Optical and magneto-optical behavior of Cerium Yttrium Iron Garnet thin films at wavelengths of 200-1770 nm.

Mehmet C Onbasli,Martin Zahradník,Lukáš Beran,Miroslav Kučera,Caroline A Ross,Jan Mistrík,Gerald F Dionne,Martin Veis,Roman Antoš

doi:10.1038/srep23640

Abstract

Magneto-optical cerium-substituted yttrium iron garnet (Ce:YIG) thin films display Faraday and Kerr rotation (rotation of light polarisation upon transmission and reflection, respectively) as well as a nonreciprocal phase shift due to their non-zero off-diagonal permittivity tensor elements, and also possess low optical absorption in the near-infrared. These properties make Ce:YIG useful in providing nonreciprocal light propagation in integrated photonic circuits, which is essential for accomplishing energy-efficient photonic computation and data transport architectures. In this study, 80 nm-thick Ce:YIG films were grown on Gadolinium Gallium Garnet substrates with (100), (110) and (111) orientations using pulsed laser deposition. The films had bulk-like structural and magnetic quality. Faraday and Kerr spectroscopies along with spectroscopic ellipsometry were used to deduce the complete permittivity tensor of the films in the ultraviolet, visible and near-infrared spectral region, and the magneto-optical figure of merit as a function of wavelength was determined. The samples showed the highest IR Faraday rotation reported for thin films of Ce:YIG, which indicates the importance of this material in development of nonreciprocal photonic devices.

Highlights

A major roadblock for completing a fully-integrated optical signal processor has been the processing of MO garnet films which is necessary to integrate optical isolators onto photonic circuits based on Si or other substrates
We present the complete optical characterization of thin CeYIG films cerium-substituted yttrium iron garnet (Ce):YIG (Ce1Y2Fe5O12) films grown on gadolinium gallium garnet (Gd3Ga5O12, GGG) substrates over visible and near infrared bands
Despite the interest in using garnet films for nonreciprocal photonic devices, to the best of our knowledge, there is no comprehensive report of the optical properties and magneto-optical figure of merit of Ce:YIG as a function of wavelength

Summary

Introduction

A major roadblock for completing a fully-integrated optical signal processor has been the processing of MO garnet films which is necessary to integrate optical isolators onto photonic circuits based on Si or other substrates. Despite the interest in using garnet films for nonreciprocal photonic devices, to the best of our knowledge, there is no comprehensive report of the optical properties and magneto-optical figure of merit of Ce:YIG as a function of wavelength. The knowledge of these variables, which are captured in the diagonal and off-diagonal elements of the permittivity tensor, is necessary to design and optimize devices such as integrated magneto-optical isolators. This tensor form can be used for a theoretical description of both Faraday and polar Kerr magneto-optical effects since the magnetization is oriented in the same direction

Methods

Results

Conclusion