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Two-photon-absorption-induced photochromic reactions in spirobenzopyran-doped PMMA waveguides

Multimode spirobenzopyran (SP) doped PMMA channel waveguides have been fabricated and one- and two-photon absorption induced photochromic reactions have been demonstrated in these waveguides. Bleaching of SP was performed by coupling a 0.75-mW, 543nm beam into these guides. Two-photon absorption based coloring was demonstrated using two counterpropagating pulses, one at 1064 nm and the other at 532 nm. We measured the coupling efficiency to be 0.168, which gave intensities inside the guide of 10.494 GW/cm2 and 7.765 GW/cm2 for the IR and the green beams, respectively. The ability to shift the colored spot via pulse delay in the counterpropagating pulse scheme was also demonstrated by moving a colored spot by approximately 30 micrometers . Finally, two-photon induced fluorescence was observed by exciting the waveguide with a single 1064-nm beam at an intensity of approximately 10 GW/cm2.