Abstract

We have measured an effective two-photon absorption coefficient in a lead glass fiber (SF6 core with SF56 cladding). This effective two-photon absorption coefficient has contributions from true two-photon absorption and also from the formation of absorbing defect centers. It is strongly dispersive, ranging from 0.02 cm /GW at 1.06 μm to over 1.5 × 10⁴ cm/GW at 458 nm, with a sharp rise as the wavelength becomes shorter than 0.5 μm. Such high values render the fiber ineffective for all-optical switching in the visible but suggest applications to optical limiting.¹ The absorbing defects appear to be created through two- photon absorption of the laser and removed through one-photon absorption. The net absorption may be described by an effective two-photon absorption coefficient in steady state. It appears that a substantial portion of this effective two-photon absorption coefficient at the shorter wavelengths is due to these absorption centers.

© 1989 Optical Society of America