Optical and magneto-optical behavior of Cerium Yttrium Iron Garnet thin films at wavelengths of 200–1770 nm (original) (raw)
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ACS Photonics, 2016
Simulations demonstrate that undoped yttrium iron garnet (YIG) seedlayers cause reduced Faraday rotation in silicon-oninsulator (SOI) waveguides with Ce-doped YIG claddings. Undoped seedlayers are required for the crystallization of the magneto-optical Ce:YIG claddings, but they diminish the interaction of the Ce:YIG with the guided modes. Therefore new magneto-optical garnets, terbium iron garnet (TIG) and bismuth-doped TIG (Bi:TIG), are introduced that can be integrated directly on Si and quartz substrates without seedlayers. The Faraday rotations of TIG and Bi:TIG films at 1550nm were measured to be +500 and-500°/cm, respectively. Simulations show that these new garnets have the potential to significantly mitigate the negative impact of the seedlayers under Ce:YIG claddings. The successful growth of TIG and Bi:TIG on low-index fused quartz inspired novel garnet-core waveguide isolator designs, simulated using finite difference time domain (FDTD) methods. These designs use alternating segments of positive and negative Faraday rotation for push-pull quasi phase matching in order to overcome birefringence in waveguides with rectangular cross-sections.
Advanced Optical Materials, 2021
Films of polycrystalline terbium iron garnet (TbIG), cerium substituted TbIG (CeTbIG) and bismuth substituted TbIG (BiTbIG) were grown on Si substrates by pulsed laser deposition. The films grow under tensile strain due to thermal mismatch with the Si substrate, resulting in a dominant magnetoelastic anisotropy which, combined with shape anisotropy, leads to in-plane magnetization. TbIG has a compensation temperature of 253 K which is reduced by substitution of Ce and Bi. The Faraday rotation at 1550 nm of the TbIG, Ce0.36TbIG and Bi0.03TbIG films were 5400 600 o /cm, 4500 100 o /cm and 6200 300 o /cm respectively while Ce0.36TbIG and Bi0.03TbIG exhibited lower optical absorption than TbIG, attributed to a reduction in Fe 2+ and Tb 4+ absorption pathways. The high Faraday rotation of the films, and in particular the high magnetooptical figure of merit of the Bi0.03TbIG of 720 o dB-1 at 1550 nm, make these polycrystalline films valuable for applications in integrated photonics.
Strong enhancement of the Faraday rotation in Ce and Bi comodified epitaxial iron garnet thin films
Applied Physics Letters, 2009
Ce and Bi comodified iron garnet ͑Ce 2.2 Bi 0.8 Fe 5 O 12 ͒ thin films for magneto-optic applications were epitaxially grown on a ͑111͒-oriented Gd 3 Ga 5 O 12 substrate by pulsed laser deposition. We found that epitaxial film quality could be achieved under a low-pressure Ar atmosphere. Surprisingly, our 1 m thick epitaxial films showed a record Faraday rotation as high as 0.55 deg/ m, a value strongly dependent on the concentration of Bi 3+ ions.
Fabrication of Integrated Magneto-Optic Isolator
MRS Proceedings, 2004
ABSTRACTIn optical applications, especially in optical communications, protecting light sources from harmful reflected energy is very important. With magneto-optic isolators, these light sources can be protected to extend their lifetimes and performance by blocking back-reflected light. The active element in these optical isolators is a magneto-optical garnet. However, garnet is difficult to integrate with semiconductors due to the high thermal budget usually required to obtain the garnet crystal structure. For example, current isolator garnets cannot be integrated monolithically into a photonic integrated circuit due to the growth process, liquid phase epitaxy, which requires growth temperatures of >900 °C and also garnet substrates. In this work, magneto-optical garnets were grown monolithically by low-temperature reactive RF sputtering, followed by an ultra-short (<15 sec) anneal. The refractive indices of the resulting garnets were measured using Fourier transform infrared...
