Ion milled facet for direct coupling to optical waveguides

Paul M. Thomas; Michael Fanto; John Serafini; Jeffrey Steidle; Stefan Preble; Tsung-Ju Lu; Dirk Englund

doi:10.1117/12.2523433

13 May 2019 Ion milled facet for direct coupling to optical waveguides

Paul M. Thomas, Michael Fanto, John Serafini, Jeffrey Steidle, Stefan Preble, Tsung-Ju Lu, Dirk Englund

Proceedings Volume 10982, Micro- and Nanotechnology Sensors, Systems, and Applications XI; 109823H (2019) https://doi.org/10.1117/12.2523433
Event: SPIE Defense + Commercial Sensing, 2019, Baltimore, MD, United States

Abstract

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.

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Paul M. Thomas, Michael Fanto, John Serafini, Jeffrey Steidle, Stefan Preble, Tsung-Ju Lu, and Dirk Englund "Ion milled facet for direct coupling to optical waveguides", Proc. SPIE 10982, Micro- and Nanotechnology Sensors, Systems, and Applications XI, 109823H (13 May 2019); https://doi.org/10.1117/12.2523433

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