Spun Coat Bragg Crystal Development

Mary Louise Gucik, Laura Biedermann, Brad Jones, Christian Arrington, Ron Goeke, Ryan Goodner, Tim Lambert, Kylie Manning, Mike Sinclair, Dave Wheeler

Sandia National Laboratories

As trust in the performance of devices and parts relies on our ability to monitor and record service history, prevent counterfeiting and detect unknown or nefarious property changes, the need for highly selective sensing capabilities is essential. To achieve this goal, an optical sensor was created to react to UV and X-ray light through a combination of chemical and optical amplification. Light sensitive polymers were created by doping an active polymer with a photoacid generator (PAG) to deprotect after the absorbance of a photon. The light sensitive polymer and an inert polymer were spun coat in alternating fashion on silicon substrates creating a bi-layer Bragg crystal. Following X-ray exposure with an iodonium PAG, a decrease of 17 ±9% was seen in one crystal bilayer; UV absorbance showed a 33 ±11% decrease. The decreased thickness results in a permanent shift in optical reflection that is clearly observable to the naked eye.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.