We propose a gap-less optical interconnection between BGA package and board for practical on-board, chip-to-chip optical interconnection. The optical interconnect consists of polymer optical waveguides, an integral mirror on the PWB (printed wiring board), an optical via hole through package, and a connection structure and method requiring no alignment process. Optical waveguide, mirror, waveguide extensions and alignment studs were fabricated on the PWB as horizontal optical interconnect. Coaxial structured optical vias with core and cladding were formed through the package and with precise holes for alignment. Two packages were attached onto the PWB using standard BGA technology utilizing passive optical alignment. The optical characteristics and 10 Gbit/s open-eye diagram were measured. A completely gap-less three dimensional optical interconnect between package-PWB-package was demonstrated.

The aperture feed with an air cavity in a LTCC (Low Temperature Co-fired Ceramics) post-wall waveguide with dielectric constant εr more than 5 is proposed for bandwidth enhancement in the millimeter wave band. A rectangular cavity is adopted because only one mask pattern of a rectangular can be used for each layer of LTCC for reducing the number of the design parameters and the cost. The fabrication limitation such as the spacing between the post edge and the aperture edge reduces the bandwidth. The feeding structures are designed at 61.25 GHz for a range of εr from 2.0 to 9.0. In the case of εr = 7.0, the bandwidth for reflection below -15 dB with the air cavity is 4.25 times that without the air cavity in simulation, and 3.10 times in measurement.

The design of multi-branch optical waveguides having 3 or more output ports is not so easy as that of 2-output branches because some innovative geometry is required to realize equal power splitting. All previous studies take the same approach in which they first introduce innovative geometries and then adjust the structural parameters for equal splitting. On the other hand, we propose quite a different method where distribution of refractive index is calculated from an ideal field distribution which is synthesized artificially. The method is extended to design 3-D 4-branch waveguides. It is exemplified that 4-branch waveguides with low-loss and equal splitting can be realized by the proposed method.

This paper presents the formulation for the evaluation of external coupling in the alternating-phase feed single-layer slotted waveguide array antenna with baffles by using the Spectrum of Two-Dimensional Solutions (S2DS) method. A one-dimensional slot array is extracted from the array by assuming the periodicity in transversal direction and introducing the perfect electric conductors in the external region. The uniform excitation over the finite array is synthesized iteratively to demonstrate the fast and accurate results by S2DS. A unit design model with the baffles is introduced to determine the initial parameters of the slot pair which accelerate the iteration. Experiment at 25.3 GHz demonstrates good uniformity of the aperture field distribution as well as the effects of the baffles. The directivity is 32.7 dB which corresponds to the aperture efficiency 90.5% and the reflection is below -15.0 dB over 1.3 GHz.

In this paper, we suggest a method of analyzing the post-wall waveguide (PWW) or the substrate integrated waveguide (SIW) by applying the analytical technique of the H-plane waveguide discontinuities based on the planar circuit approach. The analytical procedure consists of the derivation of the mode impedance matrices for regular-shaped circuits and the short-circuiting operation on fictitious ports arranged at the peripheries of the metallic posts. First, a straight section of the PWW is treated as an example and the analytical method for the calculation of the S-parameters is described in detail. Then the attenuation and phase constants of the PWW are computed with the aid of the Thru-Reflect Line (TRL) calibration technique. Next, the analytical method is applied to the design of two types of right-angled corners. The analysis and the design results are verified using an em-simulator (HFSS).

In this paper, we design and manufacture a flanged double ridged waveguide with a tapered section as a sample holder for measuring the electromagnetic shielding effectiveness (SE) of planar material in broadband frequency ranges up to 10 GHz. The proposed technique overcomes the limitations of the conventional ASTM D4935 test method at high frequencies. The simulation results for the designed sample holders agree well with the fabricated ones in consideration of the design specification of S11 < -20 dB within the frequency range of 1-10 GHz. To verify the proposed measurement apparatus, the measured SE data of the commercial shielding materials from 1 to 10 GHz were indirectly compared with those obtained from the ASTM D4935 from 30 MHz to 1 GHz. We observed that the SE data obtained by using both experimental techniques agree with each other.