Study of magneto-optical characteristics of cerium incorporated yttrium iron garnet films
Materials Research Bulletin, 2018
In the current study, yttrium iron garnet films incorporated with cerium with the general formula of Ce x Y 3x Fe 5 O 12 and values of (x = 0, 0.1, 0.3, 0.5, 0.7) were prepared through sol-gel method using spin coating technique and heating treatment on quartz substrates. Prepared samples were studied to check physical characteristics. X-ray diffraction analysis (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and vibrating sample magnetometer (VSM) were applied to study the impact of Ce impurities on the structural characteristic, surface morphology of films and magnetic properties, respectively. Faraday rotation values of samples were measured at the wavelength of 632 nm. The image of the atomic force microscope (AFM) of the prepared samples shows that the films have a continuous and smooth surface.
Magneto‐Optical Bi:YIG Films with High Figure of Merit for Nonreciprocal Photonics
Advanced Optical Materials, 2019
Thin film magneto‐optical (MO) materials are enablers for integrated nonreciprocal photonic devices such as isolators and circulators. Films of polycrystalline bismuth‐substituted yttrium iron garnet (Bi:YIG) have been grown on silicon substrates and waveguide devices, in which an yttrium iron garnet (YIG) seedlayer is placed either above or below the active Bi:YIG layer to promote crystallization. The films exhibit a high MO figure of merit of up to 769° dB−1 at 1550 nm wavelength. Growth of single phase Bi:YIG on the sidewalls of waveguides is demonstrated, which can be used in nonreciprocal transverse electric (TE)‐mode devices.
Magneto-optic waveguide isolators based on laser annealed (Bi, Ga) YIG films
1985
To overcome the effects of linear birefringence which limits the Faraday rotation achievable in magneto-optic thin film waveguides, a novel geometrical pattern of Faraday effect reversals has been designed. This pattern of P/2 segments followed by a P/4 segment where P is the birefringent period, has been built permanently into a (Bi,Ga)YIG film, with composition close to the compensation point, by laser annealing. This film provides nonreciprocal rotation of *45' for light of wavelength 1.45 pm with an extinction ratio of 500 to 1, corresponding to 27 db of isolation.
Optimized magneto-optical isolator design based on cerium-substituted yttrium iron garnet fiber
Optical and Quantum Electronics, 2021
Numerical analysis of a magneto-optical (MO) fiber based on cerium-substituted yttrium iron garnet (Ce:YIG) is presented to design a kind of MO isolator. The unique MO properties of garnets are used to produce the non-reciprocal (NR) effect. The aim of this work consists of optimizing the properties of the fiber by reducing modal birefringence ( ∆n ) using the NR TE-TM mode conversion. Therefore, the performance of the proposed structure is investigated to study the MO behavior under the influence of magnetic gyration ( g ). The optimized mode conversion isolation ratio of 93.88% is attained. Next, Faraday rotation (FR) and ∆n have been calculated, the results reveal a proportional relation between FR and g . Another relationship between ∆n and g is demonstrated, where the two limits values are 0.0022 × 10 –5 and 0.7 × 10 –5 for g = 0.0037 and g = 0.032, respectively. The enhanced MO properties could improve the efficiency of the designed MO isolator.
Robust perpendicular magnetic anisotropy in Ce substituted yttrium iron garnet epitaxial thin films
Journal of Applied Physics
Cerium substituted yttrium iron garnet (Ce:YIG) epitaxial thin films are prepared on a gadolinium gallium garnet (GGG) substrate with pulsed laser deposition. It is observed that the films grown on a GGG(111) substrate exhibit perpendicular magnetic anisotropy (PMA) as compared to films grown on a GGG(100) substrate. The developed PMA is confirmed from a magneto-optical Kerr effect, bulk magnetization, and ferromagnetic resonance measurements. Furthermore, the magnetic bubble domains are observed in the films exhibiting PMA. The observations are explained in terms of the growth direction of Ce:YIG films and the interplay of various magnetic anisotropy terms. The observed PMA is found to be tunable with the thickness of the film, and a remarkable temperature stability of the PMA is observed in all the studied films of Ce:YIG deposited on a GGG(111) substrate.