Search

The measurement and control of mechanical resonators are critical for cavity magnomechanics, which has emerged as an important frontier for hybrid quantum systems based on magnonics. Traditional microwave-based measurements require handling high-frequency signals and cannot achieve field distribution detection. Here, we demonstrate a method for optically measuring and manipulating a ferromagnetic mechanical resonator. This technique allows for direct observation of the response and field distribution of mechanical oscillations during magnomechanically induced transparency/absorption processes, confirming that the mechanical mode S 1 , 2 is coupled with the magnon. The optical measurement not only serves to validate the magnomechanical coupling theory but also reduces the necessity for high-frequency measurements. Furthermore, we utilize the instantaneously measured results to implement feedback control of the self-oscillating mechanical resonator to overcome the dynamical back-action limit, achieving a threefold enhancement of phonon lasing amplitude. This feedback control lays the foundation for the study of quantum cavity magnomechanics, such as the feedback cooling of a magnomechanical resonator. [ABSTRACT FROM AUTHOR]

Generated in high‐Q optical microresonators, dissipative Kerr soliton microcombs constitute broadband optical frequency combs with chip sizes and repetition rates in the microwave to millimeter‐wave range. For frequency metrology applications such as spectroscopy, optical atomic clocks, and frequency synthesizers, octave‐spanning soliton microcombs generated in dispersion‐optimized microresonators are required, which allow self‐referencing for full frequency stabilization. In addition, field‐deployable applications require the generation of such soliton microcombs to be simple, deterministic, and reproducible. Here, a novel scheme to generate self‐emerging solitons in integrated lithium‐niobate microresonators is demonstrated. The single soliton features a broadband spectral bandwidth with dual dispersive waves, allowing 2f–3f self‐referencing. Via harnessing the photorefractive effect of lithium niobate to significantly extend the soliton existence range, a spontaneous yet deterministic single‐soliton formation is observed. The soliton is immune to external perturbation and can operate continuously for over 13 h without active feedback control. Finally, via integration with a pre‐programmed distributed feedback (DFB) laser, turnkey soliton generation is demonstrated. With further improvement of microresonator Q and hybrid integration with chip‐scale laser chips, compact soliton microcomb devices with electronic actuation can be created, which can become central elements for future LiDAR, microwave photonics, and optical telecommunications. [ABSTRACT FROM AUTHOR]

In a traveling wave microresonator, the cascaded four‐wave mixing (FWM) between optical modes allows the generation of frequency combs, including intriguing dissipative Kerr solitons (DKS). This study explores the quantum fluctuations of frequency combs and reveal the continuous‐variable quantum entanglement between different comb lines of the DKS states. The entanglement of DKS exhibits two distinct characteristics. For modes located at the spectral edge with a small number of excitations, different comb modes with multiple colors become entangled due to photon‐pair generation and coherent photon conversion stimulated by the FWM. Notably, a sudden disappearance of quantum entanglement in the center of the DKS spectrum is observed, which is attributed to the self‐locking phenomena in the FWM network. These findings demonstrate the prominent quantum nature of DKS, which is of fundamental significance in quantum optics and has the potential to be utilized in quantum networking and distributed quantum sensing applications. [ABSTRACT FROM AUTHOR]

Synchronization and frequency locking between different oscillators are of scientific and technological importance in a wide variety of fields. The optomechanical resonator can be a good integrated oscillator, which takes place via the radiation pressure force induced by the optical fields. In addition, the breathing soliton is a particular kind of dissipative Kerr soliton that exists between the modulation instability state and the stable state, which shows periodic oscillation in pulse width and amplitude, as well as in its spectral envelope. The breathing frequency depends on the pump power and the pump detuning, which can be affected by environmental fluctuations, and the linewidth of the RF beatnote is on the order of megahertz (MHz). Here, the synchronization of these two different oscillators, that is, the optomechanical oscillator and the breathing soliton, is demonstrated. This demonstration transfers the stability and narrow linewidth of the optomechanical oscillator to the breathing soliton. The fixed phase relation between the breathing oscillation and optomechanical oscillation can be established, forming an open Lissajous diagram. These results provide a new way for the stabilization and control of the breathing soliton and may inspire the study of the interaction between the optomechanical oscillator and the breathing soliton. [ABSTRACT FROM AUTHOR]

