High-quality lithium niobate photonic crystal nanocavities

Abstract

Lithium niobate (LN) exhibits unique material characteristics that have found many important applications. Scaling LN devices down to a nanoscopic scale can dramatically enhance light-matter interaction that would enable nonlinear and quantum photonic functionalities beyond the reach of conventional means.However, developing LN-based nanophotonic devices turns out to be nontrivial. Although significant efforts have been devoted in recent years, LN photonic crystal structures developed to date exhibit fairly low quality. Here we demonstrate LN photonic crystal nanobeam resonators with optical Q as high as 10 5 , more than two orders of magnitude higher than other LN nanocavities reported to date. The high optical quality together with tight mode confinement leads to extremely strong nonlinear photorefractive effect, with a resonance tuning rate of ∼0.64 GHz/aJ, or equivalently ∼84 MHz/photon, three orders of magnitude greater than other LN resonators. In particular, we observed intriguing quenching of photorefraction that has never been reported before. The devices also exhibit strong optomechanical coupling with gigahertz nanomechanical mode with a significant f · Q product of 1.47 × 10 12 Hz. The demonstration of high-Q LN photonic crystal nanoresonators paves a crucial step towards LN nanophotonics that could integrate the outstanding material properties with versatile nanoscale device engineering for diverse intriguing functionalities. * These authors contributed equally to this work. † Electronic address: qiang.lin@rochester.edu 1 arXiv:1706.08904v2 [physics.optics]

Status and Potential of Lithium Niobate on Insulator (LNOI) for Photonic Integrated Circuits

“…The extinction ratio of this filter was 12.5 dB and the cavity had a Q factor of 156. Recently, a photonic crystal nanobeam resonators with optical Q as high as 10 5 has been demonstrated in LNOI . This is an outstanding achievement, as the Q is two orders of magnitude higher compared to previous results.…”

High‐Q 2D Lithium Niobate Photonic Crystal Slab Nanoresonators

“…Figure d–e show the simulated optical mode field profiles of the fundamental ( and ) and second‐order () TE‐like cavity modes, which exhibit radiation‐limited optical Qs of 1.5 × 10 6 , 5 × 10 5 , and 3 × 10 5 , respectively, with effective mode volumes of 2.43, 3.06, and 4.63. In particular, the nearly vertical device sidewalls here significantly decrease the polarization hybridization, in contrast to the 1D photonic crystal nanobeams demonstrated recently . For example, the fundamental cavity mode shown in Figure d exhibits 62.5% of its energy in the z ‐polarization lying in the device plane, almost zero in the x ‐direction, and about 37.5% in the y ‐direction.…”

“…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.…”

Coupling a Superconducting Quantum Circuit to a Phononic Crystal Defect Cavity

“…The cooperativity C ∼ 4 is already sufficient for efficient conversion of microwave photons to highly localized microwave phonons, which can in turn be upconverted efficiently to optical photons [17]-a promising route for microwave-to-optical conversion [12,14,31,32]. We note that our approach of direct coupling to a phononic Since the anharmonicity χ is negative, the resonator redshifts as its occupation n r increases; here, we plot the absolute value of the shift for clarity.…”