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Three-Way Multiple-Mode Cavity Filtering Crossover for Narrowband and Broadband Applications
摘要： In this paper, the design of a cavity crossover with three intersecting channels is presented. The three fundamental modes of a cavity resonator, namely, TE011, TE101, and TM110 modes, are adopted to resonate at each of three channels, respectively. Due to the modal orthogonality of these fundamental modes, high isolation among three channels can be achieved. Two kinds of crossovers, for narrowband and broadband applications, are presented. For the narrowband case, the proposed crossover resonates at 2.91 GHz with the fractional bandwidth of 1.4%. For the broadband case, the proposed crossover resonates at 3 GHz with the fractional bandwidth of 24%. The isolations of both designs reach more than 50 dB. For a proof of concept, the broadband example of the cavity crossover structures is fabricated and measured. A good agreement between the simulated and the measured results verifies the accuracy of the proposed design methodology.
关键词： slot coupling,multiple mode,Broadband,three channel,cavity crossover,triple-mode rectangular cavity,resonator (TMR)
更新于2025-09-23 15:22:29
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Electromagnetic Wave Absorbers (Detailed Theories and Applications) || Measurement Methods on <scp>EM</scp> ‐Wave Absorbers
摘要： In order to deepen our knowledge of the electromagnetic (EM)-wave absorber design, it becomes important to accurately know the material characteristics and the characteristics of the absorber itself. In this chapter, after describing the measurement methods of material constants, the measurement methods of EM-wave absorber characteristics are described. In particular, we intend here to explain in detail the measurement methods of material constants, including conventional methods together with analytical methods. In Section 7.1, as the methods of measuring the material constants for wave-absorbing materials, the methods of using a rectangle waveguide, coaxial waveguide, and microwave resonators are described. First, measurement methods based on the standing-wave method using the rectangular waveguide and coaxial waveguide are studied. Second, in the microwave resonator methods for cylindrical cavities, the measurement methods of dielectric constant and conductivity in the lossless case, complex permittivity, and complex permeability are investigated theoretically. In Section 7.2, as a method for measuring the EM-wave absorber characteristics, the method of TEM mode transmission lines such as coaxial waveguides, strip lines, and TEM cells are examined first. Then, the waveguide method, as a special case, is described, along with space standing-wave methods.
关键词： cavity resonator method,EM-wave absorber,TEM mode transmission line,material constants,measurement methods,waveguide method,space standing-wave method,standing-wave method
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Wavelength Stabilized External Cavity Quantum Cascade Lasers using Cavity Resonator Integrated Grating Filters
摘要： External cavity diode lasers (ECDLs) are a standard way of building single-mode and narrow-linewidth sources [1], while keeping the intrinsic benefits of semiconductor lasers like compactness, low-cost and high-modulation capability. Traditional ECDLs design uses a bulk diffraction grating in Littrow or Littman/Metcalf configurations. In this paper, we report on the use of recently demonstrated MIR Cavity Resonator Integrated Grating Filters (MIR-CRIGFs) [2] to implement an alternative configuration using a compact and stable cat’s-eye configuration. The external cavity under study is made of a 4.5 μm QCL laser grown on InP substrate with an HR coating on the rear facet and an optimized AR coating on the front facet. An intracavity lens (f=1.87 mm) images the AR coated facet onto a CRIGF used both as a cavity end-mirror and a spectral filter. The total cavity length is short, estimated around 4.2 cm. The initial cavity alignment is straightforward thanks to the high sensitivity of the QCL gain chip to optical feedback, monitored through injection voltage. On figure 1, the different CRIGFs are clearly visible (large white rectangles arranged on two 6x10 matrices with varying geometrical parameters). CRIGFs where the central GC appears as a dark narrow vertical stripe are the one inducing the highest optical feedback in the QCL. They correspond to the CRIGFs spectrally matched with the QCL gain medium and able to stabilize the emitted frequency.
关键词： External cavity diode lasers,MIR Cavity Resonator Integrated Grating Filters,wavelength stabilisation,QCL laser
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - Atlanta, GA, USA (2019.7.7-2019.7.12)] 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - Millimeter-Wave Triple-Resonance Substrate Integrated Waveguide Cavity-Backed Slot Antenna With Cavity Resonator
摘要： A triple-resonance substrate integrated waveguide (SIW) cavity-backed slot antenna using two cavity resonators is proposed in this paper. The proposed antenna consists of a radiation area and a cavity resonator area. In order to generate triple resonance, two cavity resonators are designed in the cavity resonator area. The working mechanism of the proposed antenna is explained with its electric field distributions.
关键词： millimeter wave,cavity-backed slot antenna,triple resonance,cavity resonator
更新于2025-09-11 14:15:04
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Realization of sharp visible WGM lasing from Sm<sup>3+</sup>:ZnO micro-spheres fabricated by laser ablation technique
摘要： In this paper, the whispering gallery mode lasing from Sm3+ doped ZnO micro-spheres operating in the visible wavelength range 550-750 nm is studied. Highly smooth and crystalline Sm3+:ZnO micro-spheres of various diameters were synthesized by simple laser ablation of sintered target in air. The dopant concentration has been restricted within the solid solubility limit of 1 mol%. The Sm3+ ion substitution in ZnO matrix results in the formation of inter-band levels by the characteristic 4f level of Sm3+ in the forbidden gap of ZnO. Thus, when the micro-spheres are excited with 488 nm, four major visible emissions associated with Sm3+ f ? f transitions namely, transitions from 4G5/2 to its low-lying multiplets of 6HJ (J = 5/2, 7/2, 9/2 and 11/2), are obtained. These emissions are coupled to the WGMs of the Sm3+:ZnO micro-cavity resulting in sharp resonances in the visible region. Interestingly, the resonances are found to be lasing above lower pumping powers. The Q-factor obtained is of the order of 103 for spheres of size ranging 1.8-10.2 μm. The best Q-factor obtained is 3744 for 561.61 nm peak (FWHM 0.15 nm) from 8 μm sphere. These results would ?nd a place in visible range lasing and sensor applications.
关键词： Q-factor.,visible renge,cavity resonator,WGM resonances,lasing,Microsphere
更新于2025-09-11 14:15:04
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Strong coupling of a two-dimensional electron ensemble to a single-mode cavity resonator
摘要： We investigate the regime of strong coupling of an ensemble of two-dimensional electrons to a single-mode cavity resonator. In particular, we realize such a regime of light-matter interaction by coupling the cyclotron motion of a collection of electrons on the surface of liquid helium to the microwave field in a semiconfocal Fabry-Pérot resonator. For the corotating component of the microwave field, the strong coupling is pronouncedly manifested by the normal-mode splitting in the spectrum of coupled field-particle motion. We present a complete description of this phenomenon based on classical electrodynamics, as well as show that the full quantum treatment of this problem results in mean-value equations of motion that are equivalent to our classical result. For the counterrotating component of the microwave field, we observe a strong resonance when the microwave frequency is close to both the cyclotron and cavity frequencies. We show that this surprising effect, which is not expected to occur under the rotating-wave approximation, results from the mixing between two polarization components of the microwave field in our cavity.
关键词： microwave field,classical electrodynamics,cavity resonator,normal-mode splitting,two-dimensional electrons,rotating-wave approximation,Fabry-Pérot resonator,strong coupling,quantum treatment,cyclotron motion
更新于2025-09-04 15:30:14