Waals (vdW) nanolayers allow them to exhibit resonance frequencies of the breathing acoustic mode up to f ∼ 1 THz and quality factors up to Q ∼ 103. For such high acoustic frequencies, electrical methods fail, and optical techniques are used for the generation and detection of coherent phonons. Here, we study experimentally acoustic nanocavities fabricated from WSe2 layers with thicknesses from 8 up to 130 nm deposited onto silica colloidal crystals. The substrate provides a strong mechanical support for the layers while keeping their acoustic properties the same as in membranes. We concentrate on experimental and theoretical studies of the amplitude of the optically measured acoustic signal from the breathing mode, which is the most important characteristic for acousto-optical devices. We probe the acoustic signal optically with a single wavelength in the vicinity of the exciton resonance and measure the relative changes in the reflectivity induced by coherent phonons up to 3 × 10-4 for f ∼ 100 GHz. We reveal the enhancement of photon-phonon interaction for a wide range of acoustic frequencies and show high sensitivity of the signal amplitude to the photoelastic constants governed by the deformation potential and dielectric function for photon energies near the exciton resonance. We also reveal a resonance in the photoelastic response (we call it photoelastic resonance) in the nanolayers with thickness close to the Bragg condition. The estimates show the capability of acoustic nanocavities with an exciton resonance for operations with high-frequency single phonons at an elevated temperature.

Ultrafast acousto-optic modulation at the near-infrared spectral range by interlayer vibrations

Abstract The acousto-optic modulation over a broad near-infrared (NIR) spectrum with high speed, excellent integrability, and relatively simple scheme is crucial for the application of next-generation opto-electronic and photonic devices. This study aims to experimentally demonstrate ultrafast acousto-optic phenomena in the broad NIR spectral range of 0.77–1.1 eV (1130–1610 nm). Hundreds of GHz of light modulation are revealed in an all-optical configuration by combining ultrafast optical spectroscopy and light–sound conversion in 10–20 nm-thick bismuth selenide (Bi2Se3) van der Waals thin films. The modified optical transition energy and the line shape in the NIR band indicate phonon–photon interactions, resulting in a modulation of optical characteristics by the photoexcited interlayer vibrations in Bi2Se3. This all-optical, ultrafast acousto-optic modulation approach may open avenues for next-generation nanophotonic applications, including optical communications and processing, due to the synergistic combination of large-area capability, high photo-responsivity, and frequency tunability in the NIR spectral range.

Thermal transport and optical anisotropy in CVD grown large area few-layer MoS2 over an FTO substrate

Atomically thin MoS2 is a promising candidate for its integration into devices due to its strikingly unique electronic, optical, and thermal properties. Here, we report the fabrication of a few-layer MoS2 thin film over a conducting fluorine-doped tin oxide-coated glass substrate via a one-step chemical vapor deposition method. We have quantitatively analyzed the nonlinear temperature-dependent Raman shift using a physical model that includes thermal expansion and three- and four-phonon anharmonic effects, which exhibits that the main origin of nonlinearity in both the phonon modes primarily arises from the three-phonon anharmonic process. We have also measured the interfacial thermal conductance (g) and thermal conductivity (ks) of the synthesized film using the optothermal Raman spectroscopy technique. The obtained values of g and ks are ∼7.218 ± 0.023 MW m−2 K−1 and ∼40 ± 2 W m−1 K−1, respectively, suggesting the suitability of thermal dissipation in MoS2 based electronic and optoelectronic devices. Furthermore, we performed a polarization study using the angle resolved polarized Raman spectroscopy technique under non-resonance and resonance excitations to reveal the electron–photon–phonon interaction in the prepared MoS2, based on the semi-classical theory that includes deformation potential and Fröhlich interaction. Our study provides much needed experimental information about thermal conductivity and polarization response in a few-layer MoS2 grown over the conducting substrate, which is relevant for applications in low power thermoelectric and optoelectronic devices.

Transient measurement of near-field thermal radiation between macroscopic objects.

