Photonic guiding structures in lithium niobate crystals produced by energetic ion beams

Abstract

A range of ion beam techniques have been used to fabricate a variety of photonic guiding structures in the well-known lithium niobate (LiNbO3 or LN) crystals that are of great importance in integrated photonics/optics. This paper reviews the up-to-date research progress of ion-beam-processed LiNbO3 photonic structures and reports on their fabrication, characterization, and applications. Ion beams are being used with this material in a wide range of techniques, as exemplified by the following examples. Ion beam milling/etching can remove the selected surface regions of LiNbO3 crystals via the sputtering effects. Ion implantation and swift ion irradiation can form optical waveguide structures by modifying the surface refractive indices of the LiNbO3 wafers. Crystal ion slicing has been used to obtain bulk-quality LiNbO3 single-crystalline thin films or membranes by exfoliating the implanted layer from the original substrate. Focused ion beams can either generate small structures of micron or submicron dimensions, to realize photonic bandgap crystals in LiNbO3, or directly write surface waveguides or other guiding devices in the crystal. Ion beam-enhanced etching has been extensively applied for micro- or nanostructuring of LiNbO3 surfaces. Methods developed to fabricate a range of photonic guiding structures in LiNbO3 are introduced. Modifications of LiNbO3 through the use of various energetic ion beams, including changes in refractive index and properties related to the photonic guiding structures as well as to the materials (i.e., electro-optic, nonlinear optic, luminescent, and photorefractive features), are overviewed in detail. The application of these LiNbO3 photonic guiding structures in both micro- and nanophotonics are briefly summarized.

Optical Waveguides Fabricated by Ion Implantation/Irradiation: A Review Optical Waveguides Fabricated by Ion Implantation/Irradiation: A Review

“…and Er 3+ -doped telluride glass (Berneschi et al, 2007b), achieving unprecedented control over the refractive index changes of the substrate. Moreover, irradiation with swift heavy ions have been also used to produce waveguides in a wide number of materials, like LiNbO 3 (Olivares et al, 2005b(Olivares et al, , 2007bChen, 2009b;Dong et al, 2011a), KGW (García-Navarro et al, 2006), KLTN (Ilan et al, 2006), BGO , Nd:YAG (Ren et al, 2010a(Ren et al, , 2011a, Nd:GdCOB (Ren et al, 2011b), a-SiO 2 (Manzano et al, 2010), c-SiO 2 (Manzano-Santamaría et al, 2012) and chalcogenide glasses , allowing a fast fabrication of high-quality waveguides. In this section we briefly review the fabrication and properties of ion implanted waveguides in various materials, emphasizing the most recent results.…”

“…Later, in a follow-up review paper, Chen and co-workers summarized the progresses between 1994 and 2006. Moreover, there have been some focused reviews, presenting the progresses on the 2D waveguide production in insulating materials by ion implantation (Chen, 2008), waveguides fabricated on lithium niobate (LiNbO 3 ) by the irradiation with swift heavy ions (SHI) (Olivares et al, 2007c) and the production of photonic guiding structures on LiNbO 3 by energetic ion beams (Chen, 2009b). However, despite these precedents, there have been in recent years a large number of achievements in these areas that make necessary and updated review summarizing them.…”

Structural and Electronic Parameters of Complex Niobates and Tantalates

“…In oxides the M 5+ ions are coordinated by four or six oxygen atoms. To illustrate these coordinations, crystal structure of LaNbO 4 , in space group I2/a, and LiNbO 3 , in space group R3c, are shown in Figures 1 and 2, respectively [12,13]. Many niobate and tantalate crystals show high ferroelectric, piezoelectric and nonlinear optical properties [8,9].…”

“…Many niobate and tantalate crystals show high ferroelectric, piezoelectric and nonlinear optical properties [8,9]. In technological applications, niobate crystals are used in the fabrication of nonlinear optical and integrated optical devices, acousto-electronic devices, photocatalysts and nanotechnology [3][4][5][6][7][14][15][16][17][18] surface reduction of M 5+ -oxide crystals to lower the valence states of M cations can be achieved by ion or electron bombardment widely used in modern electronic technology for surface treatments [4,[19][20][21]. Chemical state of the crystal surface can be modified by the formation of the solid solutions that results in strong variation of chemical reactivity and physical properties [1,2,4,7,14,17,[20][21][22][23].…”

“…Complex oxide compounds containing niobium and tantalum play a very important role in many areas of microand nanoelectronics, nanochemistry and materials science [1][2][3][4][5][6][7]. Because of the wide structural geometries with strong distortion of the MO 6 (M = Nb, Ta) octahedra and high electronic polarizability of the M-O bonds, niobates and tantalates show versatile electronic and optical properties and pronounced ability for the formation of noncentrosymmetrical crystal structures [8][9][10][11].…”