High-Q lithium niobate microdisk resonators on a chip for efficient electro-optic modulation

Abstract

Lithium niobate (LN) microdisk resonators on a LN-silica-LN chip were fabricated using only conventional semiconductor fabrication processes. The quality factor of the LN resonator with a 39.6-μm radius and a 0.5-μm thickness is up to 1.19 × 10(6), which doubles the record of the quality factor 4.84 × 10(5) of LN resonators produced by microfabrication methods allowing batch production. Electro-optic modulation with an effective resonance-frequency tuning rate of 3.0 GHz/V was demonstrated in the fabricated LN microdisk resonator.

Domain Patterning in Ion-Sliced LiNbO3 Films by Atomic Force Microscopy

“…Some encouraging results were obtained in studies of LNOI-based optical elements, such as photonic crystals [4,5], high-Q microresonators [6][7][8], ridge-waveguides [9,10], proton-exchanged waveguides [11][12][13] and modulators [14], hybrid lightwave circuits LNOI-SOI [15], etc. These results indicate that LNOI is an appropriate platform for integrated optics.…”

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].…”

“…The monolithic approach relies on direct etching of LN to achieve high optical confinement in the active region, but has suffered from a relatively high propagation loss. While freestanding LN microdisk resonators have achieved optical quality factors (Q) of ∼ 10 6 [5,6], integrated microring resonators typically feature Q ∼ 10 5 with waveguide propagation loss on the order of 3 dB/cm [7]. Since LN is perceived as a difficult-to-etch material, it is commonly accepted that low-loss propagation in a monolithic waveguide is not possible, and that therefore it is not the most promising path forward.…”

Design of nanobeam photonic crystal resonators for a silicon-on-lithium-niobate platform

“…Unfortunately, it is far less amenable to microfabrication techniques than silicon, and processes such as dry etching high-quality wavelength scale optical structures are difficult and non-standard. Nonetheless, ion sliced thin films of LN have been developed in the last few years [5][6][7][8][9] to facilitate among other things nanophotonic fabrication, and more recently, high quality chip-scale optical resonators have been demonstrated in these materials [10][11][12][13][14]. In a recent work on mid-infrared modulators, thin-film silicon was wafer-bonded to LN [15].…”