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对准光学谐振腔诊断等离子体的传统诊断方法进行了改进,提出一种可用于诊断瞬态等离子体的实时诊断方法。通过实验证明,矢量网络分析仪点频测试(CW Sweep)对信号相位变化的测量速度足够快,可以跟上等离子体鞘套和尾迹的变化速度,因此利用该方法诊断等离子体鞘套和尾迹是可行的。通过对诊断系统性能的评估,表明诊断装置具有较高的实时性,对等离子体电子浓度有较宽的测量范围,测量范围可达10-1~1015m-3。     

Nonlinear dynamics in a Fabry-Perot resonator

We develop a general formalism to describe the dynamical behavior of an ensemble of two-level systems in a Fabry-Perot cavity. Our main result is a set of space and time-dependent, integro-differential equations for the slowly varying radiation and atomic variables, which we derive through a precise analysis of the slowly-varying amplitude approximation in the presence of counter-propagating fields. With the help of new and properly chosen variables we recast these equations in a form that makes their boundary conditions formally identical to those of an ideal Fabry-Perot resonator, and introduce in a natural way a modal structure even for systems with arbitrary mirror reflectivity. We derive simplified forms of these equations in the uniform field limit and within the more general single-frequency approximation. Finally, we extend our formulation to include driven systems such as optically bistable devices and the laser with an injected signal.     

Optical pulse narrowing using a Fabry-Perot resonator

An optical pulse narrowing technique by spectral windowing using a Fabry-Perot resonator is demonstrated. A 150 ps pulse from a mode-locked Ar ion laser has been compressed by a factor of 2.7.     

Nonlinear all-photonic-crystal Fabry-Perot resonator with angle-independent bistability

We propose a nonlinear all-photonic-crystal (PhC) Fabry-Perot cavity tuned to the subdiffractive regime of the interior PhC, and we study angular-resolved nonlinear propagation of monochromatic plane wave excitations. With rigorous numerical simulations, we show that, for sufficiently large negative pump detunings and a focusing nonlinearity, the transmitted field has a bistable dependence on the pump field. Moreover, we reveal that, in contrast to a homogeneous resonator for different inclinations, the hysteresis curve is virtually unchanged for a fairly wide angular range. This may pave the way for obtaining novel kinds of nonlinear localized solutions in driven nonlinear resonators.     

Optical information processing by the Fabry-Perot resonator

Properties of the Fabry-Perot resonator as a part of an optical imaging system are discussed from the point of view of optical information theory. Information capacity of the system is derived and expressed in terms of the number of degrees of freedom of the optical wave field at the output. It is pointed out that the Fabry-Perot resonator is well suited for processing of image signals having a periodic structure.     

A novel receiver-transmitter metasurface for a high-aperture-efficiency Fabry-Perot resonator antenna

This paper presents a novel coupled receiver-transmitter metasurface (MS) which is used to realize a high-aperture-efficiency Fabry-Perot resonator antenna. The unit cell of the MS adopts a slot-coupling procedure to realize energy transmission from the receiver patch to the radiator patch. This approach makes it easier to independently control the transmission magnitude and phase. Based on this characteristic, the transmission coefficients of different unit cells on the MS can be optimized by a genetic algorithm. Then, nearly uniform electric amplitude and phase distribution across the aperture field of the antenna are achieved. Therefore, the gain and aperture efficiency of the antenna are improved. A prototype of the optimized antenna is fabricated and measured to validate the design. The measured gain of the fabricated antenna reaches 17.3 dBi with an aperture efficiency of 94.5%. A higher aperture efficiency is obtained with the proposed antenna which has a low profile and simple structure.     

Asymmetric Fabry-Perot resonator containing an arbitrary inhomogeneous layer

A new method for determining the transmission and reflection coefficients for an arbitrarily polarized electromagnetic wave incident obliquely on an inhomogeneous insulating layer inside an asymmetric Fabry-Perot resonator is proposed. Algebraic relationships between these coefficients for a layer bounded by different homogeneous semi-infinite media and for the same layer in a vacuum are derived. Three examples corresponding to real situations are analyzed, and the results of corresponding numerical calculations are discussed.     

SBS gain-based slow-light system with a Fabry-Perot resonator

We present a method to improve the delay performance of stimulated Brillouin scattering (SBS) gain systems by combining them with Fabry-Perot (FP) filters under practical resource and data-fidelity constraints. We optimize the delay performance of four different systems: a single-line gain system (G1-system) combined with one FP filter (G1F1-system) and two FP filters (G1F2-system) and a double-line gain system (G2-system) combined with one FP filter (G2F1-system) and two FP filters (G2F2-system). We show that combining the gain-based slow-light system with FP filters can create a flat-top transmission spectrum and increases the phase slope. The G1F2-system provides a fractional delay 2.3 times that of the G1-system, whereas a G2F2-system improves the fractional delay 1.82 times that of the G2-system at a given bit rate under the same resource and data-fidelity constraints.     

Stability diagram of higher modes of the Fabry-Perot resonator

We have numerically calculated the stability diagram of the higher modes of the Fabry-Perot resonator by direct diagonalization of the Fox-Li equation. The diagram has an exotic behavior in the small Fresnel number region and its higher modes in our numerical experiments.     

