Using tightly focused femtosecond laser pulses, we produce an optical waveguide and devices in transparent materials. This technique has the potential to generate not only channel waveguides, but also three‐dimensional optical devices. In this paper, an optical splitter and U‐grooves, which are used for fiber alignment, are simultaneously fabricated in a fused silica glass using near‐IR femtosecond laser pulses. The fiber‐aligned optical splitter has a low insertion loss, less than 4 dB, including an intrinsic splitting loss of 3 dB and excess loss due to the passive alignment of a single‐mode fiber. Finally, we present an output field pattern, demonstrating that the splitting ratio of the optical splitter becomes approximately 1:1.

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In this paper, for the first time, we propose a novel rerouting approach which actively packs existing connections of different bandwidth granularities. Basically different from previously proposed active rerouting that blindly attempts to reroute many existing lightpaths, our algorithm at first estimates the potential resource gain of each existing connection and then reroutes only a small number of candidate connections that may give the largest gains. Therefore, it can efficiently reduce the rerouting costs, i.e., the required overheads and computations, while maximizing the amount of resources that can be conserved for future requests.

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