In situ observation of electrochemical activity and time dependent characteristics of cytochrome c (cyt c) was carried out in 0.01 M phosphate buffered saline (PBS, pH 7.4) containing 20 µM cyt c solutions at bare indium-tin-oxide (ITO) electrodes by using a cyclic voltammetry (CV) and a slab optical waveguide (SOWG) spectroscopy. The bare ITO electrodes could retain the electrochemical activity of cyt c in the PBS solutions, indicating the great advantage of using ITO electrodes against other electrode materials, such as gold (Au). The CV curves and simultaneously observed the time-resolved SOWG absorption spectra in the consecutive cycles implied that the cyt c molecules could retain its own electrochemical function for a long time.

A transducer with a wide step from a post-wall waveguide to a hollow waveguide width is proposed which is tolerant against the aperture offset. The modes in the step width of about 1.50 wavelengths are stable for the aperture offset and the fields are not so perturbed while in the conventional stepped structure with step width of about 1.00 wavelength, the higher evanescent mode of TE30 is excessively enhanced by the aperture offset. The operation of the transducer with the wider step is robust for the fabrication errors in the millimeter wave band. It is also suggested that the anti-symmetrical TE20 mode which is excited only by non-zero offset or the misalignment of the aperture exists in both structures and can not be the dominant factor for the improvement. The transducers are designed and fabricated at 61.25 GHz using PTFE substrate with glass fiber of εr=2.17. The bandwidth for the reflection lower than -15 dB is almost unchanged (6.30-6.60 GHz) for the offset from -0.2 mm to 0.2 mm, while it is degraded in the conventional stepped structure, from 7.65 GHz for no offset to 3.30-5.70 GHz for the same range of the offset.

A new structure of a waveguide-type left-handed transmission line is proposed. It is composed of two rectangular waveguides with many stubs. One waveguide is put on another waveguide symmetrically. When one mode with odd electric field distribution is excited, the stubs work as open stubs and the mode propagates with very small loss. Guided regions of the left-handed mode and a right-handed mode are discussed using an approximate equivalent circuit. Tuning the structure parameters, the band gap between the two regions can be removed, and the wave propagates continuously from the left-handed frequency regions to the right-handed frequency region. The transmission line is applied to a leaky waveguide. It is confirmed experimentally that the beam angle of the radiation wave changes from the backward to the forward directions.

A novel amplification mechanism of traveling TM wave on an electron beam within a waveguide structure is proposed. Under boundary constraint of the waveguide, a hybrid coupling of longitudinal plasma wave and transverse guided one occurs to result in traveling instability. The instability refers to a backward traveling amplification. The new amplification in the waveguide due to the interactive coupling between the space charge mode and the waveguide one is firstly pointed out. The analysis is extended to the relativistic energy range to get a large gain. The features and properties are discussed for a wide frequency range as well as a high gain-bandwidth product.

Lightweight single-layer slotted waveguide array antennas are fabricated using plastic materials with metal-plating. A plastic material that has good heat-radiation properties is investigated. Three types of antennas are fabricated by milling, using ABS resin, heat-radiating plastic, and aluminum alloy. In measurements, all three types of antennas are confirmed to have almost the same VSWR and gain in the 25 GHz frequency band.

We have successfully demonstrated a GaInAs/InP multiple quantum well (MQW)-based wavelength switch composed of the straight arrayed waveguide with linearly varying refractive index distribution by changing the refractive index using thermo-optic effect. Since optical path length differences between waveguides in the array were achieved through refractive index differences that were controlled by SiO2 mask design in selective metal-organic vapor phase epitaxy (MOVPE), wavelength demultiplexing, and the output port switching in each wavelength of light by the refractive index change in the array waveguides through the thermo-optic effect were achieved. We have obtained the wavelength switching and the change of transmission spectra in each output ports.

We propose a polymeric waveguide optical switch using a novel drive mechanism. The switch uses a flexible polymeric waveguide film where trenches are formed at cross-points of the waveguides. Light passes through the trench while it is closed. When the trench opens, light path changes by total internal reflection between the air gap and the polymeric waveguide. Therefore, we can control light paths by changing the trench state between closed and open one. In order to realize this, a rotating arm is inserted near the trench. As rotational force transfers to the trench through the arm and the film, the trench switches from closed to open state and vice versa. We investigated this rotary drive mechanism by three-dimensional (3D) structural analysis, designed the optical switch, and experimentally demonstrated the switching operation.

