High extinction guided-wave optical polarization splitter

Conventional guided-wave optical polarization splitters exhibit poor polarization extinction characteristics because of the necessity of controlling waveguide parameters. In order to improve the characteristics, an electrical control scheme was investigated in an alternating Δβ directional coupler. Polarization-dependent electrooptic as well as polarization-independent plasma effects were employed to produce high extinction for two orthogonal polarizations independently. As a result, an extinction ratio as high as 32 dB was obtained with a fabricated GaAs-GaAlAs device. This is the highest value ever reported with a channel waveguide device     

Reversible and hierarchical composite gels with CdSe nanocrystals

To synthesize composite solid materials of metal salt and CdSe nanocrystals by a simple one-step method has been described. These solids can form stable gel in some organic solvent, such as benzene, cyclohexane and 1-butanol, especial in n-decane even below 0.1 wt/vol.%. Furthermore, these gels appear strong fluorescence which can be easily adjusted by the gel concentration. Temperature-dependent fluorescence spectra of composite gels suggested that the CdSe NCs aggregate together in gel state which would induce the energy transfer between nanocrystals and these aggregates could be reversibly disintegrated when gel was heated to form sol. TEM observations provided the further evidence of the energy transfer and suggested that the CdSe NCs were enchased regularly not only on the surface of self assembly of metal salt, but also embedded inside of self assembly in composite gel with small size nanocrystals. In contrast, in composite organogel with large nanocrystals they were only enchased on the edge of self assembly.     

Facilitating public awareness—the design of information distribution for communication in future workplaces

We present Emo System that extends e‐mail communication system in a workspace environment. In this system, the emotional information included in e‐mail message is extracted and shared in the public space, while reserving the private exchange of messages. As a result, people in the public space become aware of the ‘emotional’ information. This paper discusses how we extract and segment the information to share the emotional information. Copyright © 2008 John Wiley & Sons, Ltd.     

Single-transverse-mode 3.4-mW emission of oxide-confined 780-nmVCSELs

The authors have fabricated oxide-confined vertical-cavity surface-emitting lasers with metal apertures exhibiting a spatial mode filtering effect. Single-mode continuous-wave output is enhanced up to 3.4 mW by this effect for AlGaAs-based 780-nm vertical-cavity surface-emitting lasers with a 3.5-μm-diameter oxide aperture. From numerical calculations, the round-trip loss difference between zeroth- and first-order optical modes as a function of metal aperture size indicates that there is an optimum point; a 4-μm metal aperture size is suitable for higher order mode suppression of a 3.5-μm oxide aperture device     

Miniaturization of Bubbles by Shock Waves in Gas-Liquid Two-phase Flow in the Venturi Tube

Fine bubbles have been widely applied in many fields such as industry,medical engineering and agricultures.Therefore,many attentions have been paid to the study...