High-Gyrotropy Seedlayer-Free Ce:TbIG for Monolithic Laser-Matched SOI Optical Isolators

Karthik Srinivasan; Cui Zhang; Prabesh Dulal; Cosmin Radu; Thomas E. Gage; David C. Hutchings; Bethanie J.H. Stadler

doi:10.1021/acsphotonics.9b00707

High-Gyrotropy Seedlayer-Free Ce:TbIG for Monolithic Laser-Matched SOI Optical Isolators

Karthik Srinivasan, Cui Zhang, Prabesh Dulal, Cosmin Radu, Thomas E. Gage, David C. Hutchings, Bethanie J.H. Stadler

Electrical and Computer Engineering

Research output: Contribution to journal › Article › peer-review

20 Scopus citations

Abstract

Monolithic optical isolators that provide modal (transverse electric, TE) and dimensional (500 nm core) matching to on-chip lasers have been realized with "one step" seedlayer-free garnets. To date, seedlayer-free garnet claddings have required thinner (<340 nm) silicon-on-insulator (SOI) cores because mode-cladding interactions were too weak for laser-matched cores. However, laser matching is important because tapers and mode converters between the laser and the isolator can cause detrimental reflections prior to isolation. This paper reports the use of cerium-doped terbium iron garnet (Ce:TbIG) in a quasi-phase matched nonreciprocal mode conversion (NRMC) isolator that operates on both TE and TM modes without an external field. A key innovation presented here is a repeatable process for foundry-friendly sputter deposition of Ce:TbIG, which enables this high Faraday rotation material (-3200°/cm) to be synthesized in any isolator design that would benefit from one-step lithographical manufacturing. A proof-of-feasibility 500 nm SOI NRMC device is demonstrated with seedlayer-free Ce:TbIG that achieves an isolation ratio of 11 dB. With an optimal length, this NRMC design can provide greater than 30 dB isolation.

Original language	English (US)
Pages (from-to)	2455-2461
Number of pages	7
Journal	ACS Photonics
Volume	6
Issue number	10
DOIs	https://doi.org/10.1021/acsphotonics.9b00707
State	Published - Oct 16 2019

Bibliographical note

Funding Information:
This research was sponsored as a World Materials Network project by the U.S. National Science Foundation (DMR-1210818) and the U.K. Engineering and Physical Sciences Research Council (EP/J018708/1) and also supported by the China Scholarship Council. Parts of this work were carried out in the Characterization Facility and the Minnesota Nano Center, University of Minnesota, which receives partial support from the NSF through the MRSEC and the National Nano Coordinated Infrastructure Network (NNCI Award Number 1542202) programs, respectively. The authors acknowledge the valuable support of waveguide patterning by the technical staff of the James Watt Nanofabrication Centre. Useful discussions with Dr. Barry Holmes are acknowledged by the authors.

Publisher Copyright:
© 2019 American Chemical Society.

Keywords

Faraday rotation
cerium-doped terbium iron garnet
isolators
magnet-free isolators
magneto-optical garnets
non-reciprocal mode conversion
silicon photonics

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title = "High-Gyrotropy Seedlayer-Free Ce:TbIG for Monolithic Laser-Matched SOI Optical Isolators",

abstract = "Monolithic optical isolators that provide modal (transverse electric, TE) and dimensional (500 nm core) matching to on-chip lasers have been realized with {"}one step{"} seedlayer-free garnets. To date, seedlayer-free garnet claddings have required thinner (<340 nm) silicon-on-insulator (SOI) cores because mode-cladding interactions were too weak for laser-matched cores. However, laser matching is important because tapers and mode converters between the laser and the isolator can cause detrimental reflections prior to isolation. This paper reports the use of cerium-doped terbium iron garnet (Ce:TbIG) in a quasi-phase matched nonreciprocal mode conversion (NRMC) isolator that operates on both TE and TM modes without an external field. A key innovation presented here is a repeatable process for foundry-friendly sputter deposition of Ce:TbIG, which enables this high Faraday rotation material (-3200°/cm) to be synthesized in any isolator design that would benefit from one-step lithographical manufacturing. A proof-of-feasibility 500 nm SOI NRMC device is demonstrated with seedlayer-free Ce:TbIG that achieves an isolation ratio of 11 dB. With an optimal length, this NRMC design can provide greater than 30 dB isolation.",

keywords = "Faraday rotation, cerium-doped terbium iron garnet, isolators, magnet-free isolators, magneto-optical garnets, non-reciprocal mode conversion, silicon photonics",

