Bending loss reduction in silica-based waveguides by using lateral offsets

The excess loss that occurs in waveguide bends can be minimized by offsetting the connecting waveguides so as to reduce the transition loss at the junctions. Such bends were investigated in detail by employing the beam propagation method (BPM) and it was found that they can be optimized with respect to overall loss. In the addition, the S-shaped waveguides and directional couplers with offset junctions were fabricated based on silica-based planar lightwave circuits (PLC) on silicon substrates. The measured insertion losses of these S-shaped waveguides and directional couplers, which are in good agreement with the calculated results, are the lowest thus far reported.<
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