Takahiro Shiozawa

Live Electrooptic Imaging of

A novel method for real-time visual observation of traveling -band waves is described. Wave images and movies are acquired by a live electrooptic imaging (LEI) camera equipped with an optical source that emits signals modulated at a local oscillator (LO) frequency in the -band range. Waves propagating in a slab waveguide made of a semiconductor plate as well as in the air are successfully visualized. Especially in this paper, -band wave images for the aerial propagation in a variety of forms are presented: spherical and plane waves together with some fundamental wave phenomena such as reflection, interference, and diffraction at metal-air interfaces. The principle of 100-GHz optical LO signal generation at the optical wavelength of 780 nm as well as performance parameters such as the spatial resolution, bandwidth, and dynamic range of the camera are discussed. Further, some preliminary applications of the scheme are presented.

W

The optical cross-connect (OXC) system described in this paper increases the operation flexibility and reliability of the trunk-line optical networks used for data communication. It features an OXC node comprised of a photonic switching network and a conventional electric switching network that are connected hierarchically. The operation and management scheme proposed for this OXC system uses the concept of an optical path and an optical section. The OXC system allows hitless network reconfiguration by switching the photonic switches gradually and without interference effects. An experimental OXC network showed that a broken optical path is restored, by rerouting, within 50 ms. Experiments using a LiNbO/sub 3/ 8/spl times/8 photonic switch matrix also showed that the OXC system provides photonic hitless switching. These results confirm the feasibility of flexibly reconfigurable and fast-restorable OXC systems.

-Band Waves

A novel experimental approach has been proposed and demonstrated to visualize and characterize Bloch functions in two-dimensional microwave metamaterial structures. Internal waves in the structures have been visualized by the live electrooptic imaging technique and their wave vectors have been analytically characterized via complex Fourier transforms of experimentally generated complex phasor images. In addition, the two constituents of Bloch functions, i.e., plane wave envelope functions and periodic functions, have been dissected visually and characterized individually. Intriguing comprehensions of Bloch functions in metamaterials have been unveiled by the wave vector distributions and wave-dissected images thus obtained.

Optical cross-connect system incorporated with newly developed operation and management system

A 100-GHz-class live electrooptic imaging camera (LEI-camera), a novel microwave and millimeter-wave instrument, has been implemented for a scheme of W-band wave analyses. The first real-time visualization of W-band waves as phase-resolved images and phase-evolving movies has been successfully demonstrated, and the relevant images and/or movies obtained have been applied to the analyses of 100-GHz traveling waves. In conjunction with complementary numerical simulation approaches, studies have been conducted on a mode interaction between a ZnTe slab waveguide and a free space as well as on the loss tangent effect on W-band wave propagations. On the basis of the observed images and/or movies with live electrooptic imaging camera, some interesting analytical results have been obtained.

Experimental Visualizations and Wave Vector Characterizations of Bloch Functions in Microwave Metamaterial Structures

Recent progresses in the live electrooptic imaging (LEI) technique are reviewed with emphasis on its functionality of real-time visual accesses to traveling electric waves in the GHz range. Together with the principles, configurations, and procedures for the visual observation experiments by an LEI camera system, the following results are described as examples indicating the wide application ranges of the technique; Ku-band waves on arrayed planar antennas, waves on a Gb/s-class digital circuit, W-band waves traveling both in slab-waveguide modes and aerially, backward-traveling wave along composite right/left-handed transmission line, and, waves in monolithic microwave integrated circuit module case.

Image and/or Movie Analyses of 100-GHz Traveling Waves on the Basis of Real-Time Observation With a Live Electrooptic Imaging Camera

A unique approach has been proposed and demonstrated for experimental analyses of electromagnetic emission from planar antennas; their emission wavevectors are mapped in a wavenumber space. The proposed method consists of (a) the live electrooptic imaging technique visualizing their near fields in real time and (b) the two-dimensional Fourier transform of complex electrooptic images providing power spectra of emission. A proof-of-principle demonstration has been performed successfully for an 18-GHz wave emitted from a 2×2 patch array and its manipulation by dielectric loading.

Live Electrooptic Imaging Camera for Real-Time Visual Accesses to Electric Waves in GHz Range

Experimental radio wave analyses in both wavenumber and space domains have been proposed on the basis of the complex phasor image concept and applied to electrooptically visualized 100 GHz electric fields, leading to the following results: (a) several hidden waves are found in a wave image and identified clearly, (b) aerially propagating waves are accurately reproduced in images, (c) wavelength-dependent beam divergences are clearly visualized, and (d) power distributions among the waves are evaluated. In addition, the potential of high-quality three-dimensional radio wave imaging has been elucidated.

Wavevector mapping for antenna emission by Fourier transform of complex electrooptic images

A novel scheme involving experimental analyses and diagnoses is presented for monitoring radio-frequency (RF) and high-speed circuits. A live electrooptic imaging (LEI) camera is used in the scheme and it provides real-time images of the phase evolution of the RF electric field. Besides, it is demonstrated that essential properties of RF wave propagation are easily grasped from visual images; examples of LEI movies and images from which such essential properties can be identified are presented. The subjects of the LEI observations, analyses, and diagnoses are planar RF circuits and a Gbps-class emitter-coupled-logic circuit. In addition, the results of analyses and diagnoses in the space domain are discussed.

Phase-space analyses of electrooptically visualized 100 GHz waves employing complex phasor images

Experimental visualization of a wave packet traveling along a composite right/left-handed transmission line in its left-handed frequency band is successfully demonstrated. The demonstration is based on the RF wave visualization scheme of live electrooptic imaging technique in conjunction with composition of Fourier component video images. Propagation speed of the wave packet, i.e. group velocity was evaluated spatially on its propagation video. In addition, its frequency dependence, i.e. group velocity dispersion was characterized. Their comparison with those deduced from S-parameter measurement data was discussed.

RF wave visions for circuit analyses and diagnoses by live electrooptic imaging camera

A new scheme of electrooptic (EO) imaging, named detached EO imaging (DEI), has been proposed and demonstrated, where the finest imaging resolution for an electric field distribution over a planar circuit, which had been conventionally given by an EO sensor touching the circuit surface, has been provided by the EO sensor detached from the surface. An electromagnetic theory for the DEI scheme has been presented and proved by improved resolutions of detached EO images generated by numerical simulations and acquired by live electrooptic imaging experiments.