• Featured in Physics
  • Open Access

Ultracompact Photonic Circuits without Cladding Layers

Tongtong Song, Hongchen Chu, Jie Luo, Zizheng Cao, Meng Xiao, Ruwen Peng, Mu Wang, and Yun Lai
Phys. Rev. X 12, 011053 – Published 21 March 2022
Physics logo See Viewpoint: Cladding-Free Photonic Circuits Boost Dense On-Chip Integration

Abstract

Cladding layers of waveguides prevent interchannel interference yet are unfavorable for the integration of photonic circuits. Here, we report the realization of ultracompact waveguide arrays, bends, and circuits with essentially zero interchannel separation. This supercompactness is achieved via arrays of waveguides with shifted spatial dispersions, where each waveguide functions as both the transmission channel and an effective “cladding layer” of its neighboring waveguides, and has been experimentally realized in low-loss all-dielectric photonic crystals. We show that the zero-spacing transmission array possesses the remarkable features of negligible crosstalk, high-efficiency sharp bending, and ultracompact photonic routing where the light can traverse the entire physical space. This finding opens a new avenue for extreme space utilization efficiency in waveguide physics and integrated photonics.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
6 More
  • Received 26 June 2021
  • Revised 3 January 2022
  • Accepted 8 February 2022

DOI:https://doi.org/10.1103/PhysRevX.12.011053

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Viewpoint

Key Image

Cladding-Free Photonic Circuits Boost Dense On-Chip Integration

Published 21 March 2022

A waveguiding mechanism completely removes the cladding layers that are part of today’s photonic circuits, like building highways without median strips for light.

See more in Physics

Authors & Affiliations

Tongtong Song1,§, Hongchen Chu1,§, Jie Luo2,§, Zizheng Cao3, Meng Xiao4, Ruwen Peng1,*, Mu Wang1,5,†, and Yun Lai1,‡

  • 1National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
  • 2School of Physical Science and Technology, Soochow University, Suzhou, 215006, China
  • 3Institute for Photonic Integration, Eindhoven University of Technology, P.O. Box 5135600 MB Eindhoven, Netherlands
  • 4Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
  • 5American Physical Society, 1 Research Road, Ridge, New York 11961, USA

  • *Corresponding author. rwpeng@nju.edu.cn
  • Corresponding author. muwang@nju.edu.cn
  • Corresponding author. laiyun@nju.edu.cn
  • §T. S., H. C., and J. L. contributed equally to this work.

Popular Summary

Are walls necessary to build a labyrinth? For photons, the answer could be “no.” In all previous waveguide systems, including photonic chips, cladding layers have been considered indispensable to confine the waves to the core layer, just like a wall in a maze. But such claddings occupy most of the space in photonic chips and severely hinder efforts to increase waveguide integration density. To solve this issue, we propose a principle to realize ultracompact photonic circuits without claddings: photonic labyrinths without “walls.”

The major innovation here is to integrate waveguides designed with different inherent momenta to form cladding-free waveguide systems, where the photons propagating in each waveguide cannot couple into their neighboring waveguides because of momentum mismatch. We realize cladding-free waveguide arrays, 90° sharp bends, and photonic circuits with coiled-up paths using pure dielectrics, which we demonstrate with microwave experiments. Simulations show that this principle also applies to the optical frequencies via common optical materials like silicon and silicon dioxide.

Our discovery goes beyond the traditional paradigm of waveguide physics by reducing, for the first time, the huge amount of space occupied by claddings in the waveguide systems to zero. It opens a new route to further enhance the density of photonic integration, which is a crucial indicator for the photonics industry.

Key Image

Article Text

Click to Expand

References

Click to Expand
Issue

Vol. 12, Iss. 1 — January - March 2022

Subject Areas
Reuse & Permissions
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review X

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

×

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×