We propose a compact multi-channel 90 optical deflection device for short-distance optical interconnection. The device consists of stacked bent multimode optical waveguides having reflecting mirrors with bending angles of 90. The structure of the bent multimode optical waveguide with a bending angle of 90 was designed by ray-tracing simulations. The simulated insertion loss for each channel of the device was 0.5 dB. We also propose a simple fabrication process using a pair of multi-channel linear optical waveguides with symmetrical 45 mirrors. An 8-channel 90 optical deflection device was fabricated using polymer materials and basic operation was confirmed. Our device has good potential for use as a high-density optical interconnection device.

This paper proposes the overlapped block relaxation Newton method for greatly reducing the number of iterations needed for simulating large scale nonlinear circuits. The circuit is partitioned into subcircuits, i.e., overlapped blocks consisting of core nodes and overlapped nodes. The core nodes form the core circuit for each overlapped block and the overlapped nodes form the overlapped circuit. The Newton-Raphson method is applied to all overlapped blocks independently and the approximation vector for relaxation is determined by node voltages of core nodes. An overlapped circuit is considered to be the representative circuit of the outside circuit for the core circuit. Therefore, the accuracy of the approximation vector for relaxation may be improved and the number of relaxation steps may be greatly reduced. Core nodes are determined automatically by reflecting the circuit structure, then the overlapping level is determined automatically. We show that this method has good performance for simulating large scale circuits, and that it is faster than the nonlinear direct method which is used in standard circuit simulators.