Efficient refractive-index modification of fused silica by a resonance-photoionization-like process using F(2) and...

Novel materials processing by a multiwavelength excitation process using F(2) and KrF excimer lasers for high-efficiency and high-speed refractive-index modification of fused silica is demonstrated. We find this process to be essentially superior to single-wavelength F(2) -laser processing: The multiwavelength excitation process achieves more than twice the diffraction efficiency of fused silica modified by a F(2) laser at the same total number of photons in each irradiated laser beam supplied to the fused-silica substrate. This superiority is attributed to a resonance-photoionization-like process based on excited-state absorption.