Whispering-gallery modes (WGMs) in a zeolite cylinder have been effectively coupled with a low-loss fiber taper. The fiber transmission spectrum directly shows the WGM distribution, which agrees well with the theoretical prediction based on geometric optics. Due to other scattering and absorbing mechanisms, the measured quality factors of the WGMs are limited to approximately 800. This result shows that the fiber taper provides a powerful tool for coupling WGMs of a zeolite cylinder, and this taper-coupled zeolite can be a potential microcavity system for the cavity quantum electrodynamics and the microlaser. OCIS codes: 230.5750, 230.0230, 230.3990.

Thin-film gallium nitride (GaN) is a promising platform for phononic integrated circuits that hold great potential for scalable information processing processors. Here, an unsuspended traveling phononic resonator based on a high-acoustic-index-contrast mechanism is realized in GaN-on-Sapphire with a frequency up to 5 GHz, which matches the typical superconducting qubit frequency. A sixfold increment in quality factor is found when temperature decreases from room temperature (Q = 5000) to 7 K (Q = 30 000), and thus, a frequency-quality factor product of 1.5 × 10 14 is obtained. Higher quality factors should be available when the fabrication process is further optimized. Our system shows great potential in hybrid quantum devices via the so-called circuit quantum acoustodynamics. [ABSTRACT FROM AUTHOR]

The coherent temporal soliton in optical microresonators has attracted great attention recently. Here, we have fabricated the microrod resonator with Q factor as high as $2\times 10^{8}$ and demonstrated the dissipative Kerr soliton generation in such a microresonator, by utilizing an auxiliary-laser-assisted thermal response control. In addition, we have changed the pump laser and observed the perfect soliton crystals. With the simulation, we found that the perfect soliton crystals are generated based on the avoided mode crossing, which is affected by the pump resonance and pump power. [ABSTRACT FROM AUTHOR]

A high-accuracy unsupervised classification model is developed in a multimode self-interference microring resonator (SIMRR). For the SIMRR, there are many whispering gallery modes (WGMs) present. Each of these resonance modes supported by the SIMRR has a different response to different target parameters, so that the SIMRR-based sensor has the super capability to distinguish between multiple components. In the classification model, principal component analysis (PCA) is firstly used to reduce the dimensionality of this multimode sensing information from the SIMRR-based sensor. When the original higher-dimensional data points are projected onto the lower-dimensional data with only the first few principal components, they can be easily categorized into several different types by using density-based spatial clustering of application with noise (DBSCAN) algorithm. As an example, the unsupervised classification method is numerically validated based on a designed three-gas SIMRR-based sensor. The numerical results prove that the classification model can achieve an ultra high classification accuracy for the designed three-gas sensor with more than 60 dB in signal-to-noise ratio. [ABSTRACT FROM AUTHOR]

A multimode microcavity sensor based on a self-interference microring resonator is demonstrated experimentally. The proposed multimode sensing method is implemented by recording wide band transmission spectra that consist of multiple resonant modes. It is different from previous dissipative sensing scheme, which aims at measuring the transmission depth changes of a single resonant mode in a microcavity. Here, by combining the dissipative sensing mechanism and the machine learning algorithm, the multimode sensing information extracted from a broadband spectrum can be efficiently fused to estimate the target parameter. The multimode sensing method is immune to laser frequency noises and robust against system imperfection, thus our work presents a great step towards practical applications of microcavity sensors outside the research laboratory. The voltage applied across the microheater on the chip was adjusted to bring its influence on transmittance through the thermo-optic effects. As a proof-of-principle experiment, the voltage was detected by the multimode sensing approach. The experimental results demonstrate that the limit of detection of the multimode sensing by the general regression neural network is reduced to 6.7% of that of single-mode sensing within a large measuring range. [ABSTRACT FROM AUTHOR]

