Propagation loss measurements in semiconductor microcavity ring anddisk resonators

We report the measurement of cavity propagation losses in nearly single-mode semiconductor waveguide-coupled ring and disk microcavity optical resonators. Using a novel 10.5-μm-diameter ring resonator, we measure transverse electric (TE) and transverse magnetic (TM) field intensity losses in 0.35-μm-wide ring waveguide cavities in the 1.55-μm-wavelength region. We present the experimental results for nanofabricated AlGaAs-GaAs 10.5-μm-diameter ring and disk resonators to quantify cavity losses and to show the feasibility of these promising and robust submicron-scale devices     

Magnetic tuning of cylindrical H01δ-modedielectric resonators

The theory of magnetic tuning of cylindrical H_01δ dielectric resonators is developed. It is based on rigorous solutions to the dielectric resonator systems containing microwave ferrites. It is shown that the most effective magnetic tuning of H_01δ dielectric resonators can be accomplished by inserting a thin ferrite rod through an axial hole in the resonator. This kind of tuning utilizes the dependence of the parallel permeability tensor component μ_z on the magnetic field applied. Experiments have been performed which show that a 4% tuning range can be attained with a Q-factor of the resonant system of the order of 2000 at X -band. Using an appropriate DC magnetic field circuit, a 120 MHz tuning bandwidth has been obtained with a consumption of tuning power of about 75 mW     

Magnetoelectric effect in double-layer ferromagnetic-piezoelectric disk resonators

The magnetoelectric (ME) effect in double-layer composite disk resonators containing mechanically joined layers of magnetostrictive nickel and piezoelectric lead zirconate titanate is experimentally studied. A resonant growth of the efficiency of the ME interaction is discovered at the frequencies of the flexural and radial modes of mechanic vibrations of the resonator. Frequencies of the flexural and radial vibrations of double-layer ME resonators are calculated. The possibilities of controlling the efficiency of the ME interaction by means of selecting the thicknesses of the structure layers and the orientation of the external permanent magnetic field are demonstrated. The sensitivity of the sensors of low-frequency magnetic fields based on ME resonators is estimated.     

Whispering-gallery-like modes in square resonators

The mode frequencies and field distributions of whispering-gallery (WG)-like modes of square resonators are obtained analytically, which agree very well with the numerical results calculated by the FDTD technique and Pade approximation method. In the analysis, a perfect electric wall for the transverse magnetic mode or perfect magnetic wall for the transverse electric mode is assumed at the diagonals of the square resonators, which not only provides the transverse mode confinement, but also requires the longitudinal mode number to be an even integer. The WG-like modes of square resonators are nondegenerate modes with high-quality factors, which make them suitable for fabricating single-mode low-threshold semiconductor microcavity lasers.     

A Magnetically Tunable Microstrip IMPATT Oscillator (Short Papers)

Magnetically tunable resonators have been constructed in microstrip on a ferrite substrate. A large tuning range is obtained with an external magnetic field applied in the direction of the RF propagation, 17 MHz/Oe for magnetic fields from 0 to 30 Oe. A variable frequency microstrip oscillator which uses this effect is described; measurements made on an X-band IMPATT oscillator illustrate a tuning range from 9.4 to 10.5 GHz with an output power of 330 mW /spl plusmn/ 0.5 dB.     

Frequency splitting effect of degenerate modes in ferrite resonators

The splitting of magneto-dielectric modes frequency in disk ferrite resonators in a magnetic field is considered.Asimplified formula is obtained for estimation of the splitting magnitude. Theoretical and experimental results of the frequency splitting effect in magneto-dielectric modes in the millimeter wave range are compared. The use of the splitting of the magneto-dielectric modes frequencies as an alternative to ferromagnetic resonance in devices with magnetic frequency tuning is suggested, with values of the magnetization fields being an order of magnitude lower than for ferromagnetic resonance. The features of the splitting modes effect in different ferrite classes are investigated and it is shown that it occurs in both microwave and optical ranges. The estimated magnitude of the mode frequency splitting in the iron-yttrium garnet (YIG) transparency window can reach 9 GHz, which is comparable to the 5 GHz splitting in the millimeter range. The frequency ranges where frequency splitting effect is of practical interest are discussed. In particular, the effect in barium hexaferrite can be used both in post-resonance and pre-resonance regions, which is almost impossible for ferrogarnates and ferrospinels.     

FDTD microcavity simulations: design and experimental realizationof waveguide-coupled single-mode ring and whispering-gallery-mode diskresonators

We investigate the properties of high-Q, wide free-spectral-range semiconductor microcavity ring and disk resonators coupled to submicron-width waveguides. Key optical design parameters are characterized using finite-difference time-domain (FDTD) solutions of the full-wave Maxwell's equations. We report coupling efficiencies and resonant frequencies that include the effects of waveguide dispersion and bending and scattering losses. For diameters of 5 μm, the microcavity resonators can have Q's in the several thousands and a free spectral range of 6 THz (50 nm) in the 1.55 μm, wavelength range. Studies of the transmittance characteristics illustrate the transition from single-mode resonances to whispering-gallery-mode resonances as the waveguide width of the microring is increased to form a solid microdisk. We present nanofabrication results and experimentally measured transmission resonances of AlGaAs/GaAs microcavity resonators designed in part with this method     

Monolithically Integrated Tunable Laser Using Double-Ring Resonators With a Tilted Multimode Interference Coupler

A monolithically integrated tunable semiconductor ring laser consisting of a semiconductor optical amplifier and two ring resonators with tilted multimode interference (MMI) couplers is presented. The characteristic response of the ring resonators is discussed for various cross coupling strengths by adjusting the angle of the tilted MMI couplers. The ring laser has a wavelength tuning range of 11 nm and a sidemode suppression ratio larger than 40 dB for a cross coupling strength of 0.09. The peak power of the laser is larger than ${-}$3 dBm for chip-to-fiber coupling.      

