Optomechanical Devices Research Articles

Glutaraldehyde (GA) crosslinked PVA/GO-Ag polymer nanocomposite for optoelectronic and optomechanical applications

We report on the fabrication of Glutaraldehyde (GA) crosslinked PVA/GO-Ag nanocomposite (PVA/GO-Ag/GA) via in situ thermal reduction. A careful and systematic investigation on PVA, PVA/GO, PVA-Ag, PVA/GO-Ag, and PVA/GO-Ag/GA nanocomposites has been explicitly conducted to exemplify the GA influence on enhancing the PVA/GO-Ag composite's structural, optical, and functional properties. Finite Difference Time Domain (FDTD) simulations validate the experimental results by scrutinizing the compositional, morphological, and positional influence of Ag nanoparticles (NPs) in the polymer matrix in a systematic and comprehensive manner. The optical transmittance of PVA/GO-Ag/GA is enhanced up to 51 % (increased by ∼ 89 %, 21 %, and 42 % of PVA/GO, PVA-Ag, and PVA/GO-Ag, respectively) due to the GA cross-linker. The band gap of PVA/GO-Ag/GA was found to be 5.289 eV, which is the lowest of the composites mentioned above. PVA/GO-Ag/GA exhibits enhanced dc conductivity of 17.3 × 10−9 Sm−1. Above measured values of transmittance, optical band gap, and electrical conductivity demonstrate that the fabricated GA crosslinked PVA/GO-Ag nanocomposite is an excellent candidate in terms of its applicability in multispectral imaging, optoelectronic, and optomechanical devices.

Nanomechanical Crystalline AlN Resonators with High Quality Factors for Quantum Optoelectromechanics.

High-quality factor (Qm) mechanical resonators are crucial for applications where low noise and long coherence time are required, as mirror suspensions, quantum cavity optomechanical devices, or nanomechanical sensors. Tensile strain in the material enables the use of dissipation dilution and strain engineering techniques, which increase the mechanical quality factor. These techniques have been employed for high-Qm mechanical resonators made from amorphous materials and, recently, from crystalline materials such as InGaP, SiC, and Si. A strained crystalline film exhibiting substantial piezoelectricity expands the capability of high-Qm nanomechanical resonators to directly utilize electronic degrees of freedom. In this work, nanomechanical resonators with Qm up to 2.9 × 107 made from tensile-strained 290 nm-thick AlN are realized. AlN is an epitaxially-grown crystalline material offering strong piezoelectricity. Nanomechanical resonators that exploit dissipation dilution and strain engineering to reach a Qm × fm-product approaching 1013 Hz at room temperature are demonstrated. A novel resonator geometry is realized, triangline, whose shape follows the Al-N bonds and offers a central pad patterned with a photonic crystal. This allows to reach an optical reflectivity above 80% for efficient coupling to out-of-plane light. The presented results pave the way for quantum optoelectromechanical devices at room temperature based on tensile-strainedAlN.

Ingot-like class of wavefront sensors for laser guide stars

Context. Full sky coverage adaptive optics (AO) on extremely large telescopes requires the adoption of several laser guide stars as references. With such large apertures, the apparent elongation of the beacons is absolutely significant. With a few exceptions, wavefront sensors (WFSs) designed for natural guide stars can be adapted and used in suboptimal mode in this context. Aims. We analyse and describe the geometrical properties of a class of WFSs that are specifically designed to deal with laser guide stars propagated from a location in the immediate vicinity of the telescope aperture. Methods. We describe, in three dimensions, the loci where the light of the laser guide stars would focus in the focal volume located behind the focal plane where astronomical objects are reimaged. We also describe the properties of several types of optomechanical devices that act as perturbers for this new class of pupil plane sensors, through refraction and reflections. We refer to these as ingot WFSs. Results. We provide the recipes both for the most reasonably complex version of these WFSs, with six pupils and, for the simplest one, only three pupils. Both of them are referred to on the basis of the European Extremely Large Telescope (ELT) case. We outlined elements that are meant to give a qualitative idea of how the sensitivity of this new class of sensors compares to conventional ones. Conclusions. We present a new class of WFSs, based on an extension to the case of elongated sources at a finite distance of the pyramid WFS. We point out which advantages of the pyramid can be retained and how it may be adopted to optimize the sensing procedure.

