Refractive index engineering through swift heavy ion irradiation of LiNbO3 crystal towards improved light guidance

Chen Chen,Lei Wang,Zhiguang Wang,Feng Chen,Yang Tan,Qingming Lu,Lilong Pang

doi:10.1038/s41598-017-11358-y

Chen Chen, Lei Wang + Show 5 more

Open Access

https://doi.org/10.1038/s41598-017-11358-y

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Abstract

Swift heavy ion irradiation has been widely used to modify refractive indices of optical materials for waveguide fabrication. In this work, we propose refractive index engineering by swift heavy ion (Ar) irradiation via electronic energy deposition to construct waveguides of diverse geometries in LiNbO3 crystal. The feasibility to modulate the refractive index of LiNbO3 crystal at variable depths through electronic energy depositions of argon ions at different energies has been experimentally explored. The surface and cladding-like optical waveguides with thicknesses of ~13, ~36 and ~23 μm have been produced by using swift Ar ion irradiation at single energy of ~120, ~240, and double energy of (120 + 240) MeV, respectively. The fabricated waveguides are capable of effective waveguiding in single and multiple modes at 1064 nm, which enables efficient guided-wave second harmonic generation at room temperature. This work paves the way to produce waveguides with diverse geometries in dielectric crystals through electronic damage of multiple swift heavy ion irradiation.

Highlights

Energetic ion beam processing techniques, such as ion implantation, swift heavy ion irradiation, focused ion beam irradiation, have been intensively applied to modify the physical, chemical, electrical and optical properties of numerous materials[1,2,3,4,5,6,7,8]
Interactions between incident argon (Ar12+) ions with energies ranging from 50 to 300 MeV and the target LiNbO3 crystal were predicted using the code of Stopping and Range of Ions in Matter 2013 (SRIM 2013)[32], which is based on Monte Carlo approach
We have explored the feasibility of modulating the refractive indices of x-cut LiNbO3 crystal in variable depths by electronic energy depositions of irradiated argon ions

Summary

Introduction

Energetic ion beam processing techniques, such as ion implantation, swift heavy ion irradiation, focused ion beam irradiation, have been intensively applied to modify the physical, chemical, electrical and optical properties of numerous materials[1,2,3,4,5,6,7,8]. It has been demonstrated that the incident ions could induce a refractive index change of the target crystal to produce optical waveguide structure[7, 8]. Through the implantation or irradiation of ions with diverse species, fluences, and energies, waveguide structures have been fabricated in a large number of optical materials with desirable geometries and refractive index distributions[7]. The refractive index modification is induced through the structural damage caused by elastic nuclear collisions between incident ions and target atoms (correlated to nuclear stopping power Sn), which happens mainly at the end of ion’s range. Photonic devices with various refractive index distributions are expected to emerge through the superposition of electronic damage in multiple swift heavy ion irradiations

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