Tunable large free spectral range microring resonators in lithium niobate on insulator.

Microring resonators are critical photonic components used in filtering, sensing and nonlinear applications. To date, the development of high performance microring resonators in LNOI has been limited by the sidewall angle, roughness and etch depth of fabricated rib waveguides. We present large free spectral range microring resonators patterned via electron beam lithography in high-index contrast Z-cut LNOI.

Nanostructuring of LNOI for efficient edge coupling.

We present the design, fabrication and characterization of LNOI fiber-to-chip inverse tapers for efficient monolithic edge coupling. The etching characteristics of various LNOI crystal cuts are investigated for the realization of butt-coupling devices. We experimentally demonstrate that the crystal cut limits the performance of mode matching tapers studied in this work.

High coupling efficiency grating couplers on lithium niobate on insulator.

We demonstrate monolithically defined grating couplers in Z-cut lithium niobate on insulator for efficient vertical coupling between an optical fiber and a single mode waveguide. The grating couplers exhibit ∼ 44.6%/coupler and ∼ 19.

Ultra-low loss photonic circuits in lithium niobate on insulator.

Lithium niobate on insulator (LNOI) photonics promises to combine the excellent nonlinear properties of lithium niobate with the high complexity achievable by high contrast waveguides. However, to date, fabrication challenges have resulted in high-loss and sidewall-angled waveguides, limiting its applicability. We report LNOI single mode waveguides with ultra low propagation loss of 0.