Design of second-order phoxonic topological insulators with customized bandgaps

Second-order phononic and photonic topological insulators hosting topologically protected edge and corner states provide opportunities for the robust manipulation of elastic/acoustic and electromagnetic (EM) waves, respectively. Despite their potential, the development of second-order phoxonic topological insulators, which combine functionalities of second-order phononic and photonic topological insulators, remains largely unexplored. Herein, we design second-order phoxonic topological insulators (SPTI) with customized bandgaps. An inverse design approach is proposed to engineer phoxonic crystals (PCs) featuring customized odd-order phononic and photonic bandgaps simultaneously. Topological phase transition is induced by translating the primitive unit cell (UC) of the inverse-designed PC with half of the lattice constant horizontally and vertically. Thereafter, the SPTI is constructed by juxtaposing the primitive and translated UCs to form a corner between them. Multiple SPTIs, capable of manipulating both acoustic and EM waves, as well as those governing elastic and EM waves, are created. Our work paves the way for customized SPTIs with tailored bandgaps to support diverse phononic and photonic corner states. Meanwhile, the designed SPTIs also provide a platform to design the higher-order topological optomechanical devices.

Tunable on-chip optical traps for levitating particles based on single-layer metasurface

Abstract Optically levitated multiple nanoparticles have emerged as a platform for studying complex fundamental physics such as non-equilibrium phenomena, quantum entanglement, and light–matter interaction, which could be applied for sensing weak forces and torques with high sensitivity and accuracy. An optical trapping landscape of increased complexity is needed to engineer the interaction between levitated particles beyond the single harmonic trap. However, existing platforms based on spatial light modulators for studying interactions between levitated particles suffered from low efficiency, instability at focal points, the complexity of optical systems, and the scalability for sensing applications. Here, we experimentally demonstrated that a metasurface which forms two diffraction-limited focal points with a high numerical aperture (∼0.9) and high efficiency (31 %) can generate tunable optical potential wells without any intensity fluctuations. A bistable potential and double potential wells were observed in the experiment by varying the focal points’ distance, and two nanoparticles were levitated in double potential wells for hours, which could be used for investigating the levitated particles’ nonlinear dynamics, thermal dynamics and optical binding. This would pave the way for scaling the number of levitated optomechanical devices or realizing paralleled levitated sensors.

Used High Collimation UV-LEDs With a Miniaturized Optomechanical Device for the Detection of Direct Bilirubin

Used High Collimation UV-LEDs With a Miniaturized Optomechanical Device for the Detection of Direct Bilirubin

Sensing directional noise baths in levitated optomechanics

Optomechanical devices are being harnessed as sensors of ultraweak forces for applications ranging from inertial sensing to the search for the elusive dark matter. For the latter, there is a focus on detection of either higher energy single recoils or ultralight, narrow-band sources; a directional signal is expected. However, the possibility of searching for a stochastic stream of weak impulses, or more generally a directional broadband signal, need not be excluded; with this and other applications in mind, we apply Gaussian white noise impulses with a well defined direction Ψ to a levitated nanosphere trapped and 3D cooled in an optical tweezer. We find that cross-correlation power spectra offer a calibration-free distinctive signature of the presence of a directional broadband force and its orientation quadrant, unlike normal power spectral densities (PSDs). We obtain excellent agreement between theoretical and experimental results. With calibration we are able to measure the angle Ψ, akin to a force compass in a plane. We discuss prospects for extending this technique into the quantum regime and compare the expected behavior of quantum baths and classical baths. Published by the American Physical Society 2024

High-Transconductance and Low-Leakage Current Single Aluminum Nitride Nanowire Field Effect Transistor

This study presents electrical transport properties of a catalyst-free grown single aluminum nitride nanowire field effect transistor (AlNNW-FET) exhibiting a very high transconductance of 26.9 pS, high on/off current ratio of 795.9, high conductivity of 9.8 x 10-4 Ω-1.cm-1, and a very low leakage current of 10 pA. The conductivity of AlN nanowire is two orders of magnitude higher than the reported studies. The AlNNW-FET reveals a dominant p-type conductivity. The p-type conductivity can be attributed to aluminum vacancies and complexes composed of Al vacancies and oxygen impurities. In consequence, the fabricated AlNNW-FET with high-performance, cost-effectiveness, and high-power efficiency is very well suited for use in low power and high temperature nanoelectronic and piezoelectric sensor applications, as well as integrated electro-optical devices including optomechanical devices and pyroelectric photodetectors.

