Heterogeneous microring and Mach-Zehnder modulators based on lithium niobate and chalcogenide glasses on silicon

Abstract

Thin films of lithium niobate are wafer bonded onto silicon substrates and rib-loaded with a chalcogenide glass, Ge(23)Sb(7)S(70), to demonstrate strongly confined single-mode submicron waveguides, microring modulators, and Mach-Zehnder modulators in the telecom C band. The 200 μm radii microring modulators present 1.2 dB/cm waveguide propagation loss, 1.2 × 10(5) quality factor, 0.4 GHz/V tuning rate, and 13 dB extinction ratio. The 6 mm long Mach-Zehnder modulators have a half-wave voltage-length product of 3.8 V.cm and an extinction ratio of 15 dB. The demonstrated work is a key step towards enabling wafer scale dense on-chip integration of high performance lithium niobate electro-optical devices on silicon for short reach optical interconnects and higher order advanced modulation schemes.

Monolithic ultra-high-Q lithium niobate microring resonator

“…The performances of these components have the potential to be dramatically improved as optical waveguides in bulk LN crystals are defined by ion-diffusion or proton-exchange methods which result in low index contrast and weak optical confinement. Integrated LN platform, featuring sub-wavelength scale light confinement and dense integration of optical and electrical components, has the potential to revolutionize optical communication and microwave photonics [1][2][3][4][5][6][7].The major road-block for practical applications of integrated LN photonics is the difficulty of fabricating devices that simultaneously achieve low optical propagation loss and high confinement. Recently developed thin-film LN-on-insulator technology makes this possible, and has resulted in the development of two complementary approaches to define nanoscale optical waveguides: hybrid and monolithic.…”

“…The performances of these components have the potential to be dramatically improved as optical waveguides in bulk LN crystals are defined by ion-diffusion or proton-exchange methods which result in low index contrast and weak optical confinement. Integrated LN platform, featuring sub-wavelength scale light confinement and dense integration of optical and electrical components, has the potential to revolutionize optical communication and microwave photonics [1][2][3][4][5][6][7].…”

Lithium niobate modulators on silicon beyond 20 GHz

“…2. This V L is > 26% smaller than previous reports [6,7], and is achieved here by optimization in the design and certain improvements in the processing flow. Ground-signal-ground (GSG) probes connected to a calibrated vector network analyzer (Agilent N5230C) are employed to characterize the S parameters of the radiofrequency (RF) travelling-wave coplanar waveguide electrodes, labelled S 11 & S 21 in Fig.…”

“…By integrating thin films of lithium niobate on silicon (LN-on-Si), compact optical modulators benefiting from the strong EO coefficient of LN, while maintaining potential integrability with silicon have been reported [6,7]. In this work, high-speed performance of these LNon-Si devices is investigated, showing their prospect for operation beyond 20 GHz for datacom applications.…”

“…DESIGN AND FABRICATION 400-nm-thick films of Y-cut LN are transferred to oxidized Si substrates, using ion implantation and wafer bonding methods [6,7]. To avoid etching LN, the thin films are subsequently rib-loaded by depositing and patterning a 500-nm-thick index-matching film to form compact (submicron) optical waveguides.…”