The involvement of evanescent waves in the near-field regime could greatly enhance spontaneous thermal radiation, offering a unique opportunity to study nanoscale photon-phonon interaction. However, accurately characterizing this subtle phenomenon is very challenging. This paper proposes a transient all-optical method for rapidly characterizing near-field radiative heat transfer (NFRHT) between macroscopic objects, using the first law of thermodynamics. Significantly, a full measurement at a fixed gap distance is completed within tens of seconds. By simplifying the configuration, the transient all-optical method achieves high measurement accuracy and reliable reproducibility. The proposed method can effectively analyze the NFRHT in various material systems, including SiO2, SiC, and Si, which involve different phonon or plasmon polaritons. Experimental observations demonstrate significant super-Planckian radiation, which arises from the near-field coupling of bounded surface modes. Furthermore, the method achieves excellent agreement with theory, with a minimal discrepancy of less than 2.7% across a wide temperature range. This wireless method could accurately characterize the NFRHT for objects with different sizes or optical properties, enabling the exploration of both fundamental interests and practical applications.

Surface acoustic wave confinement inside uncorrelated distributions of subwavelength scatterers

We report an experimental study of surface acoustic wave (SAW) localization and propagation in random metasurfaces composed of Al scatters using pump–probe spectroscopy. Thanks to this technique, wideband high frequency acoustic modes are generated, and their dynamical propagation directly from inside of the media with a high (micrometric) spatial resolution is enabled. During SAW propagation, part of the acoustic wavefront energy is trapped within free areas between the scatterers, acting as cavities. The spectral content of the localized modes of a few GHz is found to depend on the shape and size of the cavities but also on the landscape seen by the wave during its propagation before arriving inside them. The experimental results are supported by numerical simulations using the finite element method. This study is the phononic part of a more global research on the co-localization of elastic and optical waves on random metasurfaces, with the main objective of enhancing the photon–phonon interaction. Applications could range from the design of acousto-optic modulators to ultrasensitive sensors.

Quantum field heat engine powered by phonon-photon interactions

Quantum field heat engine powered by phonon-photon interactions

Photon-phonon quantum cloning in optomechanical system

Quantum cloning is an essential operation in quantum information and quantum computing. Similar to the ‘copy’ operation in classical computing, the cloning of flying bits for further processing from the solid-state quantum bits in storage is an operation frequently used in quantum information processing. Here we propose a high-fidelity and controllable quantum cloning scheme between solid bits and flying bits. In order to overcome the obstacles from the no-cloning theorem and the weak phonon-photon interaction, we introduce a hybrid optomechanical system that performs both the probabilistic cloning and deterministic cloning closed to the theoretical optimal limit with the help of designed driving pulse in the presence of dissipation. In addition, our scheme allows a highly tunable switching between two cloning methods, namely the probabilistic and deterministic cloning, by simply changing the input laser pulse. This provides a promising platform for experimental executability.

Revealing the buildup of dynamic mode-switchable frequency-shifted feedback laser based on photon–phonon interaction

Photon-phonon interaction (PPI) is an intriguing physical phenomenon in which the dynamic photon-phonon energy transfer allows the manipulation of acousto-optic properties in the media. Recently, there has been significant interest of PPI as it accompanies the conservations of energy and momentum processes. Mode-locking is a process in which temporal and spatial resonant modes establish stable synchronization through non-linear interactions. Here, we propose and reveal the buildup of a dynamic mode-switchable frequency-shifted feedback laser in which frequency shift and mode conversion are achieved based on PPI. Moreover, dynamic switching between LP11a/b mode and stable donut mode output is achieved and precisely controlled by PPI. Finally, by using the time-stretch dispersive Fourier transform (TS-DFT) detective system, we observe the transient dynamics established in frequency-shifted feedback (FSF) fiber laser, such as the direct evolution from continuous wave (CW) state to mode-locked state, CW state to multipulse state and subsequently to stable mode-locked state. All these findings would unveil the buildup of mode-locking mechanisms of dynamic mode-switchable FSF fiber lasers based on PPI with more degrees of freedom and unlock new possibilities in ultrafast laser-based technology, optical communication and light control.

