High contrast and metal-less alignment process for all-polymer optical interconnect devices

Tao Ge, Jilin Yang, Chris Summitt, Sunglin Wang, Lee Johnson, Melissa Zaverton, Tom Milster, Yuzuru Takashima

Research output: Chapter in Book/Report/Conference proceedingConference contribution


A polymer-based flat, flexible and parallel optical interconnect has become an attractive approach for short-range data transfer. For such a device, a low cost fabrication technique is required for light couplers to redirect light from source to waveguides. Recently, we demonstrated a mask-less gray scale lithography process, which used a CMOS compatible polymer for a 45-degree mirror coupler. Polymer materials such as epoclad and AP2210B can be used to fabricate flexible substrates and waveguides, respectively. We propose an all-photopolymer lithography process to fabricate the flexible and parallel optical interconnect in conjunction with the mirror couplers. In the process, a buried polymer structure is used to precisely align the mirror coupler to waveguides, which make it possible to avoid an additional metallization process. However, the contrast of such buried fiducial mark is low since such the structure is a phase structure. As a result, it is not feasible to use the buried polymer structure as an alignment mark with conventional amplitude based imaging modalities. To increase the contrast of these buried alignment marks, we propose a feature specific alignment system for which the shape and depth of the buried alignment marks are optimized for phase-based imaging such as phase contrast and Schlieren imaging. Our results show that an optimized alignment mark provides a significant contrast enhancement while using a phase contrast imaging system compared to that of a conventional imaging system. In addition, we have fabricated an optimized alignment mark specifically for use with a Schlieren imaging system.

Original languageEnglish (US)
Title of host publicationAdvanced Fabrication Technologies for Micro/Nano Optics and Photonics VIII
EditorsWinston V. Schoenfeld, Georg von Freymann, Raymond C. Rumpf
ISBN (Electronic)9781628414646
StatePublished - 2015
EventAdvanced Fabrication Technologies for Micro/Nano Optics and Photonics VIII - San Francisco, United States
Duration: Feb 8 2015Feb 11 2015

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherAdvanced Fabrication Technologies for Micro/Nano Optics and Photonics VIII
Country/TerritoryUnited States
CitySan Francisco


  • 45-degree mirror coupler
  • Schlieren imaging
  • lithography
  • optical interconnect
  • phase contrast imaging
  • phase-based alignment marks

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


Dive into the research topics of 'High contrast and metal-less alignment process for all-polymer optical interconnect devices'. Together they form a unique fingerprint.

Cite this