Simultaneous guidance of electromagnetic and elastic waves via glide symmetry phoxonic crystal waveguides

A phoxonic crystal waveguide with the glide symmetry is designed, in which both electromagnetic and elastic waves can propagate along the glide plane at the same time. Due to the glide symmetry, the bands of the phoxonic crystal super-cell degenerate in pairs at the boundary of the Brillouin zone. This is the so-called band-sticking effect and it causes the appearance of gapless guided-modes. By adjusting the magnitude of the glide dislocation the edge bandgaps, the bandgap of the guided-modes at the boundary of the Brillouin zone, can be further adjusted. The photonic and phononic guided-modes can then possess only one mode for a certain frequency with relatively low group velocities, achieving single-mode guided-bands with relatively flat dispersion relationship. In addition, there exists acousto–optic interaction in the cavity constructed by the glide plane. The proposed waveguide has potential applications in the design of novel optomechanical devices.

Dissipative optomechanics in high-frequency nanomechanical resonators

The coherent transduction of information between microwave and optical domains is a fundamental building block for future quantum networks. A promising way to bridge these widely different frequencies is using high-frequency nanomechanical resonators interacting with low-loss optical modes. State-of-the-art optomechanical devices rely on purely dispersive interactions that are enhanced by a large photon population in the cavity. Additionally, one could use dissipative optomechanics, where photons can be scattered directly from a waveguide into a resonator hence increasing the degree of control of the acousto-optic interplay. Hitherto, such dissipative optomechanical interaction was only demonstrated at low mechanical frequencies, precluding prominent applications such as the quantum state transfer between photonic and phononic domains. Here, we show the first dissipative optomechanical system operating in the sideband-resolved regime, where the mechanical frequency is larger than the optical linewidth. Exploring this unprecedented regime, we demonstrate the impact of dissipative optomechanical coupling in reshaping both mechanical and optical spectra. Our figures represent a two-order-of-magnitude leap in the mechanical frequency and a tenfold increase in the dissipative optomechanical coupling rate compared to previous works. Further advances could enable the individual addressing of mechanical modes and help mitigate optical nonlinearities and absorption in optomechanical devices.

Active-feedback quantum control of an integrated low-frequency mechanical resonator

Preparing a massive mechanical resonator in a state with quantum limited motional energy provides a promising platform for studying fundamental physics with macroscopic systems and allows to realize a variety of applications, including precise sensing. While several demonstrations of such ground-state cooled systems have been achieved, in particular in sideband-resolved cavity optomechanics, for many systems overcoming the heating from the thermal bath remains a major challenge. In contrast, optomechanical systems in the sideband-unresolved limit are much easier to realize due to the relaxed requirements on their optical properties, and the possibility to use a feedback control schemes to reduce the motional energy. The achievable thermal occupation is ultimately limited by the correlation between the measurement precision and the back-action from the measurement. Here, we demonstrate measurement-based feedback cooling on a fully integrated optomechanical device fabricated using a pick-and-place method, operating in the deep sideband-unresolved limit. With the large optomechanical interaction and a low thermal decoherence rate, we achieve a minimal average phonon occupation of 0.76 when pre-cooled with liquid helium and 3.5 with liquid nitrogen. Significant sideband asymmetry for both bath temperatures verifies the quantum character of the mechanical motion. Our method and device are ideally suited for sensing applications directly operating at the quantum limit, greatly simplifying the operation of an optomechanical system in this regime.

