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Normal mode splitting in quantum degenerate Fermi gas in nano-cavity
摘要： We report the normal mode splitting in the fermionic displacement spectrum as a single mode light field interacts with a mechanical mode of ultra-cold quantum degenerate Fermi gas trapped inside a Fabry–Pérot cavity in the strong coupling regime. We explain the normal mode splitting in the outgoing field of the cavity field and in the field quadratures as well. As a function of system parameters, such as coupling strength between fermionic mode and field mode, number of fermionic atoms, cavity decay rate and fluctuations associated with the fermionic mode we explain the phenomenon of normal mode splitting. The low-lying fermions ensemble displays a collective density oscillation associated with particle-hole excitations, which interacts with cavity light field and lead to the observation of NMS in the fermion quadratures and light modes. The numerical results based on the present day laboratory experiments agree with the obtained analytical results.
关键词： Fabry–Pérot cavity,quantum degenerate Fermi gas,Normal mode splitting,fermionic displacement spectrum,strong coupling regime
更新于2025-09-09 09:28:46
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Bimodal Resonance Phenomena—Part III: High-Contrast Grating Reflectors
摘要： The extraordinary broadband high-reflectivity features of high-contrast gratings (HCGs) are stimulating great interest in many optoelectronic applications. In view of obtaining a simple simulation framework, the analogy of HCG reflectors with bimodal Fabry–Pérot interferometers is proposed. The closed-form expressions of the interferometer reflectivity, obtained starting from a novel parametrization of the scattering matrices characterizing the bar–air interface, allow a complete exploration of the device parameter space, explaining and predicting the phenomenon of ultra-broadband quasi-100% reflectivity. In this paper, an optimized and numerically efficient design procedure is described and compared with the standard rigorous coupled wave analysis, both for the classical bar-in-air configuration and for a more robust and practical one, with bars lying on a dielectric support. It is shown that the model can be applied also in the more realistic case of lossy gratings.
关键词： Gratings,Fabry-Pérot interferometers
更新于2025-09-09 09:28:46
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Metamaterial-Inspired Self Polarizing Dual Band Dual-Orthogonal Circularly Polarized Fabry-Perot Resonator Antennas
摘要： This study presents a Fabry-Perot resonator antenna (FPRA) with dual-band dual-orthogonal circular polarization. The whole FPRA consists of a linearly polarized microstrip patch antenna and a chiral metamaterial superstrate. The linearly polarized microstrip antenna serves as the feed system, while the chiral metamaterial (CMM) superstrate has the function of polarization transformation. The CMM also works as a partial reflective sheet to form an FPRA. Ray-tracing method in the circular base is introduced to describe the mechanism of this type of FPRA. Furthermore, the procedure of controlling the frequency ratio of two bands is discussed as well. An antenna prototype is fabricated to validate the simulated results. In the frequency band from 7.24 GHz to 7.36 GHz, the proposed FPRA produces right-handed circularly polarized wave. However, left-handed circularly polarized wave is achieved when the frequency ranges from7.96 GHz to 8.14 GHz. The realized gains reach 12.98 dBic at 7.28 GHz and 13.25 dBic at 8 GHz, respectively.
关键词： Fabry-Perot resonator antenna,dual-orthogonal circular polarizations,dual-band,chiral metamaterial,high gain,self-polarizing
更新于2025-09-09 09:28:46
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Porous Silicon Bragg Reflector/Carbon Dot Hybrids: Synthesis, Nanostructure, and Optical Properties
摘要： Carbon dots (C-dots) exhibit unique fluorescence properties, mostly depending upon their physical environments. Here we investigate the optical properties and nanostructure of Carbon dots (C-dots) which are synthesized in situ within different porous Silicon (PSi) Bragg reflectors. The resulting hybrids were characterized by photoluminescence, X-ray photoelectron, and Fourier Transform Infrared spectroscopies, as well as by confocal and transmission electron microscopy. We show that by tailoring the location of the PSi Bragg reflector photonic bandgap and its oxidation level, the C-dots emission spectral features can be tuned. Notably, their fluorescence emission can be significantly enhanced when the high reflection band of the PSi host overlaps with the confined C-dots’ peak wavelength, and the PSi matrix is thermally oxidized at mild conditions. These phenomena are observed for multiple compositions of PSi Bragg reflectors/C-dots hybrids.
关键词： optical properties,fluorescence,Fabry–Pérot,Bragg reflectors,porous silicon,photoluminescence,carbon dots
更新于2025-09-09 09:28:46
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Parametric resonances in a temporal photonic crystal slab
摘要： We have studied resonances in a dynamic slab whose permittivity and/or permeability are periodic functions of time, namely, a temporal photonic crystal. We find strong and narrow resonances for frequencies that are equal to 1/2 or 3/2, etc. of the modulation frequency provided that a certain geometric parameter (proportional to the slab thickness and to the modulation frequency) assumes values such that the electric field in the slab is either symmetric or antisymmetric with respect to the slab center. These resonances turn out to be absent whenever the electric and magnetic modulations are in phase and have equal strengths, that is, when there are no band gaps between k bands. The resonance peaks appear for all the modulation harmonics and are superimposed on Fabry-Pérot–like background oscillations. For not very strong modulations, the resonances can be described in terms of the relative impedance of the slab and a parameter that expresses the modulation strength.
