We have fabricated and characterized straight single-line-defect two-dimensional photonic-crystal waveguides on GaAs films with lengths of 1, 4, and 10 mm. By optimizing key processes for smooth top and bottom waveguide-surface, as well as fine patterning process of the air holes, extremely low propagation loss was achieved. The optimization includes wet etching process of a sacrificial AlGaAs clad layer and oxygen plasma process for complete resist removal. AFM measurement resulted that the surface roughness is less than 1 nm at the top surface of the line-defect waveguide. From the transmittance spectra for different-length samples, the propagation loss is estimated as small as 0.76/spl plusmn/0.5 dB/mm. Besides the loss for the straight waveguide, the loss per bend for the 60/spl deg/ bend waveguide was estimated as 0.3 dB/bent with the bandwidth of broader than 40 nm. The present results are promising for key passive elements such as photonic-crystal symmetric Mach-Zehnder switches needed in future optical communication applications.

We have experimentally demonstrated two- dimensional (2-D) photonic crystal (PC) waveguides (WGs) such as straight, bent, Y-branch, directional coupler (DC), and quantum dots (QDs)-based nonlinear optical (NLO) WGs using a GaAs air-bridge membrane with triangular-lattice line-defect WGs. These WGs are necessary for a 2-D PC-based symmetric Mach-Zehnder (PC-SMZ) type ultrafast all-optical switch. Experimental results on the clear observation of the optical interference at the Y-junction DC, nonlinearity-induced phase shift at the NLO waveguide, and transmission spectra in the total PC-SMZ WG configuration will be addressed, as well as measured results on each WG element.

We presented some developments to ensure the absolute safety of equipment. We can make the equipment compact, simple, reliable, and easy to handle without any stress. In Toyota, we have become able to provide the "Safe Partner" equipment to factories by applying the technologies reported in this paper. To make the factories a more attractive place to work, we are advancing the development of this equipment as a means to help workers in future factories. Considering the restrictive climate facing domestic production, it has become more important for us to grasp firmly the needs of the factories based on the concept of "source analysis and resolution", and promote such improvements.