Chiral spiral waveguides based on MMI crossings

Theory and experiments

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

We introduce a novel type of chiral spiral waveguide where the usual waveguide crossings are replaced by 100:0 Multimode Interferometers (MMIs), i.e. 2x2 splitters that couple all the input light in the cross output port. Despite the topological equivalence with the standard configuration, we show how resorting to long MMIs has non-trivial advantages in terms of footprint and propagation length. An accurate analytic model is also introduced to show the impact of nonidealities on the spiral performances, including propagation loss and cross-talk. We have designed and fabricated three chiral spirals on our platform, based on 3 μm thick silicon strip waveguides with 0.13 dB/cm propagation loss, and 1.58 mm long MMIs. The fabricated spirals have 7, 13 and 49 loops respectively, corresponding to the effective lengths 6.6 cm, 12.5 cm and 47.9 cm. The proposed model is successfully applied to the experimental results, highlighting MMI extinction ratio of about 16.5 dB and MMI loss of about 0.08 dB, that are much worse compared to the simulated 50 dB extinction and 0.01 dB loss. This imposes an upper limit to the number of rounds, because light takes shortcuts through the bar MMI ports. Nevertheless, the novel chiral spiral waveguides outperform what is achievable in mainstream silicon photonics platforms based on submicron waveguides in terms of length and propagation losses, and they are promising candidates for the realization of integrated gyroscopes. They can be significantly further improved by replacing the MMIs with adiabatic 100:0 splitters, ensuring lower cross-talk and broader bandwidth.

Original languageEnglish
Title of host publicationSilicon Photonics XI
PublisherInternational Society for Optics and Photonics SPIE
ISBN (Electronic)9781628419870
ISBN (Print)978-1-6284-1987-0
DOIs
Publication statusPublished - 1 Jan 2016
MoE publication typeA4 Article in a conference publication
EventSilicon Photonics XI - San Francisco, United States
Duration: 15 Feb 201617 Feb 2016

Publication series

NameProceedings of SPIE
PublisherSPIE
Volume9752
ISSN (Print)0277-786X

Conference

ConferenceSilicon Photonics XI
CountryUnited States
CitySan Francisco
Period15/02/1617/02/16

Fingerprint

Interferometer
Interferometers
Waveguide
Waveguides
interferometers
waveguides
Experiment
Propagation
Experiments
propagation
Crosstalk
Silicon
Extinction
extinction
platforms
Topological Equivalence
Silicon Photonics
Light extinction
Gyroscope
Gyroscopes

Keywords

  • Integrated Optics
  • Multimode interference splitters
  • Photonic Integrated Circuits
  • Silicon Photonics

Cite this

Cherchi, M., Ylinen, S., Harjanne, M., Kapulainen, M., Vehmas, T., & Aalto, T. (2016). Chiral spiral waveguides based on MMI crossings: Theory and experiments. In Silicon Photonics XI [975215] International Society for Optics and Photonics SPIE. Proceedings of SPIE, Vol.. 9752 https://doi.org/10.1117/12.2210945
Cherchi, Matteo ; Ylinen, Sami ; Harjanne, Mikko ; Kapulainen, Markku ; Vehmas, Tapani ; Aalto, Timo. / Chiral spiral waveguides based on MMI crossings : Theory and experiments. Silicon Photonics XI. International Society for Optics and Photonics SPIE, 2016. (Proceedings of SPIE, Vol. 9752).
@inproceedings{dc11e81ee64744bbbd5a3b29ba5d71c4,
title = "Chiral spiral waveguides based on MMI crossings: Theory and experiments",
abstract = "We introduce a novel type of chiral spiral waveguide where the usual waveguide crossings are replaced by 100:0 Multimode Interferometers (MMIs), i.e. 2x2 splitters that couple all the input light in the cross output port. Despite the topological equivalence with the standard configuration, we show how resorting to long MMIs has non-trivial advantages in terms of footprint and propagation length. An accurate analytic model is also introduced to show the impact of nonidealities on the spiral performances, including propagation loss and cross-talk. We have designed and fabricated three chiral spirals on our platform, based on 3 μm thick silicon strip waveguides with 0.13 dB/cm propagation loss, and 1.58 mm long MMIs. The fabricated spirals have 7, 13 and 49 loops respectively, corresponding to the effective lengths 6.6 cm, 12.5 cm and 47.9 cm. The proposed model is successfully applied to the experimental results, highlighting MMI extinction ratio of about 16.5 dB and MMI loss of about 0.08 dB, that are much worse compared to the simulated 50 dB extinction and 0.01 dB loss. This imposes an upper limit to the number of rounds, because light takes shortcuts through the bar MMI ports. Nevertheless, the novel chiral spiral waveguides outperform what is achievable in mainstream silicon photonics platforms based on submicron waveguides in terms of length and propagation losses, and they are promising candidates for the realization of integrated gyroscopes. They can be significantly further improved by replacing the MMIs with adiabatic 100:0 splitters, ensuring lower cross-talk and broader bandwidth.",
keywords = "Integrated Optics, Multimode interference splitters, Photonic Integrated Circuits, Silicon Photonics",
author = "Matteo Cherchi and Sami Ylinen and Mikko Harjanne and Markku Kapulainen and Tapani Vehmas and Timo Aalto",
year = "2016",
month = "1",
day = "1",
doi = "10.1117/12.2210945",
language = "English",
isbn = "978-1-6284-1987-0",
series = "Proceedings of SPIE",
publisher = "International Society for Optics and Photonics SPIE",
booktitle = "Silicon Photonics XI",
address = "United States",

