<title>Fiber-guided tunable UV-laserlight system around 215 nm</title>

Abstract

Silica based optical fibers are in operation for light-guidance in many applications, with wavelengths ranging from 230 nm to 2.2 .tm. At shorter wavelengths, UV-improved fibers (UVI) can be used, which overcome the significant generation of UV-defects and associated loss in throughput using broadband deuterium-lamps or UV-lasers with fixed wavelengths such as excimer-lasers and quadrupled Nd:YAG lasers. Alternatively, many spectroscopic applications need a tunable and powerful UV-light to carry out remote-measurements, in-situ. In addition, specialized fiber-optics probe may be useful.We will report for the first time on the transmission properties of the UVI-fibers with high-power pulsed lasers with wavelengths in the vicinity of the dominant UV-defect at 215 nm using a frequency-doubled dye-laser, tunable from 206 to 245 nm. Due to the high intensity of this pulsed laser system, especially near the fiber frontface, two-photon absorption plays a major role with decreasing wavelength. Therefore, properties such as starting transmission and UV-induced loss were measured as a function of the wavelength and input pulse energy.The envelope of the wavelength-dependent induced losses is comparable with results taken from tests with low-power broadband deuterium-lamps. However, the temporal behaviour during recovery is quite different.