Development and design of a dielectric optical waveguide with reduced bend loss

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K06402
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Electron device/Electronic equipment
• Research Institution: Hosei University
• Principal Investigator: Yamauchi Junji 法政大学, 理工学部, 教授 (50174579)
• Co-Investigator(Kenkyū-buntansha): 柴山 純 法政大学, 理工学部, 教授 (40318605)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 光回路 / 屈曲導波路 / 電磁波解析

Outline of Final Research Achievements

The imaginary-distance procedure with an enhanced amplification factor is applied to the Yee-mesh-based implicit beam-propagation method in the cylindrical co-ordinate system. The developed technique is adopted to study the effect of core location in a buried Si-wire waveguide with various aspect ratios. Reduced bend loss is achieved when the air-cladding interface is placed at the position where the field amplitude decays to 5% of its peak. In comparison with the results obtained from the transformed index method in the rectangular co-ordinate system, we find the transformed technique based on an exponential function is superior to that obtained from a linear function.
We finally investigate the effect of the sidewall roughness on the propagation behavior. It is found that the bend loss becomes largest when the correlation length is around 100 nm, and that the polarization crosstalk remains rather small, compared with the crosstalk generated with a tilted sidewall.

Free Research Field

通信ネットワーク工学

Academic Significance and Societal Importance of the Research Achievements

屈曲光導波路は、あらゆる光伝送回路に使用されている。屈曲損を低減できると、回路のコンパクト化が達成できる利点がある。本研究では、主に通信波長帯で屈曲損低減効果を検討したが、可視光帯でも同じ理論が適用でき、応用範囲が広い。
市販のソフトウェアで屈曲導波路を解析するには、直交座標系で直線的に屈折率を変換する手法が多用されているが、本研究では、指数関数で近似する手法がより精度の高いことを明らかにした。市販のソフトウェアの計算精度を簡便に上げることができる。