}

Cherchi, M, Ylinen, S, Harjanne, M, Kapulainen, M, Vehmas, T & Aalto, T 2016, Chiral spiral waveguides based on MMI crossings: Theory and experiments. in Silicon Photonics XI., 975215, International Society for Optics and Photonics SPIE, Proceedings of SPIE, vol. 9752, Silicon Photonics XI, San Francisco, United States, 15/02/16. https://doi.org/10.1117/12.2210945

Chiral spiral waveguides based on MMI crossings : Theory and experiments. / Cherchi, Matteo; Ylinen, Sami; Harjanne, Mikko; Kapulainen, Markku; Vehmas, Tapani; Aalto, Timo.

Silicon Photonics XI. International Society for Optics and Photonics SPIE, 2016. 975215 (Proceedings of SPIE, Vol. 9752).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

TY - GEN

T1 - Chiral spiral waveguides based on MMI crossings

T2 - Theory and experiments

AU - Cherchi, Matteo

AU - Ylinen, Sami

AU - Harjanne, Mikko

AU - Kapulainen, Markku

AU - Vehmas, Tapani

AU - Aalto, Timo

PY - 2016/1/1

Y1 - 2016/1/1

N2 - We introduce a novel type of chiral spiral waveguide where the usual waveguide crossings are replaced by 100:0 Multimode Interferometers (MMIs), i.e. 2x2 splitters that couple all the input light in the cross output port. Despite the topological equivalence with the standard configuration, we show how resorting to long MMIs has non-trivial advantages in terms of footprint and propagation length. An accurate analytic model is also introduced to show the impact of nonidealities on the spiral performances, including propagation loss and cross-talk. We have designed and fabricated three chiral spirals on our platform, based on 3 μm thick silicon strip waveguides with 0.13 dB/cm propagation loss, and 1.58 mm long MMIs. The fabricated spirals have 7, 13 and 49 loops respectively, corresponding to the effective lengths 6.6 cm, 12.5 cm and 47.9 cm. The proposed model is successfully applied to the experimental results, highlighting MMI extinction ratio of about 16.5 dB and MMI loss of about 0.08 dB, that are much worse compared to the simulated 50 dB extinction and 0.01 dB loss. This imposes an upper limit to the number of rounds, because light takes shortcuts through the bar MMI ports. Nevertheless, the novel chiral spiral waveguides outperform what is achievable in mainstream silicon photonics platforms based on submicron waveguides in terms of length and propagation losses, and they are promising candidates for the realization of integrated gyroscopes. They can be significantly further improved by replacing the MMIs with adiabatic 100:0 splitters, ensuring lower cross-talk and broader bandwidth.

AB - We introduce a novel type of chiral spiral waveguide where the usual waveguide crossings are replaced by 100:0 Multimode Interferometers (MMIs), i.e. 2x2 splitters that couple all the input light in the cross output port. Despite the topological equivalence with the standard configuration, we show how resorting to long MMIs has non-trivial advantages in terms of footprint and propagation length. An accurate analytic model is also introduced to show the impact of nonidealities on the spiral performances, including propagation loss and cross-talk. We have designed and fabricated three chiral spirals on our platform, based on 3 μm thick silicon strip waveguides with 0.13 dB/cm propagation loss, and 1.58 mm long MMIs. The fabricated spirals have 7, 13 and 49 loops respectively, corresponding to the effective lengths 6.6 cm, 12.5 cm and 47.9 cm. The proposed model is successfully applied to the experimental results, highlighting MMI extinction ratio of about 16.5 dB and MMI loss of about 0.08 dB, that are much worse compared to the simulated 50 dB extinction and 0.01 dB loss. This imposes an upper limit to the number of rounds, because light takes shortcuts through the bar MMI ports. Nevertheless, the novel chiral spiral waveguides outperform what is achievable in mainstream silicon photonics platforms based on submicron waveguides in terms of length and propagation losses, and they are promising candidates for the realization of integrated gyroscopes. They can be significantly further improved by replacing the MMIs with adiabatic 100:0 splitters, ensuring lower cross-talk and broader bandwidth.

KW - Integrated Optics

KW - Multimode interference splitters

KW - Photonic Integrated Circuits

KW - Silicon Photonics

UR - http://www.scopus.com/inward/record.url?scp=84981301299&partnerID=8YFLogxK

U2 - 10.1117/12.2210945

DO - 10.1117/12.2210945

M3 - Conference article in proceedings

SN - 978-1-6284-1987-0

T3 - Proceedings of SPIE

BT - Silicon Photonics XI

PB - International Society for Optics and Photonics SPIE

ER -

Cherchi M, Ylinen S, Harjanne M, Kapulainen M, Vehmas T, Aalto T. Chiral spiral waveguides based on MMI crossings: Theory and experiments. In Silicon Photonics XI. International Society for Optics and Photonics SPIE. 2016. 975215. (Proceedings of SPIE, Vol. 9752). https://doi.org/10.1117/12.2210945