Nanophotonic lithium niobate electro-optic modulators

Abstract

Since the emergence of optical fiber communications, lithium niobate (LN) has been the material of choice for electro-optic modulators, featuring high data bandwidth and excellent signal fidelity. Conventional LN modulators however are bulky, expensive and power hungry, and cannot meet the growing demand in modern optical data links. Chip-scale, highly integrated, LN modulators could offer solutions to this problem, yet the fabrication of low-loss devices in LN thin films has been challenging. Here we overcome this hurdle and demonstrate monolithically integrated LN electro-optic modulators that are significantly smaller and more efficient than traditional bulk LN devices, while preserving LN's excellent material properties. Our compact LN electro-optic platform consists of low-loss nanoscale LN waveguides, micro-ring resonators and miniaturized Mach-Zehnder interferometers, fabricated by directly shaping LN thin films into sub-wavelength structures. The efficient confinement of both optical and microwave fields at the nanoscale dramatically improves the device performances featuring a half-wave electro-optic modulation efficiency of 1.8 V∙cm while operating at data rates up to 40 Gbps. Our monolithic LN nanophotonic platform enables dense integration of high-performance active components, opening new avenues for future high-speed, low power and cost-effective communication networks.

High‐Q 2D Lithium Niobate Photonic Crystal Slab Nanoresonators

“…It shows a clear cubic dependence on the pump power, an intrinsic signature of third‐harmonic generation. To the best of our knowledge, this is the first time to observe third‐harmonic generation in on‐chip LN nanophotonic devices . The observed THG could contribute from cascaded SHG, direct THG from the third‐order optical nonlinearity, or a combination of these two processes.…”

“…We have demonstrated 2D LN PhC slab nanoresonators with optical Q up to 3.51 × 10 5 that is about three orders of magnitude higher than other 2D LN PhC nanoresonators reported to date . The high optical Q together with tight optical mode confinement results in intriguing nonlinear optical interactions, allowing us to observe both second‐ and third‐harmonic generation . Moreover, the devices exhibit specific polarization of the cavity modes, which enabled us to probe the intriguing anisotropy of nonlinear optical phenomena.…”

“…Lithium niobate (LN), known as “silicon of photonics,” exhibits outstanding electro‐optic, nonlinear optical, acousto‐optic, piezoelectric, photorefractive, pyroelectric, and photoconductive properties, promising for broad applications . The great application potential has attracted significant attention recently to develop LN photonic devices on chip‐scale platforms . However, realizing high‐quality 2D LN PhC structures remains significant challenge, which becomes the major obstacle hindering the exploration of optical phenomena in the nanoscopic scale that would potentially result in intriguing device characteristics and novel functionalities inaccessible by conventional means.…”

A Theoretical Study on Rib‐Type Photonic Wires Based on LiNbO3 Thin Film on Insulator

“…The LNOI structure has been pioneered by the groups of Osgood [4] and Günter [5] on smaller substrates. To date, many LNOI PW devices have been demonstrated, such as (CMOS-compatible) electro-optic modulator, [10][11][12][13][14][15][16][17][18][19] (electrooptically tunable) micro-ring or micro-disk resonator, [7,[19][20][21][22][23][24][25][26][27][28][29] LNOI heterogeneous photonic device, [19] grating coupler, [30,31] photonic crystal, [7,[32][33][34] transverse-electric/magnetic (TE/TM)pass polarizer, [35] quantum optics device, [36] as well as some nonlinear devices based on periodically poled LNOI (PPLNOI) PWs. in diameter) LNOI thin-film is commercially available.…”

Photorefractive Properties of Molybdenum and Hafnium Co-Doped LiNbO3 Crystals

“…Lithium niobate (LiNbO 3 , or LN) crystal is one of the most prominent materials for applications in many practical fields, such as optical modulators [1], holographic storage [2], waveguides [3,4], resonators [5], and integrated optics devices, resulting from its superior and diverse physical performance [6,7]. In recent decades, crystal growth, defect structures, photorefractive properties, phase-matching, and theoretical simulations have been studied in depth and substantial research progress has been reported for LN crystals [7][8][9][10].…”