Transmission characteristics of a Fabry-Perot etalon-microtoroid resonator coupled system

The transmission spectra of a Fabry-Perot etalon coupled to a microtoroid resonator are studied theoretically and experimentally. The resonance line shapes depend strongly on the resonance wavelength detuning and coupling strength between the two resonators. A wide variety of line shapes, ranging from a single to triple peaks, symmetric to asymmetric Fano-like peaks, and notches were predicted and observed experimentally. The capability to modify the spectral line shapes by tuning the coupling between or losses of two resonators may find applications in optical filtering, switching, sensing, and dispersion engineering.     

Spectral characteristics of a Fabry-Perot resonator with controlled gyrotropy

The propagation of light through a system consisting of two naturally gyrotropic layers placed in a magnetic field with an isotropic layer in between is considered. The effect of gyrotropy on the interference amplification of light in a nonreciprocal Fabry-Perot resonator is studied. It is shown that, at normal incidence of light, the system offers a high controllable rotatory power and a high transmissivity and also exhibits no polarization ellipticity.     

High sensitivity HCN laser interferometer for plasma electron density measurements

This paper describes a high sensitivity 337 μm HCN laser interferometer for plasma electron density measurements. The plasma phase shift is transferred to a low frequency signal obtained by slightly shifting the frequency of the 337 μm radiation in the reference beam of the interferometer. The frequency shift is produced by diffracting the radiation of a cylindrical rotating blazed grating. A phase shift is deduced from the time variation of the zero crossings of the low frequency signal, giving a result which is independent of amplitude fluctuations. Using pyroelectric detectors, the interferometer has a time resolution of 100 μsec and a sensitivity of 10^-2 fringe.     

Nonlinear Fabry-Perot resonator with a silicon photonic crystal waveguide

We derive an equation that describes the nonlinear operation of a Fabry-Perot resonator with a large group index waveguide. Specifically, a silicon photonic crystal microcavity with two-photon-excited free carrier nonlinearity and Kerr nonlinearity is assumed. The equation clearly explains the bistability of the device and the reduction of the required pump energy for a specific nonlinear phase shift at an appropriate phase detuning from the resonance. We present a simple procedure to predict the required optical pump energy for the modulation and the resulting modulation depth by use of the equation and the device parameters.     

Modes in the Fabry-Perot resonator with the Kerr nonlinearity

Summary The symmetric modes in the cavity of Fabry-Perot type filled by the medium with the Kerr nonlinearity are constructed. The field appears to be double periodic along the longitudinal axis.

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Riassunto Si costruiscono i modi simmetrici nella cavità del tipo di Fabry-Perot riempita dal mezzo con la non linearità di Kerr. Il campo risulta doppiamene periodico lungo l’asse longitudinale.

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Резюме Конструируются симметричные моды в резонаторе Фабри-Перо, заполненном средой с нелинейностью Керра. Оказывается, поле имеет двойную периодичность вдоль продольной оси.

     

A nanometric plasmonic waveguide filter based on Fabry-Perot resonator

A compact nanometric surface plasmon polariton Fabry-Perot filter based on three metal-insulator-metal (MIM) waveguides is proposed and studied. The characteristics of this SPP band pass filter are analyzed by the finite difference time domain method and the Fabry-Perot resonance model. The results show that the resonance wavelengths of the pass bands can be linearly changed by the resonant cavity length, and the transmission ratios of the pass bands can be varied by altering the gaps between the MIM waveguides. The metal loss and dispersion effects on the SPP filter's spectra are considered as well. This kind of simple filter is very promising for high density SPP waveguide integrations.     

Procedure for phase discrimination applicable to homodyne reflectometers for plasma density measurements

A phase discrimination method for homodyne reflectometers applied to plasma density fluctuations is proposed and tested in the laboratory simulating the plasma fluctuations by a vibrating metallic mirror.Applicability conditions for plasma measurements are established. The method can be used in broadband operation. Application to density profile measurements is also possible.     

A vibrationally compensated far infrared laser interferometer for plasma density measurements

A modulated far-infrared laser interferometer which is presently operating on the PDX experiment at Princeton is described. The interferometer geometry permits the characterization of inside D, outside D as well as circular discharges. To achieve this versatility, a titanium corner cube reflector, mounted inside the PDX vacuum vessel is used in conjunction with a second visible wavelength interferometer for vibration corrections. In addition, the use of room temperature quasi-optical Schottky diodes in the far-infrared interferometer is reported. The minimum detectable line average density of the system is 5×10¹¹ cm^–3.     

Optimization of Fabry-Perot ring resonator embedding a grating based mirror

We study a triangular arrangement of two flat mirrors and a grating mirror for coupling a \(-1{\mathrm{st}}\) diffracted order light beam into a traveling-wave intra-cavity light recirculation and out-of-cavity output, combining the \(0\,{\mathrm{th}}\) and the repeatedly diffracted secondary \(+1{\mathrm{st}}\) order beams. The thus designed and then optimized grating Fabry-Perot ring cavity demonstrates high output contrast and detection resolution for wavelength, cavity length and incidence angle.