Electric current sensors are widely utilized in high-frequency power and electronic circuits which spread over numerous industries. Here, a current sensor based on the high-Q whispering gallery mode optical capillary microresonator filled with Terfenol-D nanoparticles is experimentally demonstrated. The device shows a peak AC current sensitivity of 5.285 μA Hz−1/2 with a corresponding high accuracy of 0.0009%. It possesses a wide detection frequency bandwidth of approximately 12 MHz and exhibits good linearity, enabling for partial discharge signals detection. [ABSTRACT FROM AUTHOR]

A hybrid microcavity based on the liquid-metal-filled silica microbubble is experimentally demonstrated, which supports both plasmonic and optical whispering gallery modes. The high quality (Q)-factor plasmonic mode of liquid metal is demonstrated via controlling the polarization of the probe laser as well as changing the liquids in the microbubble. Additionally, we reveal an unconventional Q-factor enhancement effect in the bottle microresonator. The liquid metal (mercury) could dissolve various metals and solids, meriting the optofluidic type of sensing. Combining the two kinds of high-Q resonances in the hybrid microcavity, we could probe the optical, mechanical, and thermal properties of solvents in liquid metal, providing a unique experimental platform for realizing multi-parameter optical sensing and making the detection and identification of metal and alloy possible. [ABSTRACT FROM AUTHOR]

A category of optical microring resonator, which is analogous to the Möbius strip, is proposed. The "Möbius" microring resonator allows the conversion between modes with different polarizations in the ring, and light must circulate two cycles to be converted back to the original polarization status, which is similar to a Möbius strip. This topology structure of polarization makes the free spectral range half of that which corresponds to the cavity round trip. The eigenmodes of this microring are hybridizations of different polarizations, and the breaking of the rotation invariance of the ring makes the transmission related to the polarization of input light and the relative rotation of the cavity. Our work opens the door towards the photonic devices with nontrivial mode topology and provides another way to engineer photonic structures for fundamental studies. [ABSTRACT FROM AUTHOR]

In this paper, we first experimentally demonstrate deterministic generation and switching of dissipative Kerr solitons (DKSs) in a thermally controlled micro-ring resonator based on high-index doped silica glass platform. In our scheme, an auxiliary laser is introduced to timely balance the intra-cavity heat fluctuation. By decreasing the operation temperature through a thermo-electric cooler, primary-, chaotic-comb and soliton crystal are firstly generated, then increasing the temperature, DKSs switching and single soliton are robustly accessed, which is independent of the tuning speed. During the switching process, varieties of DKSs are identified by tens of the characteristic "soliton-steps". Besides, by simply changing the operation temperature under which the DKSs are formed, the center wavelength of dispersive waves could be tuned in a broadband range. When the micro-ring resonator operating at temperature larger than 63.5 °C, avoided mode-crossing free soliton can be obtained. Our results are favorable for study of on-chip soliton dynamics and practical nonlinear applications. [ABSTRACT FROM AUTHOR]

In this work, the thermal bistability of magnons in yttrium iron garnet microspheres was experimentally characterized. Using high quality factor optical whispering gallery modes in the microsphere, the temperature change caused by the microwave pump is precisely measured by probing the optical resonance wavelength shift. It is found that temperature change also induces the magnonic frequency shift and the frequency shift depends on the crystal axis direction of the material. With some appropriate alignment of the magnetic field and the microsphere, the magnonic frequency shift induced by the thermal bistability from the microwave can be suppressed. Our results show its potential use in future experiments on magnon-based transducers. [ABSTRACT FROM AUTHOR]

The general principles of the unidirectional emission of a high-Q whispering gallery mode (WGM) in deformed circular microcavities are studied and presented in this paper. In the phase space of deformed microcavities, light in the chaotic sea leaks out from the cavity through specific refraction regions, the positions of which are determined by the stable islands and the unstable manifolds. By changing the cavity shape, we can tune the positions of the refraction regions, as well as fixed points, to achieve unidirectional emission with narrow angular divergence. The microcavity with high-Q and unidirectional emission makes high-efficient free-space excitation and collection possible; thus, it can be applied for far-field detection of nanoparticles and low-threshold lasers with collimated emission. [ABSTRACT FROM PUBLISHER]