A novel design of waveguide adaptor for low loss mode conversion

Summary form only. We propose a novel method to design a tapered waveguide structure for low loss mode conversion. As the mode mismatch causes coupling loss and the loss depends on the tapered shape, it is important to design a tapering structure for various applications, such as low loss hetero-structure waveguide coupling or the spot-size-converter integrated laser diode. Recently, a novel concept for mode confinement index of a waveguide is proposed by using the overlap integration of two adjacent modes in tapered waveguide structure as a single step loss (SSL) in the unit of dB. It provides valuable information on the mode profile and has maximum optical confinement.