Ion milled facet for direct coupling to optical waveguides
Author(s)Lu, Tsung-Ju; Englund, Dirk R.
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Low loss coupling to optical waveguides is one of the on-going challenges with integrated photonics. Edge coupling of fibers or fiber arrays allows for in principle low loss coupling but strongly depends on the optical facet quality. We demonstrate an innovative strategy utilizing ion milling for polishing photonic integrated circuit edge facets for direct optical coupling to waveguides. Specifically, the authors created a 750 μm wide by 130 μm deep polished facet for coupling SM300 fiber to AlN waveguides on Al2O3 substrates; all capped with an index matched, but highly stressed, SiON cladding. Ion milling avoids the lateral shear forces that can delaminate a stressed film, resulting in scattering sites at the tapered edge coupler/facet interface. The authors demonstrate that a mechanical polish produced chipped facets that scattered the light away from the waveguide, thus requiring reprocessing of the chip. After ion milling, the authors coupled light into the waveguides and demonstrate critical coupling into AlN microring resonators between 390 and 395 nm.
DepartmentMassachusetts Institute of Technology. Research Laboratory of Electronics; Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Proceedings of SPIE - The International Society for Optical Engineering
SPIE-Intl Soc Optical Eng
Thomas, Paul M. et al. “Ion milled facet for direct coupling to optical waveguides.” Paper in the Proceedings of SPIE - The International Society for Optical Engineering, 10982, Micro- and Nanotechnology Sensors, Systems, and Applications XI, Baltimore, Md, 14-18 April 2019, SPIE: 109823H © 2019 The Author(s)
Final published version