Heterogeneous optomechanical crystal cavity coupled by a wavelength-scale mechanical waveguide

Integrated optomechanical crystal (OMC) cavities provide a vital device prototype for highly efficient microwave to optical conversion in quantum information processing. In this work, we propose a novel heterogeneous OMC cavity consisting of a thin-film lithium niobate (TFLN) slab and chalcogenide (ChG) photonic crystal nanobeam coupled by a wavelength-scale mechanical waveguide. The optomechanical coupling rate of the heterogeneous OMC cavity is optimized up to 340 kHz at 1.1197 GHz. Combined with phononic band and power decomposition, 17.38% energy from the loaded RF power is converted into dominant fundamental horizontal shear mode (SH0) in the narrow LN mechanical waveguide. Based on this fraction, as a result, 3.51% power relative to the loaded RF energy is scattered into the fundamental longitudinal mode (L0) facing the TFLN-ChG heterogeneous waveguide. The acoustic breathing mode of the heterogeneous OMC is successfully excited under the driving of the propagating L0 mode in the heterogeneous waveguide, demonstrating the great potentials of the heterogeneous piezo-optomechanical transducer in high-performance photon–phonon interaction fields.

Efficient ultrafast photoacoustic transduction on Tantalum thin films

Nano-acoustic strain generation in thin metallic films via ultrafast laser excitation is widely used in material science, imaging and medical applications. Recently, it was shown that transition metals, such as titanium, exhibit enhanced photoacoustic transduction properties compared to noble metals, such as silver. This work presents experimental results and simulations that demonstrate that among transition metals tantalum exhibits superior photoacoustic properties. Experiments of nano-acoustic strain generation by femtosecond laser pulses focused on thin tantalum films deposited on Silicon substrates are presented. The nano-acoustic strains are measured via pump-probe transient reflectivity that captures the Brillouin oscillations produced by photon–phonon interactions. The observed Brillouin oscillations are correlated to the photoacoustic transduction efficiency of the tantalum thin film and compared to the performance of titanium thin films, clearly demonstrating the superior photoacoustic transduction efficiency of tantalum. The findings are supported by computational results on the laser-induced strains and their propagation in these thin metal film/substrate systems using a two-temperature model in combination with thermo-mechanical finite element analysis. Finally, the role of the metal transducer-substrate acoustic impedance matching is discussed and the possibility to generate appropriately modulated acoustic pulse trains inside the crystalline substrate structures for the development of crystalline undulators used for γ-ray generation is presented.

Tunable phononic coupling in excitonic quantum emitters.

Engineering the coupling between fundamental quantum excitations is at the heart of quantum science and technologies. An outstanding case is the creation of quantum light sources in which coupling between single photons and phonons can be controlled and harnessed to enable quantum information transduction. Here we report the deterministic creation of quantum emitters featuring highly tunable coupling between excitons and phonons. The quantum emitters are formed in strain-induced quantum dots created in homobilayer WSe2. The colocalization of quantum-confined interlayer excitons and terahertz interlayer breathing-mode phonons, which directly modulates the exciton energy, leads to a uniquely strong phonon coupling to single-photon emission, with a Huang-Rhys factor reaching up to 6.3. The single-photon spectrum of interlayer exciton emission features a single-photon purity >83% and multiple phonon replicas, each heralding the creation of a phonon Fock state in the quantum emitter. Due to the vertical dipole moment of the interlayer exciton, the phonon-photon interaction is electrically tunable to be higher than the exciton and phonon decoherence rate, and hence promises to reach the strong-coupling regime. Our result demonstrates a solid-state quantum excitonic-optomechanical system at the atomic interface of the WSe2 bilayer that emits flying photonic qubits coupled with stationary phonons, which could be exploited for quantum transduction and interconnection.

