Open Fabry-Perot Research Articles

In-line fiber optic optofluidic sensor based on a fully open Fabry-Perot interferometer

In-line fiber optic optofluidic sensor based on a fully open Fabry-Perot interferometer

Fabry-perot interferometers with resin scaffolders for high sensitivity temperature sensing

This study explores the development of an innovative Fabry-Perot Interferometer (FPI) designed for temperature sensing and environmental monitoring. The device is constructed by embedding optical fibers within a 3D-printed resin scaffold, forming a structure with an open Fabry-Perot cavity. Intended as an integral component of Cyber-Physical-Social Systems (CPSS), this FPI structure aims to enhance the system’s capacity to sense changes in external environmental conditions. Within the CPSS context, the FPI offers several advantages, including simple manufacturing processes, low production costs, and high sensitivity. These benefits contribute to providing precise environmental feedback to the system, which is essential in implementing effective security and privacy protection strategies. Experimental evaluations have shown that the FPI exhibits a high linear sensitivity of 14.330 nm/°C within a temperature range of 34.9°C–38.5°C, confirming its potential for application in CPSS for temperature monitoring and environmental sensing.

Interaction between light and single quantum-emitter in open Fabry-Perot microcavity

The interaction between light and matter has attracted much attention not only for fundamental research but also for applications. The open Fabry-Perot cavity provides an excellent platform for such a study due to strong optical confinement, spectral and spatial and tunability, and the feasibility of optical fiber integration. In this review, first, the basic properties of open Fabry-Perot cavities and the fabrication techniques are introduced. Then recent progress of weak coupling, strong coupling and bad emitter regimes is discussed. Finally, the challenges to and perspectives in this respect are presented.

Surface plasmon polariton laser based on a metallic trench Fabry-Perot resonator.

Recent years have witnessed a growing interest in the development of small-footprint lasers for potential applications in small-volume sensing and on-chip optical communications. Surface plasmons-electromagnetic modes evanescently confined to metal-dielectric interfaces-offer an effective route to achieving lasing at nanometer-scale dimensions when resonantly amplified in contact with a gain medium. We achieve narrow-linewidth visible-frequency lasing at room temperature by leveraging surface plasmons propagating in an open Fabry-Perot cavity formed by a flat metal surface coated with a subwavelength-thick layer of optically pumped gain medium and orthogonally bound by a pair of flat metal sidewalls. We show how the lasing threshold and linewidth can be lowered by incorporating a low-profile tapered grating on the cavity floor to couple the excitation beam into a pump surface plasmon polariton providing a strong modal overlap with the gain medium. Low-perturbation transmission-configuration sampling of the lasing plasmon mode is achieved via an evanescently coupled recessed nanoslit, opening the way to high-figure of merit refractive index sensing of analytes interacting with the open metallic trench.

Room-temperature exciton-polaritons with two-dimensional WS2.

Two-dimensional transition metal dichalcogenides exhibit strong optical transitions with significant potential for optoelectronic devices. In particular they are suited for cavity quantum electrodynamics in which strong coupling leads to polariton formation as a root to realisation of inversionless lasing, polariton condensation and superfluidity. Demonstrations of such strongly correlated phenomena to date have often relied on cryogenic temperatures, high excitation densities and were frequently impaired by strong material disorder. At room-temperature, experiments approaching the strong coupling regime with transition metal dichalcogenides have been reported, but well resolved exciton-polaritons have yet to be achieved. Here we report a study of monolayer WS2 coupled to an open Fabry-Perot cavity at room-temperature, in which polariton eigenstates are unambiguously displayed. In-situ tunability of the cavity length results in a maximal Rabi splitting of ħΩRabi = 70 meV, exceeding the exciton linewidth. Our data are well described by a transfer matrix model appropriate for the large linewidth regime. This work provides a platform towards observing strongly correlated polariton phenomena in compact photonic devices for ambient temperature applications.

Fabry-Perot microcavity for diamond-based photonics

Open Fabry-Perot microcavities represent a promising route for achieving a quantum electrodynamics (cavity-QED) platform with diamond-based emitters. In particular, they offer the opportunity to introduce high purity, minimally fabricated material into a tunable, high quality factor optical resonator. Here, we demonstrate a fiber-based microcavity incorporating a thick (> 10 {\mu}m) diamond membrane with a finesse of 17,000, corresponding to a quality factor Q ~ $10^6$. Such minimally fabricated, thick samples can contain optically stable emitters similar to those found in bulk diamond. We observe modified microcavity spectra in the presence of the membrane, and develop analytic and numerical models to describe the effect of the membrane on cavity modes, including loss and coupling to higher-order transverse modes. We estimate that a Purcell enhancement of approximately 20 should be possible for emitters within the diamond in this device, and provide evidence that better diamond surface treatments and mirror coatings could increase this value to 200 in a realistic system.