The center-feed in a single-layer slotted waveguide array[1]-[3] is one of the key components in polarization division duplex (PDD) wireless systems. Two center-feed arrays with orthogonal polarization and boresight beams are orthogonally arranged side-by-side for transmission and reception, simultaneously. Each antenna has extremely high XPD (almost 50 dB in measurement) and a very high isolation (over 80 dB in measurement) between two arrays is observed provided the symmetry of slot arrangement is preserved [4]. Unfortunately, the area blocked by the center feed causes high sidelobe levels. This paper proposes the ridged cross-junction multiple-way power divider for realizing blockage reduction and symmetrical slot arrangement at the same time.

A novel dual mode bandpass filter (BPF) with improved spurious response is presented in this letter. To obtain low insertion loss, the coupling structure using the dual mode resonator and the feeding scheme using coplanar-waveguide (CPW) are constructed on the two sides of a dielectric substrate. A defected ground structure (DGS) is designed on the ground plane of the CPW to achieve the goal of spurious suppression of the filter. The filter has been investigated numerically and experimentally. Measured results show a good agreement with the simulated analysis.

Integration of light sources on a Si chip is one of milestone to establish new paradigm of LSI systems, so-called "silicon photonics." In recent years remarkable progress has been made in the Si wire waveguide technologies for optical interconnection on a Si chip. In this paper, several Er embedded materials based on silicon are surveyed from the standpoint of application to the light emission and amplification devices for silicon photonics. We have concentrated to investigate an erbium silicate (Er2SiO5) as a light source medium for silicon photonics. To mention the particular features, this material has a layered structure with 0.86-nm period and a large amount of Er (25at%) as its constituent. The single crystalline nature gives several remarkable properties for the application to silicon photonics. We also discuss our recent studies of Er2SiO5 and a possibility of the shorter waveguide amplifier.

LSI on-chip optical interconnections are discussed from the viewpoint of a comparison between optical and electrical interconnections. Based on a practical prediction of our optical device development, optical interconnects will have an advantage over electrical interconnects within a chip that has an interconnect length less than about 10 mm at the hp32-22 nm technology node. Fundamental optical devices and components used in interconnections have also been introduced that are small enough to be placed on top of a Si LSI and that can be fabricated using methods compatible with CMOS processes. A SiON waveguide showed a low propagation loss around 0.3 dB/cm at a wavelength of 850 nm, and excellent branching characteristics were achieved for MMI (multimode interference) branch structures. A Si nano-photodiode showed highly enhanced speed and efficiency with a surface plasmon antenna. By combining our Si nano-photonic devices with the advanced TIA-less optical clock distribution circuits, clock distribution above 10 GHz can be achieved with a small footprint on an LSI chip.

Transmission line metamaterials on coplanar waveguide with series-capacitive and shunt-inductive distributed loading in periodical intervals are characterized using our developed fullwave self-calibrated method of moments. Firstly, the two effective per-unit-length transmission parameters, i.e., complex propagation constant and characteristic impedance, are numerically extracted. The results provide a straightforward insight into the forward- and backward-wave propagation characteristics in several distinctive bands, including the left- and right-handed stopbands and passbands. In particular, it is demonstrated that in the whole left-handed passband, the propagation constant has purely negative phase constant while the characteristic impedance has only positive real quantity. Next, varied left- and right-handed passbands are studied in terms of lower/higher cut-off frequencies based on ideal equivalent circuit model and practical distributed CPW elements, respectively. Of particular importance, the left-handed and right-handed passbands find to be able to be directly connected with a seamless bandgap under the condition that normalized inductance and capacitance of loaded CPW inductive and capacitive elements become exactly the same with each other. Finally, the 9-cell metamaterial circuits on CPW with actual 50 Ω feed lines are designed and implemented for experimental validation on the derived per-unit-length parameters.

A compact arrayed-waveguide grating with small-bend waveguides incorporating air trenches and high mesa structures has been proposed. An 8-channel, 100-GHz-spacing silica arrayed-waveguide grating was fabricated, and its size was reduced dramatically to 1/4 of that of a conventional device.

This letter describes a millimeter wave slot array antenna using a rectangular waveguide and a ferrite. The radiation direction of the leaky wave from the slot array can be scanned by applying a dc bias magnetic field parallel to the ferrite. The radiation pattern of a prototype antenna has been measured at 40 GHz. The main beam direction changes from 10 to 3 degree by the bias magnetic field of 0.73 T.