Topological phoxonic crystals for simultaneously controlling electromagnetic and elastic waves

We propose two-dimensional silicon valley phoxonic crystals (VPxCs) to simultaneously exhibit the topological states for electromagnetic and elastic waves. By rotating the trilobal air holes, the coexistence of topological photon and phonon valley Hall phase transitions is achieved due to the breakdown of mirror symmetry. Utilizing this kind of VPxCs, we construct the topological edge states and simultaneously realize topologically valley transmission for both electromagnetic and elastic waves. The simulated results using finite element method show that the proposed VPxCs have robustness against disturbances for both electromagnetic and elastic waves. The acousto-optic (AO) interaction in a topological waveguide-cavity coupled system based on VPxCs is further studied. Results show that obvious shifts of transmission valley of electromagnetic waves during one period of elastic wave. The proposed VPxCs allow for constructing high-performance platforms to realize highly controllable topological photon-phonon interactions with an ultra-small footprint size.

Photon-echo-like phenomenon induced by a phonon

Photon-phonon interaction is a powerful mechanism for all-optical signal processing, slow (fast) light, microscopy, spectroscopy, microwave photonics, and sensing. Here, we demonstrate a photon-echo-like phenomenon induced by a phonon, whose mechanism is represented by a coherent photon-phonon chain interaction (PPCI) theory referring to the alternating evolution between Stokes scattering and anti-Stokes scattering. An analytical solution, including the impulse response of the coherent PPCI theory, is derived to quantitatively analyze the energy conversion between photon and phonon, showing a damped photoacoustic oscillation. All theoretical analysis, numerical simulation, and experiments confirm that the adjacent order echoes have a phase difference of \ensuremath{\pi}, i.e., phase flip, and the echoes generated by using photon and phonon as the initial excitation sources, respectively, are in inverse phase. As a result, the echoes up to the third-order are theoretically analyzed by the proposed coherent PPCI theory and verified by the experiment. This physical mechanism bodes well for a class of photonics applications in telecommunications, optical metrology, and optical computation.

Collapse of Superradiant Phase and Unstable Macroscopic Vacuum State in An-Optomechanical-Dual-Cavity with a Bose-Einstein Condensate

Based on spin-coherent-state variational method, we mainly study the multiple stable macroscopic quantum states and quantum phase transitions of a Bose-Einstein Condensate in an optomechanical dual-cavity by modulating the dual-cavity interaction and the nonlinear phonon-photon interaction. Especially, the collapse of superradiant phase can be tuned in the existing nonlinear photon-phonon interaction, but the critical quantum phase transition point or boundary hasn’t been influenced. As a result, the system occurs an additional phase transition from the superradiant phase to the inversely atomic populated state. Moreover, when dual-cavity coupling interaction increases to a certain value, a new quantum phase transition from the normal phase to the inversely atomic populated state will appear. Finally, the superradiant phase completely collapses and the normal phase also collapses into an unstable macroscopic vacuum state for a strong dual-cavity coupling interaction.

Photon-Phonon Atomic Coherence Interaction of Nonlinear Signals in Various Phase Transitions Eu3+: BiPO4.

We report photon-phonon atomic coherence (cascade- and nested-dressing) interaction from the various phase transitions of Eu3+: BiPO4 crystal. Such atomic coherence spectral interaction evolves from out-of-phase fluorescence to in-phase spontaneous four-wave mixing (SFWM) by changing the time gate. The dressing dip switch and three dressing dips of SFWM result from the strong photon-phonon destructive cross- and self-interaction for the hexagonal phase, respectively. More phonon dressing results in the destructive interaction, while less phonon dressing results in the constructive interaction of the atomic coherences. The experimental measurements of the photon-phonon interaction agree with the theoretical simulations. Based on our results, we proposed a model for an optical transistor (as an amplifier and switch).

Observation of Photon-Phonon Correlations Via Dissipative Filtering

Cavity-optomechanics enables photon-phonon interaction and correlations by harnessing the radiation-pressure force. Here, we realize a ``cavity-in-a-membrane'' optomechanical architecture which allows detection of the motion of lithographically-defined, ultrathin membranes via an integrated optical cavity. Using a dissipative filtering method, we are able to eliminate the probe light in situ and observe photon-phonon correlations associated with the low-frequency membrane mechanical mode. The developed method is generally applicable for study of low-frequency light scattering processes where conventional frequency-selective filtering is unfeasible.