Terahertz phononic crystal in plasmonic nanocavity

Interaction between photons and phonons in cavity optomechanical systems provides a new toolbox for quantum information technologies. A GaAs/AlAs pillar multi-optical mode microcavity optomechanical structure can obtain phonons with ultra-high frequency (~THz). However, the optical field cannot be effectively restricted when the diameter of the GaAs/AlAs pillar microcavity decreases below the diffraction limit of light. Here, we design a system that combines Ag nanocavity with GaAs/AlAs phononic superlattices, where phonons with the frequency of 4.2 THz can be confined in a pillar with ~4 nm diameter. The Q c/V reaches 0.22 nm−3, which is ~80 times that of the photonic crystal (PhC) nanobeam and ~100 times that of the hybrid point-defect PhC bowtie plasmonic nanocavity, where Q c is optical quality factor and V is mode volume. The optomechanical single-photon coupling strength can reach 12 MHz, which is an order of magnitude larger than that of the PhC nanobeam. In addition, the mechanical zero-point fluctuation amplitude is 85 fm and the efficient mass is 0.27 zg, which is much smaller than the PhC nanobeam. The phononic superlattice-Ag nanocavity optomechanical devices hold great potential for applications in the field of integrated quantum optomechanics, quantum information, and terahertz-light transducer.

Photonic transistor based on a coupled-cavity system with polaritons.

We investigate the transmission of probe fields in a coupled-cavity system with polaritons and propose a theoretical schema for realizing a polariton-based photonic transistor. When probe light passes through such a hybrid optomechanical device, its resonant point with Stokes or anti-Stokes scattered effects, intensity with amplification or attenuation effects, as well as group velocity with slow or fast light effects can be effectively controlled by another pump light. This controlling depends on the exciton-photon coupling and single-photon coupling. We also discover an asymmetric Fano resonance in transparency windows under the strong exciton-photon coupling, which is different from general symmetric optomechanically induced transparency. Our results open up exciting possibilities for designing photonic transistors, which may be useful for implementing polariton integrated circuits.

The Development of Optomechanical Sensors—Integrating Diffractive Optical Structures for Enhanced Sensitivity

The term optomechanical sensors describes devices based on coupling the optical and mechanical sensing principles. The presence of a target analyte leads to a mechanical change, which, in turn, determines an alteration in the light propagation. Having higher sensitivity in comparison with the individual technologies upon which they are based, the optomechanical devices are used in biosensing, humidity, temperature, and gases detection. This perspective focuses on a particular class, namely on devices based on diffractive optical structures (DOS). Many configurations have been developed, including cantilever- and MEMS-type devices, fiber Bragg grating sensors, and cavity optomechanical sensing devices. These state-of-the-art sensors operate on the principle of a mechanical transducer coupled with a diffractive element resulting in a variation in the intensity or wavelength of the diffracted light in the presence of the target analyte. Therefore, as DOS can further enhance the sensitivity and selectivity, we present the individual mechanical and optical transducing methods and demonstrate how the DOS introduction can lead to an enhanced sensitivity and selectivity. Their (low-) cost manufacturing and their integration in new sensing platforms with great adaptability across many sensing areas are discussed, being foreseen that their implementation on wider application areas will further increase.

All-Optical, Air-Coupled Ultrasonic Detection of Low-Pressure Gas Leaks and Observation of Jet Tones in the MHz Range

We used an ultrasensitive, broadband optomechanical ultrasound sensor to study the acoustic signals produced by pressurized nitrogen escaping from a variety of small syringes. Harmonically related jet tones extending into the MHz region were observed for a certain range of flow (i.e., Reynolds number), which is in qualitative agreement with historical studies on gas jets emitted from pipes and orifices of much larger dimensions. For higher turbulent flow rates, we observed broadband ultrasonic emission in the ~0–5 MHz range, which was likely limited on the upper end due to attenuation in air. These observations are made possible by the broadband, ultrasensitive response (for air-coupled ultrasound) of our optomechanical devices. Aside from being of theoretical interest, our results could have practical implications for the non-contact monitoring and detection of early-stage leaks in pressured fluid systems.

