To improve the input-output coupling loss of a vertically coupled microring resonator filter, we fabricated microring resonators on an antiresonant reflecting optical waveguide (ARROW) with a large spot size and on the rectangular busline waveguide with a spot-size transformer. The spot size and the tapered structure were optimally designed from the viewpoint of spot-size matching to single-mode fibers and the reduction of radiation loss. Clear dropping responses were demonstrated for the ARROW-based microring resonator filters, and the coupling loss was successfully reduced by 22 dB.
© 2002 Optical Society of America
Tomoyuki Kato, Shuichi Suzuki, Yasuo Kokubun, and Sai Tak Chu, "Coupling-Loss Reduction of a Vertically Coupled Microring Resonator Filter by Spot-Size-Matched Busline Waveguides," Appl. Opt. 41, 4394-4399 (2002)