planar lightwave circuit; air trenches; ring resonator; Mach-Zehnder interferometer; total internal reflection; guided waves; integrated optics


We discuss the design of a compact ring resonator (RR) and Mach-Zehnder interferometer (MZI) in a low-refractive-index-contrast waveguide material system through the use of air trenches. A narrow air trench at the intersection of one input and two output waveguides can function as a high-efficiency splitter, while wider air trenches operate as waveguide bends. We first discuss the design of individual splitters and bends and then show how they can be used to realize a compact MZI and RR. The RR has a footprint of only 70 X 100 um, and its optical efficiency at the drop wavelengths is 86%. The free spectral range and full width at half maximum are 7.2 and 0.5 nm, while the Q factor is >3,000. The MZI occupies only 165 X 130 um, and its calculated optical efficiency is 90%.

Original Publication Citation

Seunghyun Kim, Jianhua Jiang, and Gregory P. Nordin, Design of compact polymer Mach-Zender interferometer and ring resonator with air trench structures, Opt. Eng. 45, 5462 (26)

Document Type

Peer-Reviewed Article

Publication Date


Permanent URL


SPIE -- Society of Photo-Optical Instrumentation Engineers




Ira A. Fulton College of Engineering and Technology


Electrical and Computer Engineering