The three dimensional cavity resonator

The response of a three dimensional cavity to an external excitation is examined. By using the technique of matched asymptotic expansions the full response curve is predicted, and the low frequency Helmholtz mode is studied in some detail. The results are compared with those of Rayleigh and others to reveal some interesting differences.     

An anisotropic metamaterial-based rectangular resonant cavity

Resonance properties of a rectangular resonant cavity filled with an anisotropic metamaterial bilayer are investigated. Different from the isotropic case and the one-dimensional resonator, the resonance properties in such a cavity are closely related to the dispersion relation of the anisotropic medium. Three cases including six subcases of different combinations of metamaterials are discussed and it is found that subwavelength resonance modes may occur in all subcases. Particularly, the relation between resonance modes and the transverse cavity width is investigated, and calculated results show that there are infinite subwavelength resonance modes as the transverse cavity width approaches zero. Requirements of the material and geometry parameters to construct a subwavelength resonant cavity are revealed by theoretical analysis, which demonstrates that this kind of subwavelength resonator brings more design flexibility and tolerance. PACS 78.70.Gq; 81.05.Zx; 84.40.Ba     

Exact solution of resonant modes in a rectangular resonator

The resonant modes of rectangular two-dimensional optical resonators were analyzed exactly. Based on the characteristics of the Bessel function, the resonant frequencies of the rectangular microcavities are expressed in a simple way. In addition, a simple rule to judge when the finite length of a rectangular resonator can be considered infinite is given in realistic applications. The solution that is presented should be useful in possible applications of the rectangular resonators as filters for dense wavelength-division multiplexing.     

Sensitivity of surface resistance measurement of HTS thin films by cavity resonator, dielectric resonator and microstrip line resonator

Microwave surface resistance (R _s) of silver-doped YBa₂Cu₃O_7-δ (YBCO) thin film, deposited by laser ablation technique on 10 mm × 10 mm LaAlO₃ substrate, has been measured by resonant techniques in the frequency range from 5 GHz to 20 GHz. The geometrical factor of the sample and the resonator has been determined theoretically by the knowledge of the electromagnetic field distribution in the resonators. The microwave surface resistance of the superconducting sample is then extracted from the measured Q value as a function of temperature. The sensitivity of the R _s measurement, that is, the relative change in the Q value with the change in the R _s value is determined for each resonator.     

Subwavelength rectangular cavity partially filled with left-handed materials

In this paper, we present the electromagnetic analysis of a rectangular cavity partially filled with a left-handed material slab. Our theoretical investigation shows that there exist novel resonant modes in the cavity, and such a cavity becomes a subwavelength cavity. The eigenvalue equation of the cavity is derived and the resonant frequencies of the novel modes are calculated by using numerical simulation. We also discuss the stability of the novel resonant modes and show the best condition under which a useful rectangular cavity of subwavelength dimensions with tolerable stability is obtained.     

The acoustic modes of a two-dimensional rectangular cavity

A theoretical study of the acoustic modes of a two-dimensional rectangular cavity is presented in this paper. It is found that for cavities with length to depth ratio of unity or larger the natural modes are heavily damped due to acoustic radiation. Numerical results for lower order modes are given. The physical significance of strong radiation damping on the onset of cavity tones induced by outside flow at low Mach number is discussed.     

Millimeter wave source in the rectangular waveguide cavity

This paper describes a power combiner of solid—state millimeter wave in rectangular cavity. The operating frequency is about 50 GHz. And the sources of excitation are GaAs Gunn deodes. Final presents the performance parameter, combining efficiency, tuning range, frequency drift, and FM noise, etc. This paper also presents a millimeter wave source of rectangular waveguide cavity. Using an exellent algorithm to design rectangular waveguide cavity of power combimer. The algorithm gives the mathematial model, on the basis of the mathematial model, using CAD of PC microcomputer to design the parameters of the cavity. This paper presents a program of CAD of micocomputer.     

A cavity experiment to search for hidden sector photons

We propose a cavity experiment to search for low mass extra U(1) gauge bosons with gauge-kinetic mixing with the ordinary photon, so-called paraphotons. The setup consists of two microwave cavities shielded from each other. In one cavity, paraphotons are produced via photon–paraphoton oscillations. The second, resonant, cavity is then driven by the paraphotons that permeate the shielding and reconvert into photons. This setup resembles the classic “light shining through a wall” setup. However, the high quality factors achievable for microwave cavities and the good sensitivity of microwave detectors allow for a projected sensitivity for photon–paraphoton mixing of the order of χ∼¹⁰⁻¹²–¹⁰⁻⁸$\chi \sim {10}^{\mathrm{-12}}\text{–}{10}^{\mathrm{-8}}$, for paraphotons with masses in the μeV to meV range—exceeding the current laboratory and astrophysics-based limits by several orders of magnitude. Therefore, this experiment bears significant discovery potential for hidden sector physics.     