Integrated Photonic Optomechanical Atomic Force Microscopy Probes Batch Fabricated Using Deep UV Photolithography

Chip-scale planar nanofabricated optomechanical devices that optically couple a mechanical moving nanostructure to an on-chip photonic cavity of high quality factor can be used for sensing motion with high precision and bandwidth. Motion in nanoscale mechanical structures can be measured optically on-chip with unprecedented precision and bandwidth. Wider scientific and commercial adoption of such sensors required the ability to mass fabricate, flexibility of design, and permanent fiber attachment for robustness and ease of use. In this paper, we demonstrated this by fabricating an atomic force microscopy probe using a commercial foundry process employing deep UV photolithography on 200 mm wafers. The batch fabricated devices with 150 nm minimum features perform similarly to the research prototypes previously fabricated using sequential electron beam lithography. This demonstration eliminates a key technical barrier to the wider adoption of high-performance integrated optomechanical sensing in nanomechanical transducers. 2022-0186

High-Q Trampoline Resonators from Strained Crystalline InGaP for Integrated Free-Space Optomechanics.

Nanomechanical resonators realized from tensile-strained materials reach ultralow mechanical dissipation in the kHz to MHz frequency range. Tensile-strained crystalline materials that are compatible with epitaxial growth of heterostructures would thereby at the same time allow realizing monolithic free-space optomechanical devices, which benefit from stability, ultrasmall mode volumes, and scalability. In our work, we demonstrate nanomechanical string and trampoline resonators made from tensile-strained InGaP, which is a crystalline material that is epitaxially grown on an AlGaAs heterostructure. We characterize the mechanical properties of suspended InGaP nanostrings, such as anisotropic stress, yield strength, and intrinsic quality factor. We find that the latter degrades over time. We reach mechanical quality factors surpassing 107 at room temperature with a Q·f product as high as 7 × 1011Hz with trampoline-shaped resonators. The trampoline is patterned with a photonic crystal to engineer its out-of-plane reflectivity, desired for efficient signal transduction of mechanical motion to light.

Strong squeezing and robust entanglement in a second-order coupled optomechanical cavity assisted by a Kerr nonlinear medium

We investigate theoretically an optomechanical system composed of an optical mode and a mechanical mode interacting through first-order coupling and second-order coupling in the presence of a Kerr nonlinear medium. We study how the nonlinearities (second-order optomechanical coupling and Kerr nonlinearity) alter the optical output spectrum, optical quadrature squeezing and optomechanical entanglement. It is shown that the intensity of the output optical spectrum decreases drastically with an increase in second-order optomechanical coupling while it increases significantly with an increase in Kerr nonlinear parameter. More interestingly, by choosing suitable second-order optomechanical coupling and detuning of the optical cavity field, one can achieve strong squeezing of the cavity light field. Further, these nonlinearities play an important role in creating robust optomechanical entanglement between optical and mechanical modes. Hence, the presence of various nonlinearities in the system can be a good platform for achieving the squeezing of light and robust optomechanical entanglement which can be used in realizing better quantum optomechanical devices.

Nonreciprocal slow or fast light in anti- PT -symmetric optomechanics

Non-Hermitian systems with anti-parity-time ($\mathcal{APT}$) symmetry have revealed rich physics beyond conventional systems. Here, we study optomechanics in an $\mathcal{APT}$-symmetric spinning resonator and show that, by tuning the rotating speed to approach the exceptional point (EP) or the non-Hermitian spectral degeneracy, nonreciprocal light transmission with a high isolation ratio can be realized. Accompanying this process, nonreciprocal group delay or advance is also identified in the vicinity of EP. Our work sheds new light on manipulating laser propagation with optomechanical EP devices and, in a broader view, can be extended to explore a wide range of $\mathcal{APT}$-symmetric effects, such as $\mathcal{APT}$-symmetric phonon lasers, $\mathcal{APT}$-symmetric topological effects, and $\mathcal{APT}$-symmetric force sensing or accelerator.

Higher-order sideband based on transparent windows in a two-cavity optomechanical system

We present a scheme to realize the regulation of single and double transparent windows in a two-cavity optomechanical device. By studying the output field through the two-cavity device, we not only show the transmission spectrum of the probe field and the second-order sideband process, but also analyze the physical mechanism of the induced transparency window and the efficiency of the second-order sideband process. Moreover, the optomechanically induced transparency window and the coupling of two cavities resulting in transparency window are discussed. We find that the transparency windows and the second-order sideband process can be modulated by the power of the control field and the coupling strength between two cavities. Our device is feasible for controlling light propagation, which might have potential application in quantum optical devices and quantum information networks.