Page 320 - Introduction to Information Optics

6.2. Polymer Waveguides 305

On the other hand, Ultradel polyimides and Cyclotenes (BCB) are well known
for applications in electronic circuit boards as protective dielectric layers,
Further, they form good-quality optically transparent thin films. Compatibility
with the microelectronic fabrication process, however, is the thermal require-
ment for the polymer material to survive wire-bonding and metal deposition
processes. Ultradel polyimides from Amoco Chemicals stand out in this aspect,
as they exhibit thermal stability to above 400°C.

6.2.2. FABRICATION OF LOW-LOSS POLYMERIC WAVEGUIDES
In order to realize high-performance waveguide-based optical interconnects,
the optical polymeric waveguide must be designed and fabricated for low
scattering and bending losses. To fabricate such polymeric waveguide circuits,
we investigated three waveguide fabrication technologies [12-15]:
* Compression-molding technique,
' VLSI lithography technique, and
" Laser-writing technique.
Figure 6.2 shows the schematic diagrams of these three waveguide fabrica-

Fig. 6.2. Schematic diagrams of three polymeric waveguide fabrication technologies developed at
Radiant Research, Inc.