A TM010 cavity power combiner is presented, which achieves direct interface to microstrip lines via magnetic field coupling. A prototype is fabricated and its S-matrix measured. From the S-parameters we calculate that it shows less than 0.85 dB insertion loss over 250 MHz bandwidth at X-band. The return power to the input ports is less than -15 dB over this bandwidth. We verify the insertion loss estimation using S-matrix, by measuring transmission S-parameter of a concatenated 2-port divider-combiner network. Similarly analyzed is the case of performance of power combiner when one of the input fails. We find that we can achieve graceful degradation provided we ensure some particular reflection phase at the degraded port.

This paper presents an analysis of the cavity length modulation of a Z-cut quartz etalon equipped with a weight for Laser Diode (LD) wavelength lockers. The electro-optic effect, piezoelectric effect and photo-elastic effect are considered, and the mechanical movement of the etalon with a weight is analyzed by using a mechanical circuit. Approximate equations that clearly explain the mechanical force, mechanical resonance frequency, and Q factor of the mechanical resonance are obtained. The mechanism for improving the modulation efficiency by placing a weight is clarified. We also compare the analysis with experimental results, and show that most of the experimental values are in accord with the calculated values.

This paper presents a wavelength lock system using a Z-cut quartz etalon supported at the middle point. The Z-cut quartz etalon possesses the cavity length modulation and the low temperature coefficient. We propose a Z-cut quartz etalon supported at the middle point in order to improve the modulation index and response time. The mechanism of the center supported Z-cut quartz etalon is described. We also show that the etalon possesses a high modulation index, a high Q factor, and a rapid response time in experimental results. A self-tuning dither oscillator realized by using quartz etalon is also described.

The boundary integral equation (BIE) on interior walls with surface impedance conditions is implemented to the iterative physical optics method and how to treat the singularities involved in the BIE of an impedance cavity is described. Singular integrals over a rectangular region can be represented by simple elementary functions.

Photonic crystals have seen major advances in the past few years in the optical range. The association of in-plane waveguiding and two-dimensional photonic crystals (PCs) in thin-slab or waveguide structures leads to good 3D confinement with easy fabrication. Such structures, much easier to fabricate than 3D PCs open many exciting opportunities in optoelectronic devices and integrated optics. We present experiments on a variety of structures and devices, as well as modelling tools, which show that 2D PCs etched through waveguides supported by substrates are a viable route to high-performance PC-based photonic integrated circuits (PICs). In particular, they exhibit low out-of-plane diffraction losses. Low-loss waveguides, high finesse microcavities, and their mutual coupling are demonstrated. PACS: 42.70 QS, 42.55 Sa, 42.82 m, 42.50-p.

Photonic crystals have seen major advances in the past few years in the optical range. The association of in-plane waveguiding and two-dimensional photonic crystals (PCs) in thin-slab or waveguide structures leads to good 3D confinement with easy fabrication. Such structures, much easier to fabricate than 3D PCs open many exciting opportunities in optoelectronic devices and integrated optics. We present experiments on a variety of structures and devices, as well as modelling tools, which show that 2D PCs etched through waveguides supported by substrates are a viable route to high-performance PC-based photonic integrated circuits (PICs). In particular, they exhibit low out-of-plane diffraction losses. Low-loss waveguides, high finesse microcavities, and their mutual coupling are demonstrated. PACS: 42.70 QS, 42.55 Sa, 42.82 m, 42.50-p.

The Finite-Difference Time-Domain (FDTD) method has been applied to study the scattering characteristics of Fabry-Perot cavities with infinite planar periodic surfaces. Periodic Boundary Conditions (PBC) are used to reduce the analysis to one unit periodic volume. Both dielectric and metallic losses are included in the algorithm using a frequency dependent formalism. This technique is used to study the frequency response of plane parallel Fabry-Perot cavities with square aperture metal mesh mirrors. These cavities are assumed to be illuminated by a normally incident plane wave. After a detailed description of the algorithm, we show theoretically the separate effects of dielectric and metal losses on the transmission coefficient of such cavities. We compare also simulation results to measurements, in the 60 GHz band, of resonant frequencies and Q factors of cavities with various mesh parameters.