Modern Resonator Spectroscopy at Submillimeter Wavelengths

Classical resonator spectroscopy methods have been realized for the first time in the submillimeter wave range. A resonator spectrometer was developed earlier at the IAP RAS on the basis of an open Fabry-Perot resonator excited by the radiation of a backward wave oscillator whose frequency is stabilized by the phase lock loop system. This spectrometer is successfully used for high-precision measurements of the dielectric properties of solid, liquid, and gaseous dielectrics as well as for the metal and coating reflection measurements in the 36-370 GHz range. In this paper, we report an extension of the upper limit of the spectrometer operation frequency to 520 GHz. Features of operation of the main spectrometer systems in the extended frequency range are analyzed. The broadband measurements of absorption in modern MPCVD diamonds are presented. A continuous record of the absorption spectrum of the laboratory atmosphere in the 350-500 GHz range obtained for the first time by the high-sensitivity microwave method is demonstrated. Further prospects for extension of the spectrometer range to terahertz frequencies are discussed.

Mathematical modeling of an open microcavity with a layer of metamaterial

We investigate the properties of an open Fabry-Perot microcavity containing a layer of metamaterial with a negative refractive index. Numerical simulation of this cavity is performed using an original program package based on the FDTD scheme, with allowance for the frequency dispersion of the media and the UPML absorbing boundary conditions. We demonstrate that waveguide eigenmodes with arbitrary profiles exist in such a cavity and the metamaterial lowers diffraction losses considerably.

Methods for investigating thin dielectric films in the millimeter range

An original method based on determining the characteristics of open Fabry-Perot resonator modes with different polarizations is proposed for measuring parameters of dielectric plates and films with a thickness smaller than λ/2 in the millimeter and submillimeter wavelength ranges. This method is used for determining the refractive index and tanδ, as well as the thickness of films made of isotropic materials. For anisotropic films of known thickness, the method makes it possible to measure the permittivity tensor components. Popular film materials such as Teflon (polytetrafluoroethylene, PTFE), lavsan (Mylar, polyethyleneterephthalate, PETP), and polyamide with a minimal thickness of ∼5 μm are investigated. Appreciable anisotropy of roll film materials and the dependence of the dielectric properties on the thickness, which is associated with manufacturing technology, are revealed. The dependence of the refractive index and tanδ on the air humidity is investigated

Interference, Coulomb blockade, and the identification of non-Abelian quantum Hall states

We examine the relation between different electronic transport phenomena in a Fabry-Perot interferometer in the fractional quantum Hall regime. In particular, we study the way these phenomena reflect the statistics of quantum Hall quasi-particles. For two series of states we examine, one abelian and one non-abelian, we show that the information that may be obtained from measurements of the lowest order interference pattern in an open Fabry-Perot interferometer is identical to the one that may be obtained from the temperature dependence of Coulomb blockade peaks in a closed interferometer. We argue that despite the similarity between the experimental signatures of the two series of states, interference and Coulomb blockade measurements are likely to be able to distinguish between abelian and non-abelian states, due to the sensitivity of the abelian states to local perturbations, to which the non-abelian states are insensitive.

Dielectric losses in CVD diamonds in the millimeter-wave range at temperatures 300?900 K

We study losses in different CVD diamonds in the frequency range 50–210 GHz at temperatures 300– 900 K by using a high-Q open Fabry-Perot cavity. It is found that the effective activation energies determining a sharp increase in losses at high temperatures are distributed in the range 0.4–0.8 eV. We propose a formula which relates the frequency and temperature dependences of losses for different CVD-diamond specimens in the first approximation. Suggestions on the nature of these losses are put forward.

Superradiance of the polaritons of a two-level medium in a low-Q Fabry-Perot cavity

An analytical theory has been developed for the superradiance of hot polariton modes formed by an inverted two-level medium in an open low-Q Fabry-Perot cavity. A qualitative analysis is proposed for the nonlinear stage of single-mode and multimode superradiance, and its difference from unidirectional superradiance is indicated. The characteristic shapes of the pulses and the common properties of single-pulse and oscillatory regimes are discussed for a cavity of arbitrary Q, as well as the correlation and the Bragg-rescattering features of pulses emitted from the opposite ends of a sample. © 2004 Optical Society of America

Mode instability and nonlinear superradiance phenomena in open Fabry-Perot cavity

Collective spontaneous emission of discrete modes (i.e., mode superradiance or superfluorescence) in an open Fabry-Perot cavity is considered. The simultaneous emission of counter-propagating coherent pulses is associated with the instability of normal “hot” modes, even in the case of very low, but finite reflection at mirrors, beginning with R cr ⪡ 1. A role of nonlinear Bragg backscattering by a self-consistent ( λ 2 )- lattice of population inversion of active two-level medium is discussed. It is shown that the interference of inhomogeneous counter-propagating waves alters essentially the space-time dynamics of inversion exhaustion and the profile of superradiance pulse, compared with the mean field and the unidirectional models. The novel nonlinear equation of mode superradiance in an open cavity is derived. The approximate analytic solution to the equation is found. Various regimes of superradiance are analyzed on the basis of this solution and compared with numerical simulations.

