title: Fabrication of free-standing lithium niobate nanowaveguides down to 50 nm in width.
abstract: Nonlinear optical nanoscale waveguides are a compact and powerful platform for efficient wavelength conversion. The free-standing waveguide geometry opens a range of applications in microscopy for local delivery of light, where in situ wavelength conversion helps to overcome various wavelength-dependent issues, such as biological tissue damage. In this paper, we present an original patterning method for high-precision fabrication of free-standing nanoscale waveguides based on lithium niobate, a material with a strong second-order nonlinearity and a broad transparency window covering the visible and mid-infrared wavelength ranges. The fabrication process combines electron-beam lithography with ion-beam enhanced etching and produces nanowaveguides with lengths from 5 to 50 μm, widths from 50 to 1000 nm and heights from 50 to 500 nm, each with a precision of few nanometers. The fabricated nanowaveguides are tested in an optical characterization experiment showing efficient second-harmonic generation.
authors.affiliation: Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Geiss
authors.forename: Anton
authors.initials: A
authors.lastname: Sergeyev
authors.forename: Holger
authors.initials: H
authors.lastname: Hartung
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Solntsev
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Sukhorukov
authors.forename: Rachel
authors.initials: R
authors.lastname: Grange
authors.forename: Frank
authors.initials: F
authors.lastname: Schrempel
authors.forename: Ernst-Bernhard
authors.initials: EB
authors.lastname: Kley
authors.forename: Andreas
authors.initials: A
authors.lastname: Tünnermann
authors.forename: Thomas
authors.initials: T
authors.lastname: Pertsch