author = "Karthik Srinivasan and Cui Zhang and Prabesh Dulal and Cosmin Radu and Gage, {Thomas E.} and Hutchings, {David C.} and Stadler, {Bethanie J.H.}",

note = "Funding Information: This research was sponsored as a World Materials Network project by the U.S. National Science Foundation (DMR-1210818) and the U.K. Engineering and Physical Sciences Research Council (EP/J018708/1) and also supported by the China Scholarship Council. Parts of this work were carried out in the Characterization Facility and the Minnesota Nano Center, University of Minnesota, which receives partial support from the NSF through the MRSEC and the National Nano Coordinated Infrastructure Network (NNCI Award Number 1542202) programs, respectively. The authors acknowledge the valuable support of waveguide patterning by the technical staff of the James Watt Nanofabrication Centre. Useful discussions with Dr. Barry Holmes are acknowledged by the authors. Publisher Copyright: {\textcopyright} 2019 American Chemical Society.",

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AU - Srinivasan, Karthik

AU - Zhang, Cui

AU - Dulal, Prabesh

AU - Radu, Cosmin

AU - Gage, Thomas E.

AU - Hutchings, David C.

AU - Stadler, Bethanie J.H.

N1 - Funding Information: This research was sponsored as a World Materials Network project by the U.S. National Science Foundation (DMR-1210818) and the U.K. Engineering and Physical Sciences Research Council (EP/J018708/1) and also supported by the China Scholarship Council. Parts of this work were carried out in the Characterization Facility and the Minnesota Nano Center, University of Minnesota, which receives partial support from the NSF through the MRSEC and the National Nano Coordinated Infrastructure Network (NNCI Award Number 1542202) programs, respectively. The authors acknowledge the valuable support of waveguide patterning by the technical staff of the James Watt Nanofabrication Centre. Useful discussions with Dr. Barry Holmes are acknowledged by the authors. Publisher Copyright: © 2019 American Chemical Society.

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N2 - Monolithic optical isolators that provide modal (transverse electric, TE) and dimensional (500 nm core) matching to on-chip lasers have been realized with "one step" seedlayer-free garnets. To date, seedlayer-free garnet claddings have required thinner (<340 nm) silicon-on-insulator (SOI) cores because mode-cladding interactions were too weak for laser-matched cores. However, laser matching is important because tapers and mode converters between the laser and the isolator can cause detrimental reflections prior to isolation. This paper reports the use of cerium-doped terbium iron garnet (Ce:TbIG) in a quasi-phase matched nonreciprocal mode conversion (NRMC) isolator that operates on both TE and TM modes without an external field. A key innovation presented here is a repeatable process for foundry-friendly sputter deposition of Ce:TbIG, which enables this high Faraday rotation material (-3200°/cm) to be synthesized in any isolator design that would benefit from one-step lithographical manufacturing. A proof-of-feasibility 500 nm SOI NRMC device is demonstrated with seedlayer-free Ce:TbIG that achieves an isolation ratio of 11 dB. With an optimal length, this NRMC design can provide greater than 30 dB isolation.

AB - Monolithic optical isolators that provide modal (transverse electric, TE) and dimensional (500 nm core) matching to on-chip lasers have been realized with "one step" seedlayer-free garnets. To date, seedlayer-free garnet claddings have required thinner (<340 nm) silicon-on-insulator (SOI) cores because mode-cladding interactions were too weak for laser-matched cores. However, laser matching is important because tapers and mode converters between the laser and the isolator can cause detrimental reflections prior to isolation. This paper reports the use of cerium-doped terbium iron garnet (Ce:TbIG) in a quasi-phase matched nonreciprocal mode conversion (NRMC) isolator that operates on both TE and TM modes without an external field. A key innovation presented here is a repeatable process for foundry-friendly sputter deposition of Ce:TbIG, which enables this high Faraday rotation material (-3200°/cm) to be synthesized in any isolator design that would benefit from one-step lithographical manufacturing. A proof-of-feasibility 500 nm SOI NRMC device is demonstrated with seedlayer-free Ce:TbIG that achieves an isolation ratio of 11 dB. With an optimal length, this NRMC design can provide greater than 30 dB isolation.

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KW - magnet-free isolators

KW - magneto-optical garnets

KW - non-reciprocal mode conversion

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High-Gyrotropy Seedlayer-Free Ce:TbIG for Monolithic Laser-Matched SOI Optical Isolators

Abstract

Bibliographical note

Keywords

UN SDGs

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