Theory of waveguide laser resonators with small curvature mirrors

A theoretical investigation into the eigenmodes of a waveguide resonator with small curvature mirrors is presented. Field differential equations are derived. Eigenfunctions and eigenvalues are given approximately. Cut-off curvatures are obtained. A criterion which can help to distinguish between a waveguide laser resonator and an open Fabry-Perot one is proposed.

Quantitative millimetre wave spectroscopy. part II: Determination of working conditions in an open Fabry-Perot cavity

A confocal Fabry-Perot frequency modulated cavity spectrometer of quality factor 1.25 × 10 5 operating inside a chamber maintained at ambient temperature and pressure of 1 Pa to 1 KPa was employed for spectrometric measurements in the region of 72 GHz and 140 to 160 GHz. The spectrometer used a spatial filter to suppress unwanted, non-axial modes. The solid state microwave source frequency was derived from a phase-locked frequency synthesizer and detection was by a liquid helium cooled bolometer. Transitions in acrylonitrile, formaldehyde, and sulphur dioxide were studied demonstrating parts per million sensitivity for these species in atmospheric samples, whilst carbonyl sulphide samples were detected at sub-parts per million concentration. The effect of pressure on line intensities was studied in order to determine the optimum operating regime. It was found that the technique was not restricted to the 5–50 Pa region characteristic of centimetric wave spectroscopy, but was able also to function in the 0.1 to 1 KPa regime. Furthermore the intensities in this latter region were found to be not critically dependent on sample pressure. A treatment of the effect of pressure and depth of frequency modulation on absorption signals was carried out and the resulting theory applied to the observed intensity-pressure relationships. There was good quantitative agreement between the frequency modulation depth and cavity response characteristics and qualitative agreement between the pressure, frequency modulation and spectral line intensity characteristics. It became clear that the possibility of power saturation, coupled with the non-uniform power distribution within the cavity, was affecting the fits of theoretical curves to the observed data, and that taking this into account produced marked improvement in the fits. Nonetheless the treatment permitted some practically useful conclusions: at low modulation depths and pressures, the sharp spectral absorption peak makes identification of the target species easy, but extraction of quantitative information more difficult, as the intensity will depend critically on the power level in the cavity. At pressures in the 100 Pa region however, the signal obtained is maximal, power broadening minimal and comparative intensity measurements possible over a range of sample species and concentrations.

A novel high-field/high-frequency EPR and ENDOR spectrometer operating at 3 mm wavelength

A high-field/high-frequency EPR and ENDOR system operating at 3 mm wavelength is described. The probe-head designs of two different resonator types, i.e. an open Fabry-Perot resonator and a cylindrical TE011 cavity, are presented in detail. The advantages and limitations of high-field/high-frequency EPR and ENDOR spectroscopy are demonstrated for selected examples. The performance data of the spectrometer suggest that it will be very useful for broad applications in physics, chemistry and biology.

Large mode-size fibre Fabry-Perot interferometers

We show that fibre-coupled open resonator Fabry-Perot interferometers can be made with reduced insertion loss due to diffraction by using fibre with slightly larger mode size. For a 50% increase in mode size, the insertion loss is reduced by 3–4dB for a 7μm-long resonator at 1.5μm wavelength.

The Optically Pumped Caesium Fountain: 10-15 Frequency Accuracy?

Velocity-related problems like Doppler shifts, distributed cavity phase-shift and pulling by neighbouring transitions are presently the limiting factors in the accuracy of Cs beam primary frequency standards. The use of slow atoms appears to be the only fundamental solution to these problems, and new kinds of standards are being investigated, based on different ideas for trapping and cooling down the atoms. The thirty-year-old idea of gravitational trapping was abandoned after a short trial due to bad signal-to-noise ratio in a Cs fountain beam which made use of magnetic state selection and hot wire detection. In this paper it is shown that optical state selection and detection, in conjunction with an open Fabry-Perot type resonator, can make that old idea very attractive again. A rough design sketch is outlined and a detailed analysis is given of the various uncertainty sources affecting the frequency of a fountain Cs standard, while problems which need further examination are pointed out.

Effect of a dielectric film on the characteristics of an open Fabry-Perot resonator cavity

It is demonstrated that placing a thin dielectric film inside the cavity of an open Fabry-Perot resonator, at an angle to its axis, will remove the polarizational degeneracy of the principal TEMq00 oscillation modes. Upon excitation of such a resonator cavity by a plane wave, the reflected electromagnetic field is in general elliptically polarized. The shape of the resonance curve depends on the thickness of that film, on its orientation inside the cavity, on the conditions under which the cavity has been excited, and on the conditions under which the reflected signal appears in the receiver. Changing the polarization plane of the incident plane wave does not result in a smooth variation of the resonator Q factor.

Fabry-Perot laser interferometry to measure refractive index or thickness of transparent materials

By introducing a transparent plane parallel plate into an open Fabry-Perot cavity and counting the change in the interference order while the plate is rotated, it is possible to measure the thickness or refractive index of the material with a high degree of accuracy. The method of multipass interferometry can be applied by using a He-Ne laser of 632.8 nm wavelength.