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Register a new userHigh Quality Factor Surface Fabry-Perot Cavity of Acoustic Waves
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Surface acoustic wave (SAW) resonators are critical components in wireless communications and many sensing applications. They have also recently emerged as subject of study in quantum acoustics at the single phonon level. Acoustic loss reduction and mode confinement are key performance factors in SAW resonators. Here we report the design and experimental realization of a high quality factor Fabry-Perot SAW resonators formed in between tapered phononic crystal mirrors patterned on a GaN-on-sapphire material platform . The fabricated SAW resonators are characterized by both electrical network analyzer and optical heterodyne vibrometer. We observed standing Rayleigh wave inside the cavity, with an intrinsic quality factor exceeding 13,000 at ambient conditions.
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While nanoscale color generations have been studied for years, high performance transmission structural colors, simultaneously equipped with large gamut, high resolution, low loss and optical multiplexing abilities, still remain as a hanging issue. Here, beneficial from metasurfaces, we demonstrate a silicon metasurface embedded Fabry-Perot cavity (meta-FP cavity), with polydimethylsiloxanes (PDMS) surrounding media and silver film mirrors. By changing the planar geometries of the embedded nanopillars, the meta-FP cavity provides transmission colors with ultra large gamut of 194% sRGB and ultrahigh resolution of 141111 DPI, along with considerably average transmittance of 43% and more than 300% enhanced angular tolerance. Such high density allows two-dimensional color mixing at diffraction limit scale. The color gamut and the resolution can be flexibly tuned and improved by modifying the silver film thickness and the lattice period. The polarization manipulation ability of the metasurface also enables arbitrary color arrangement between cyan and red for two orthogonal linear polarization states, at deep subwavelength scale. Our proposed cavities can be used in filters, printings, optical storages and many other applications in need of high quality and density colors.
Fiber-based optical microcavities exhibit high quality factor and low mode volume resonances that make them attractive for coupling light to individual atoms or other microscopic systems. Moreover, their low mass should lead to excellent mechanical response up to high frequencies, opening the possibility for high bandwidth stabilization of the cavity length. Here, we demonstrate a locking bandwidth of 44 kHz achieved using a simple, compact design that exploits these properties. Owing to the simplicity of fiber feedthroughs and lack of free-space alignment, this design is inherently compatible with vacuum and cryogenic environments. We measure the transfer function of the feedback circuit (closed-loop) and the cavity mount itself (open-loop), which, combined with simulations of the mechanical response of our device, provide insight into underlying limitations of the design as well as further improvements that can be made.
We demonstrate a fiber-integrated Fabry-Perot cavity formed by attaching a pair of dielectric metasurfaces to the ends of a hollow-core photonic-crystal fiber segment. The metasurfaces consist of perforated membranes designed as photonic-crystal slabs that act as planar mirrors but can potentially allow injection of gases through their holes into the hollow core of the fiber. We have so far observed cavities with finesse of ~11 and Q factors of ~$4.5 times 10^5$, but much higher values should be achievable with improved fabrication procedures. We expect this device to enable development of new fiber lasers, enhanced gas spectroscopy, and studies of fundamental light-matter interactions and nonlinear optics.
A Fabry-Perot cavity polarimeter, installed in 2003 at HERA for the second phase of its operation, is described. The cavity polarimeter was designed to measure the longitudinal polarisation of the HERA electron beam with high precision for each electron bunch spaced with a time interval of 96ns. Within the cavity the laser intensity was routinely enhanced up to a few kW from its original value of 0.7W in a stable and controllable way. By interacting such a high intensity laser beam with the HERA electron beam it is possible to measure its polarisation with a relative statistical precision of 2% per bunch per minute. Detailed systematic studies have also been performed resulting in a systematic uncertainty of 1%.
We show that significant water wave amplification is obtained in a water resonator consisting of two spatially separated patches of small-amplitude sinusoidal corrugations on an otherwise flat seabed. The corrugations reflect the incident waves according to the so-called Bragg reflection mechanism, and the distance between the two sets controls whether the trapped reflected waves experience constructive or destructive interference within the resonator. The resulting amplification or suppression is enhanced with increasing number of ripples, and is most effective for specific resonator lengths and at the Bragg frequency, which is determined by the corrugation period. Our analysis draws on the analogous mechanism that occurs between two partially reflecting mirrors in optics, a phenomenon named after its discoverers Charles Fabry and Alfred Perot.
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