Optimized Magneto-optical Isolator Designs Inspired by Seedlayer-Free Terbium Iron Garnets with Opposite Chirality

Dulal, Prabesh; Block, Andrew D.; Gage, Thomas; Haldren, Harold A.; Sung, Sang Yeob; Hutchings, D. C.; Stadler, Bethanie J. H.

doi:10.1021/acsphotonics.6b00313

Cited by 51 publications

(37 citation statements)

References 49 publications

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“…This top‐seedlayer process places the MO garnet in direct contact with the underlying Si waveguide, maximizing the coupling of light from the waveguide to the MO cladding, but it has only been applied to Ce:YIG. Recently rare‐earth garnets have been developed that crystallize on Si and quartz without a seed layer, including sputter‐deposited terbium iron garnet (TIG) and Bi‐doped TIG (Bi:TIG) …”

Section: Introductionmentioning

confidence: 99%

“…Growth of MO materials on the sidewall of the waveguide can enable a wider range of device designs, including isolators for transverse electric (TE) polarization. Integrated semiconductor lasers emit TE‐polarized light, and TE mode isolation using NRPS requires placement of the MO material on the sidewall of the waveguide to break left‐right symmetry . However, the NRPS‐based integrated optical isolators that have been experimentally demonstrated are made with the MO material on the top or bottom surface of the waveguide, which isolates only the transverse magnetic (TM) polarization .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Magneto‐Optical Bi:YIG Films with High Figure of Merit for Nonreciprocal Photonics

Fakhrul

Tazlaru

Beran

et al. 2019

Advanced Optical Materials

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lator devices is commonly a MO iron garnet material, in particular yttrium iron garnet (YIG, Y 3 Fe 5 O 12 ) with substituents such as Ce or Bi to increase the MO performance. [5][6][7][8][9][10][11][12][13][14][15] However, the integration of garnets on a Si (or other semiconductor) platform is challenging due to the incompatible lattice parameters and the thermal expansion mismatch between garnets and common semiconductor substrates. [6][7][8][9][10][11][12][13][14][15][16] Moreover, crystallization of the garnet phase usually requires a high thermal budget. Garnets formed on semiconductor substrates are polycrystalline and exhibit higher optical absorption than single crystal films. Furthermore, impurity phases such as YFeO 3 , Fe 2 O 3 , and Bi 2 O 3 can form during the crystallization process, [17] which contributes to optical loss. These factors result in inferior optical performance of polycrystalline MO garnet films compared to the bulk garnet material, and a lower figure of merit (FoM), defined as the ratio of the Faraday rotation to the absorption coefficient per length of the material.Considerable work has been done on growth of garnet films on semiconductors to enable demonstrations of isolators and modulators. [6][7][8][9][10][11][12][13][14][15][16] The first monolithically integrated optical isolator [6] used 80 nm thick Ce:YIG which was grown by pulsed laser deposition (PLD) on a pre-annealed 20 nm thick YIG seed layer to induce crystallization of the Ce:YIG. A simplified PLD process was introduced by Sun et al. [11] where the YIG seed layer was placed on top of the MO garnet and both layers were crystallized simultaneously by rapid thermal annealing (RTA). This top-seedlayer process places the MO garnet in direct contact with the underlying Si waveguide, maximizing the coupling of light from the waveguide to the MO cladding, but it has only been applied to Ce:YIG. Recently rare-earth garnets have been developed that crystallize on Si and quartz without a seed layer, including sputter-deposited terbium iron garnet (TIG) and Bi-doped TIG (Bi:TIG). [18,19] Growth of MO materials on the sidewall of the waveguide can enable a wider range of device designs, including isolators for transverse electric (TE) polarization. Integrated semiconductor lasers emit TE-polarized light, and TE mode isolation using NRPS requires placement of the MO material on the sidewall of the waveguide to break left-right symmetry. [18,20,21] However, the NRPS-based integrated optical isolators that have been experimentally demonstrated are made with the MO material on the top or bottom surface of the waveguide, which isolates only the transverse magnetic (TM) polarization. [6][7][8][11][12][13][14] It is therefore essential to establish deposition conditions that yield 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 d...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magneto‐Optical Bi:YIG Films with High Figure of Merit for Nonreciprocal Photonics

