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Optical resonators are indispensable tools in optical metrology that usually benefit from an evacuated and highly-isolated environment to achieve peak performance. Even in the more sophisticated design of Fabry-Perot (FP) cavities, the material choice limits the achievable quality factors. For this reason, monolithic resonators are emerging as promising alternative to traditional designs, but their design is still at preliminary stage and far from being optimized. Here, we demonstrate a monolithic FP resonator with 4.5 cm3 volume and 2 × 105 finesse. In the ambient environment, we achieve 18 Hz integrated laser linewidth and 7 × 10−14 frequency stability measured from 0.08 s to 0.3 s averaging time, the highest spectral purity and stability demonstrated to date in the context of monolithic reference resonators. By locking two separate lasers to distinct modes of the same resonator, a 96 GHz microwave signals is generated with phase noise -100 dBc/Hz at 10 kHz frequency offset, achieving orders of magnitude improvement in the approach of photonic heterodyne synthesis. The compact monolithic FP resonator is promising for applications in spectrally-pure, high-frequency microwave photonic references as well as optical clocks and other metrological devices. ©2024. All rights reserved. Optical resonators are essential tools for high precision metrology and applications where the spectral purity is highly demanded. Here, the authors demonstrate a monolithic resonator made of fused silica to support 18 Hz integrated laser linewidth in the ambient environment, and W-band microwave generation with low phase noise of -100 dBc/Hz at 10 kHz frequency offset. [ABSTRACT FROM AUTHOR]

Optical frequency combs generated by parametric modulation of optical microresonators are usually described by lumped-parameter models, which do not account for the spatial distribution of the modulation. This study highlights the importance of this spatial distribution in the Surface Nanoscale Axial Photonics (SNAP) platform, specifically for elongated SNAP bottle microresonators with a shallow nanometre-scale effective radius variation along its axial length. SNAP bottle microresonators have much smaller free spectral range and may have no dispersion compared to microresonators with other shapes (e.g., spherical and toroidal), making them ideal for generating optical frequency combs with lower repetition rates. By modulating parabolic SNAP bottle microresonators resonantly and adiabatically, we show that the flatness and bandwidth of the optical frequency comb spectra can be enhanced by optimizing the spatial distribution of the parametric modulation. The optimal spatial distribution can be achieved experimentally using piezoelectric, radiation pressure, and electro-optical excitation of a SNAP bottle microresonator. "Previous studies investigating the creation of optical frequency combs through parametric modulation of microresonators rely on lumped-element models that do not consider how the modulations are spatially distributed. The current study underscores the crucial role of these spatial distributions in SNAP bottle microresonators, particularly in producing optical frequency combs with low repetition rate. [ABSTRACT FROM AUTHOR]

Time crystals represent temporal analogues of the spatial self-ordering exhibited by atomic or molecular building blocks of solid-state crystals. The pursuit of discrete time crystals (DTCs) in periodically forced Floquet closed systems has revealed how they can evade thermalization and loss of temporal order. Recently, it has been shown that even with coupling to the ambient and its concomitant noise, some states maintain their time crystalline order, forming dissipative DTCs. Here, we introduce a scheme for the realization and state control of dissipative DTCs hinging on pumping a Kerr optical resonator with a phase-modulated continuous-wave laser. We show the possible symmetry breaking states possess temporal long-range order and analyze the phase noise of the accompanying signature radio frequency (RF) subharmonic. Besides offering a technique for generating high-spectral-purity RF signals, this versatile platform empowers controlled switching between various DTC states through accessible experimental knobs, hence facilitating the future study of DTC phase transitions. Discrete time crystals are a new state of matter emerging via spontaneous discrete translational symmetry breaking in time. The authors demonstrate that a dissipative discrete time crystal appears in an optical microcavity pumped by a phase-modulated continuous wave laser, offering a new route to study this exotic crystal phase. [ABSTRACT FROM AUTHOR]