Quasi-monolithic ring resonator for efficient frequency doubling of an external cavity diode laser

A quasi-monolithic second-harmonic-generation ring resonator assembled with miniaturized components is presented. The ring contains a 10-mm-long bulk periodically poled lithium niobate crystal for second-harmonic generation, four plane mirrors and two gradient-index lenses. All parts are mounted on a glass substrate with an overall size of 19.5 mm×8.5 mm×4 mm. As pump source a broad-area laser diode operated in an external resonator with Littrow arrangement is utilized. This external cavity diode laser provides near diffraction limited, narrow-bandwidth emission with an optical output power of 450 mW at a wavelength of 976 nm. Locking of the diode laser emission to the resonance frequency of the ring cavity was achieved by an optical self-injection locking technique. With this setup more than 126 mW of diffraction-limited blue light at 488 nm could be generated. The opto–optical conversion efficiency was 28% and a wall plug efficiency better than 5.5% could be achieved.     

A novel phase locked cavity resonator for B/A measurements in fluids

A new technique for the measurement in fluids of the acoustic non-linearity parameter B/A is presented, together with measured B/A values for several fluids. The non-linearity parameter is measured by phase locking radial modes within a PZT cylinder. The system, which implements the isentropic phase technique, uses continuous wave phase locking to measure the change in sound velocity that is typically associated with a change in ambient pressure under constant entropy. The method provides a means of measuring B/A in vitro both accurately and simply without the typical problems involved in time-of-flight systems. Fluid samples can remain small due to the nature of the cavity resonator, so the system is well suited to small volume, biological samples.     

Quantum dynamics of a mechanical resonator driven by a cavity

We explore the quantum dynamics of a mechanical resonator whose position is coupled to the frequency of an optical (or microwave) cavity mode. When the cavity is driven at a frequency above resonance the mechanical resonator can gain energy and for sufficiently strong coupling this results in limit-cycle oscillations. Using a truncated Wigner function approach, which captures the zero-point fluctuations in the system, we develop an approximate analytic treatment of the resonator dynamics in the limit-cycle regime. We find that the limit-cycle oscillations produced by the cavity are associated with rather low levels of energy fluctuations in the resonator. Compared to a resonator at the same temperature which is driven by a pure harmonic drive to a given average energy, the cavity-driven oscillations can have much lower energy fluctuations. Furthermore, at sufficiently low temperatures, the cavity can drive the resonator into a non-classical state which is number-squeezed.     

325 MHz低β半波长谐振腔设计

对质子加速器中半波长谐振腔（HWR）型的设计进行了研究,完成一种新型HWR超导腔的初步设计。通过对超导腔设计方法及设计原则的研究,结合相关半波长谐振腔的研究现状,充分利用电磁设计软件的功能,对325 MHz低大孔径的半波长谐振腔进行了设计研究。在建模中,针对腔体的不同部位进行比较分析,优化模型形状;在计算中,采用新型有限元网格,使计算快速而结果稳定;在后处理中,使用参数扫描,实现了腔形参数优化;在腔形分析中,计算了二次电子倍增效应,验证了腔体形状的可行性。通过此设计过程,使所设计的新型为0.12的HWR腔具有较好的电磁参数,满足质子加速器的要求,并可应用到实际工程中。     

Eigenfrequency of a Helmholtz resonator at the wall of a rectangular duct

The eigenfrequency of a Helmholtz resonator fixed at the wall of a rectangular duct is estimated. Special attention is given to determining the attached length of the resonator neck as viewed from the duct. The dependences of the attached neck length and the eigenfrequency on the duct configuration are analyzed. Theoretical results are compared with the data of numerical calculations performed by the finite-element method.     

An ultra-small cavity resonator loaded with LHM and RHM layers

In this paper, an ultra-small cavity resonator (USCR) loaded with left-handed metamaterial (LHM) and right-handed material (RHM) layers is designed using a novel miniaturization approach. The resonant behavior is successfully observed, and the dimensions of the USCR are only 4.58 mm × 5.08 mm × 2.29 mm at the dominant resonance frequency of 10.3 GHz. Through the field distribution calculation, we confirmed that the miniaturization of the USCR arises from the left-handed property of the LHM. For a practical application, a miniaturized filter with overall length of 10.19 mm consisting of two USCRs is designed to confirm the frequency-selective characteristics. Results show that the filter has some narrow pass bands, which correspond to the resonant modes of the electromagnetic resonance in the USCR, and the insertion loss at the dominant resonance frequency of the USCR is as low as 0.65 dB. Moreover, the filtering characteristics of the filter can be controlled by changing its feeding loop positions in the USCR. PACS 78.70.Gq; 81.05.Zx; 84.40.Ba