No Arabic abstract
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.
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.
In this work we present a new mechanism for designing phase-gradient metasurfaces (PGMs) to control an electromagnetic wavefront with high efficiency. Specifically, we design a transmission-type PGM formed by a periodic subwavelength metallic slit array filled with identical dielectrics of different heights. It is found that when Fabry-Perot (FP) resonances occur locally inside the dielectric regions, in addition to the common phenomenon of complete transmission, the transmitted phase differences between two adjacent slits are exactly the same, being a non-zero constant. These local FP resonances ensure total phase shift across a supercell that can fully cover the range of 0 to 2Pi, satisfying the design requirements of PGMs. More studies reveal that due to local FP resonances, there is a one-to-one correspondence between the phase difference and the permittivity of the filled dielectric. A similar approach can be extended to the reflection-type case and other wavefront transformation, creating new opportunities for wave manipulation.
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 the fabrication of ultra-low-loss, all-fiber Fabry-Perot cavities containing a nanofiber section, optimized for cavity quantum electrodynamics. By continuously monitoring the finesse and fiber radius during fabrication of a nanofiber between two fiber Bragg gratings, we are able to precisely evaluate taper transmission as a function of radius. The resulting cavities have an internal round-trip loss of only 0.31% at a nanofiber waist radius of 207 nm, with a total finesse of 1380, and a maximum expected internal cooperativity of $sim$ 1050 for a cesium atom on the nanofiber surface. Our ability to fabricate such high-finesse nanofiber cavities may open the door for the realization of high-fidelity scalable quantum networks.
The dynamical response of an optical Fabry-Perot cavity is investigated experimentally. We observe oscillations in the transmitted and reflected light intensity if the frequency of the incoupled light field is rapidly changed. In addition, the decay of a cavity-stored light field is accelerated if the phase and intensity of the incoupled light are switched in an appropriate way. The theoretical model by M. J. Lawrence em et al, JOSA B 16, 523 (1999) agrees with our observations.