Recording of mid-infrared radiation in photochromic polymers

Abstract

A new system for real-time recording of mid-infrared laser radiation, comprising photochromic spiropyran–methylmethacrylate copolymers, is investigated. The laser radiation, derived from a CO2 laser, bleached pre-colored merocyanine, thereby converting it back to spiropyran. The exposure energies at 50% of the initial merocyanine optical density was about 0.1 J/mm2 at 10.6 μm laser wavelength and 0.2 J/mm2 at 10.5 μm. The sensitivity difference at the two laser wavelengths points to differences in thermal energy dissipation mechanisms. A resolution equal or better than 40 lines/mm was achieved, and holographic gratings can be recorded in the mid-infrared.