We proposed and demonstrated a new all-polymer based fabrication process for an all-polymer flexible and parallel
optical interconnect cable in which a vertical light coupler is integrated. The approach potentially cut down the cost by
eliminating a metallization process for alignment of multiple masks. Throughout the process we used a polyimide as the
substrate, coated by Epoclad as claddings, then AP2210B and WPR 5100 were used to fabricate waveguides and 45
degree mirror couplers, respectively. In addition, precisely aligned mirror couplers to waveguides are achieved by using
polymer-based, non-metallic, and transparent phase-based alignment marks. We tested a feature specific phase-based
alignment system. In addition, the shape and depth of the phase-based alignment marks are optimized for phase contrast
and Schlieren imaging. Our results shows that a contrast of the image is enhanced compared to that of observed by a
conventional imaging system. Such process enables to integrate polymer based waveguides by only using the polymer
based alignment marks on the WPR 5100 layer.
We have developed a hybrid lithography process necessary to fabricate a vertical optical coupler and an array of waveguide structures using the same buffer coat material on a single substrate. A virtual vernier scale built into the process enables precise alignment of both structures.
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
We utilized a hybrid lithography technique in the fabrication of a 45 degree micro mirror coupler to be used for a 3D
optical circuit. The hybrid process combines traditional mask-based lithography techniques with mask-less methods.
The result is a CMOS compatible process that can be used for fabrication of integrated micro-optics.