Tunable self-seeded semiconductor disk laser operating at 2/spl mu/m

A 2 mum semiconductor disk laser with a tuning range of 35 nm and output power exceeding 500 mW is reported. The method for generating wavelength-tunable radiation is based on self-seeding the disk laser using optical feedback from a diffraction grating     

Operational features of slow-wave structures near the cutoff frequency and application of these structures for improvement of the characteristics of a cutoff magnetron

Features of the operation of electrodynamic structures near their critical frequency are considered. A technique is proposed that allows estimation of the parameters of the end cavity resonators required for correction of the field distribution of the operation mode in a cutoff magnetron and tuning the magnetron external Q factor.     

电容式RF MEMS谐振器

介绍了应用于通信领域的电容式RF MEMS谐振器及其在通信系统小型化中的优势。对电容式微机械谐振器进行了综合分析,包括基本工作过程分析、基本参数的理论分析及等效电路的分析。介绍了目前几种常用结构的谐振器,包括梳状谐振器、梁式谐振器及盘式谐振器的工作过程和谐振频率的发展空间。重点分析了谐振器的电容间隙及锚这两个重要的结构参数对谐振器性能的影响。最后,对电容式微机械谐振器存在的问题作了总结,对其发展趋势做出展望。     

Collective modes in coupled semiconductor disk lasers in the case of whispering-gallery modes

Samples of coupled semiconductor disk laser based on quantum-dimensional GaInAsSb/AlGaAsSb nanoheterostructures (emission wavelength of λ ≈ 2.28 μm) operating in the whispering-gallery modes are fabricated and studied. The emission spectra and directivity patterns are studied for laser systems of two types, i.e., coupled disk lasers with a bridge between resonators and those without it. It is found that both types of these lasers generate collective modes with an intermodal difference twice as small as that for a single disk laser. It is suggested that this effect is caused by the propagation of radiation from one disk laser to the other.     

Tunability and bandwidth of microstrip filters fabricated on magnetized ferrites

The method of moments in the spectral domain is applied to the rigorous full-wave analysis of coupled line microstrip filters fabricated on magnetized ferrites. The results show that the center frequency of the filters can be tuned over a wide range by adjusting the magnitude of the bias magnetic field of the ferrite substrates. However, the filters bandwidth is reduced as the tuning frequency increases. This bandwidth reduction is explained in terms of the behavior of the resonant frequencies and quality factors of the resonators included in the filters.     

RF-MEMS谐振器和滤波器研究进展

介绍了基于梳状、梁式、圆盘三种结构的射频微机电系统( RF-MEMS)谐振器及滤波器,并对RF-MEMS谐振器及滤波器的结构与性能参数进行讨论;分析RF-MEMS谐振器及滤波器设计和制造中的有关问题及其处理方法;RF-MEMS谐振器及滤波器性能优异,能与其他器件实现片上集成,且与集成电路工艺兼容,在射频无线通信系统中的...     

Electrothermal noise analysis in frequency tuning of nanoresonators

Electrothermal tuning mechanisms for nanoelectromechanical resonators are demonstrated. Voltages induced by oscillation of Al/SiC nanoresonators around 10 MHz in a moderate magnetic field are measured using a room-temperature tabletop setup in moderate vacuum. The dynamic range as well as the resonance frequency of the resonator can be reversibly controlled by electrothermal tuning using DC voltage. This paper presents experimental results that demonstrates the effect of the resonance frequency, Q factor and dynamic range during the electrothermal tuning process. As the input DC power increases, Q factor decreases due to the decrease in the resonance frequency, and SNR decreases due to the reduced amplitude and increased noise. This can be explained by thermal relaxation of the resonator structure during the tuning process, and Johnson noise and eddy current effects associated with the magnetomotive transduction.     

High-Q channel-dropping filters using ring resonators with integrated SOAs

The filter response of single-ring resonators with integrated semiconductor optical amplifiers based on GaInAsP-InP is presented. The devices with free spectral ranges of 25 and 50 GHz have the form of a racetrack. An on-off ratio of 20 dB, a full-width at half-maximum of 12 and 24 pm, a finesse of 17, and a Q factor of 130,000 and 65,000, respectively, have been achieved. The tuning to a specific wavelength is performed by using integrated Pt-resistors.     

Dielectric ring resonators loaded in waveguide and on substrate

A rigorous mode matching technique is used to analyze the dielectric ring resonators loaded in a waveguide and on top of a substrate. Variation of several lowest order modes' resonant frequencies as a function of structure parameters is presented and is shown to be helpful for optimization of spurious mode separation. Two-dimensional electric and magnetic field line patterns and three-dimensional field intensity distributions of the ring resonators are plotted and provide information for mode excitation, coupling, and spurious mode suppression. Coupling between two dielectric ring resonators loaded in a metallic cavity are analyzed. The dielectric ring resonators are used to design a C-band elliptic function dual mode bandpass filter employing HE₁₁ modes. Experimental results are presented and show excellent agreement with the analytical solutions