关键词： modulation frequency,dynamic slab,Fabry-Pérot–like oscillations,parametric resonances,permittivity,temporal photonic crystal,permeability
更新于2025-09-09 09:28:46
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Fiber-optic Fabry-Perot sensor for simultaneous measurement of tilt angle and vibration acceleration
摘要： A fiber-optic Fabry-Perot (F-P) sensor, based on a pendulum structure, for simultaneous measurement of tilt angle and vibration acceleration was proposed, which also has a high tilt angle resolution. The real-time cavity lengths are absolutely measured using a fast demodulation algorithm. The tilt angle is estimated from the mean value of the real-time cavity lengths while the vibration acceleration derives from the alternating quantity of them. A series of experiments are conducted using a micro-tilt platform and a vibration table to simulate tilt angle change and the vibration perturbation, respectively. The experimental results show a tilt angle resolution of 0.023″ in the measurement range from -2.8° to 2.6°. Meanwhile, the vibration acceleration results are obtained by using a spectral analysis to the alternating quantity and basing on a non-linear fitting curve of the frequency response of the acceleration sensibility, within the frequency range of 0~180 Hz.
关键词： vibration acceleration,simultaneous measurement,tilt angle,pendulum,Fabry-Perot interferometer
更新于2025-09-09 09:28:46
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Fabrication and metrology of lithium niobate narrowband optical filters for the solar orbiter
摘要： We report on the fabrication of custom voltage tunable etalons for the SO/PHI spaceborne solar imaging instrument [A. Gandorfer, S. K. Solanki, J. Woch, V. M. Pillet, A. A. Herrero, and T. Appourchaux, J. Phys.: Conference Series 271, 012086 (2011)]. The etalons were manufactured to place a transmission maximum within 0.3 ? of the FeI emission line at 6175.0 ?. Meeting this specification requires an overall thickness specified to within ±15 nm, over a 60 mm aperture. We describe here the metrology, modelling and coating procedures we developed to achieve this.
关键词： electrooptic,Fabry-Perot,filter,lithium niobate,etalon,solar
更新于2025-09-09 09:28:46
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Bi-layer Metamaterial based Broadband Linear Polarization Converter under Two Coherent Beam Illumination
摘要： We demonstrate a bi-layer metamaterial structure with mirror symmetry that acts as a linear polarization converter under two-antisymmetric-beam illumination. Its high performance, including broad bandwidth, high transmittance and high efficiency, originates from the combination of two interference processes: the Fabry-Pérot-like cavity effect between two metallic patterned layers and coherent excitations of spatially separated subwavelength resonators. Terahertz (THz) experiments show good agreement with numerical simulations.
关键词： Fabry-Pérot-like cavity,broadband,THz experiments,linear polarization converter,high efficiency,bi-layer metamaterial,coherent excitations,high transmittance
更新于2025-09-09 09:28:46
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Simultaneous Measurement of Air Pressure and Temperature Using Fiber-Optic Cascaded Fabry-Perot Interferometer
摘要： We propose and demonstrate a fiber-optic cascaded-cavity Fabry-Perot interferometer (FPI) for simultaneous measurement of air pressure and temperature. The open-cavity hybrid FPI consists of an air-cavity and a silica-cavity formed by a section of silica tube and photonic crystal fiber (PCF), respectively. The air-cavity and silica-cavity exhibit different sensitivities to air pressure and temperature. Thus, the proposed sensor can be used to implement air pressure and temperature sensing simultaneously. The spectra of the air-cavity and silica-cavity are extracted from the total reflection spectrum with designed band-pass filters. The air pressure and temperature sensitivities of the air-cavity are 4.04 pm/kPa and 0.87 pm/℃, respectively, and those of the silica-cavity are 3.36 pm/kPa and 14.36 pm/℃, respectively. Moreover, the temperature and air pressure cross-sensitivity can be reduced by using a sensitivity coefficients matrix of two cavities. With the advantages of compact size, easy fabrication, and all-fiber structure, the proposed sensor is potential candidate for practical applications.
关键词： Air pressure and temperature measurement,Fabry-Perot interferometer
更新于2025-09-09 09:28:46
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Contactless Liquid Interface Measurement based on a Hollow Coaxial Cable Resonator
摘要： This paper reports a contactless liquid interface sensor based on a microwave Fabry-Perot resonator. A hollow coaxial cable is employed as the sensing platform, in which air serves as the dielectric layer. By shorting the inner and outer conductors of the hollow coaxial cable, two reflectors with high reflectivity (> 70%) are created to form a microwave Fabry-Perot resonator. An open groove is engineered on the resonator allowing the electromagnetic wave to interact with the medium outside the cavity. When a container, filled with different layers of liquids, is placed near the groove edge of the sensor, the leaked electromagnetic wave will interact with the liquids inside the container. By correlating the relative permittivity of the liquid mixture to the resonant frequency of the Fabry-Perot resonator, the interface between different liquids can be unambiguously determined. In the demonstration experiment, the water-oil interface and oil-ethanol interface were measured. Meanwhile, the sensor could also be employed to measure the relative permittivity of different liquids in a non-contact fashion. The presented sensor offers a robust, cost-effective, and real-time configuration for contactless liquid interface detection, which has potential applications in the oil and chemical industries.
关键词： hollow coaxial cable,Fabry-Perot resonator,Liquid interface,contactless measurement
更新于2025-09-04 15:30:14