The use of selective oxidation to fabricate vertical-cavity surface-emitting lasers is described. The nativeoxide impacts the device design in two ways, the first being in the introduction of an intracavity dielectric aperture that laterally confines the mode, and the second in the formation of high contrast dielectric Bragg reflectors to shorten the effective cavity length. To date the more important has been the indexconfinement, with record low threshold currents, threshold voltages, and power conversion efficiencies being reported from several groups. However, future designs will likely also benefit from the reduced diffraction loss for a small mode size that is possible with high contrast native oxide/semiconductor mirrors. We describe some of the most important design issues in obtaining ultralow threshold operation.

A hybrid analysis of the electromagnetic scattering by an open cavity containing an interior obstacle when it is illuminated by an external source is presented so that it is valid for high frequencies. This hybrid approach breaks down the problem into three basic parts which can be analyzed separately, via methods best suited for each part, and these separate solutions are then combined systematically via generalized recipricity relations to obtain the total solution. The three separate analyses deal with the scattering by the open end being illuminated, the wave propagation within the cavity, and the scattering by the interior obstacle. The propagation region analysis is based on the use of the generalized ray expansion that employs a new elliptic ray tube basis set which makes this expansion far more efficient in that it requires significantly fewer number of these than is possible with conventional ray tubes. Numerical results illustrating the utility of this hybrid approach are presented.

A rigorous radar cross section (RCS) analysis of a two-dimensional parallel-plate waveguide cavity with three-layer material loading is carried out for the E- and H-polarized planc wave incidence using the Wiener-Hopf technique. Introducing the Fourier transform for the scattered field and applying boundary conditions in the transform domain, the problem is formulated in terms of the simultaneous Wiener-Hopf equations satisfied by the unknown spectral functions. The Wiener-Hopf equations are solved via the factorization and decomposition procedure together with rigorous asymptotics, leading to the efficient approximate solution. The scattered field in the real space is evaluated by taking the inverse Fourier transform and applying the saddle point method. Representative numerical examples on the RCS are given for various physical parameters. It is shown that the three-layer lossy material loading inside the cavity results in significant RCS reduction over broad frequency range.

The plane wave diffraction by a two-dimensional parallel-plate waveguide cavity with partial material loading is rigorously analyzed for both the E and the H polarization using the Wiener-Hopf technique. Introducing the Fourier transform for the scattered field and applying boundary conditions in the transform domain, the problem is formulated in terms of the simultaneous Wiener-Hopf equations satisfied by the unknown spectral functions. The Wiener-Hopf equations are solved exactly via the factorization and decomposition procedure leading to the formal solution, which involves branch-cut integrals with unknown integrands as well as infinite series with unknown coefficients. Applying rigorous asymptotics with the aid of the edge condition, the approximate solution to the Wiener-Hopf equations is derived in the form suitable for numerical computations. The scattered field inside and outside the cavity is evaluated by taking the inverse Fourier transform together with the use of the saddle point method. Numerical examples of the radar cross section are presented for various physical parameters, and the far field backscattering characteristics of the cavity are discussed in detail. Some comparisons with a high-frequency technique are also given to validate the present method.

The diffraction of a plane electromagnetic wave by a parallel-plate waveguide cavity with a thick planar termination is rigorously analyzed for both the E and the H polarization using the Wiener-Hopf technique. Introducing the Fourier transform for the unknown scattered field and applying boundary conditions in the transform domain, the problem is formulated in terms of the simultaneous Wiener-Hopf equations, which are solved exactly in a formal sense via the factorization and decomposition procedure. Since the formal solution involves an infinite number of unknowns and branch-cut integrals with unknown integrands, approximation procedures based on rigorous asymptotics are further presented to yield the approximate solution convenient for numerical computations. The scattered field inside and outside the cavity is evaluated by taking the inverse Fourier transform and applying the saddle point method. Representative numerical examples of the monostatic and bistatic radar cross sections are presented for various physical parameters, and the scattering characteristics of the cavity are discussed in detail.