We have observed a new type of infrared-induced photodarkening in high-numerical-aperture fluoride fibers doped with 3000 and 10,000 parts in 106 by weight of Tm. The loss induced in the visible region by 1140-nm radiation is very strong (as high as 25 dB in a 50-cm piece) and broadband; it can be removed by irradiation with the same pump wavelength at lower powers.
© 1995 Optical Society of America
Original Manuscript: June 26, 1995
Published: November 1, 1995
P. R. Barber, R. Paschotta, A. C. Tropper, and D. C. Hanna, "Infrared-induced photodarkening in Tm-doped fluoride fibers," Opt. Lett. 20, 2195-2197 (1995)