Fakhrul

Tazlaru

Beran

et al. 2019

Advanced Optical Materials

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“…On the other hand, by further improving the Ce:YIG and YIG figure of merit17 , the material loss can be improved. Reducing the YIG seed layer thickness or using a top seed layer can also lead to a much higher device FOM by increasing coupling of light from the waveguide into the Ce:YIG layer18,20 . Therefore a broadband monolithic isolator device with < 3 dB insertion loss is well within the reach of state-of-the art silicon photonic device technologies.In summary, we experimentally demonstrated monolithically integrated broadband optical isolators for both TE and TM polarizations on silicon and on SiN platforms for the first time.…”

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confidence: 99%

Monolithic integration of broadband optical isolators for polarization-diverse silicon photonics

Zhang

Wang

et al. 2019

Optica

165

108

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Integrated optical isolators have been a longstanding challenge for photonic integrated circuits (PIC). An ideal integrated optical isolator for PIC should be made by a monolithic process, have a small footprint, exhibit broadband and polarization-diverse operation, and be compatible with multiple materials platforms. Despite significant progress, the optical isolators reported so far do not meet all these requirements. In this article we present monolithically integrated broadband magneto-optical isolators on silicon and silicon nitride (SiN) platforms operating for both TE and TM modes with record high performances, fulfilling all the essential characteristics for PIC applications. In particular, we demonstrate fully-TE broadband isolators by depositing high quality magneto-optical garnet thin films on the sidewalls of Si and SiN waveguides, a critical result for applications in TE-polarized on-chip lasers and amplifiers. This work demonstrates monolithic integration of high performance optical isolators on chip for polarization-diverse silicon photonic systems, enabling new pathways to impart nonreciprocal photonic functionality to a variety of integrated photonic devices.

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“…The analysis may be applied to optimization of magnetooptic waveguides, fiber sensors of currents and magnetic fields, and to the evaluation of magnetic field effects in fiber gyroscopes [39][40][41][42][43]. The approach may be extended to nonreciprocal multilayer and graded circular cylindrical waveguides, nonreciprocal plasmonic waveguides, nonreciprocal cylindrical waveguides of (near) square cross sections [44][45][46][47][48], circular waveguide structures containing cylindrically anisotropic metamaterials [49], and waveguides displaying optical activity [50].…”

Section: Discussionmentioning

confidence: 99%

Magnetooptics in Cylindrical Structures

Višňovský

2018

Applied Sciences

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Understanding magnetooptics in cylindrical structures presents interest in the development of magnetic sensor and nonreciprocal devices compatible with optical fibers. The present work studies wave propagation in dielectric circular cylindrical structures characterized by magnetic permeability and electric permittivity tensors at axial magnetization. The Helmholtz equations deduced from the Maxwell equations in transverse circularly polarized representation provide electric and magnetic fields. With the restriction to terms linear in off-diagonal tensor elements, these can be expressed analytically. The results are applied to magnetooptic (MO) circular cylindrical waveguides with a step refractive index profile. The nonreciprocal propagation is illustrated on waveguides with an yttrium iron garnet (YIG) core and a lower refractive index cladding formed by gallium substituted yttrium iron garnet (GaYIG) at the optical communication wavelength. The propagation distance required for the isolator operation is about one hundred micrometers. The approach may be applied to other structures of cylindrical symmetry in the range from microwave to optical frequencies.

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Optimized Magneto-optical Isolator Designs Inspired by Seedlayer-Free Terbium Iron Garnets with Opposite Chirality

Cited by 51 publications

References 49 publications

Magneto‐Optical Bi:YIG Films with High Figure of Merit for Nonreciprocal Photonics

Magneto‐Optical Bi:YIG Films with High Figure of Merit for Nonreciprocal Photonics

Monolithic integration of broadband optical isolators for polarization-diverse silicon photonics

Magnetooptics in Cylindrical Structures

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