Transmission properties of polymer optical fibers for pulsed UV laser light

Laser spectroscopy in the UV-region below 380 nm is a powerful tool for many biomedical or analytical applications. For such purposes Polymer Optical Fibers (POFs) can be an interesting alternative to silica-based optical fibers if the transmission in the UV-A region is sufficient. In addition to high-power LED-light delivery shown in previous studies, the short and long term performance of PMMA-based POFs under pulsed UV radiation was investigated using a nitrogen laser at 337 nm and the 3rd harmonic of Nd:YAG laser at 355 nm. For thick POFs (core diameter: approx. 1000 mu m), the basic (initial) low intensity UV-attenuation is in the order of less than 2 dB/m. However, a typical initial attenuation between 4 and 5 dB/m was determined using the pulsed UV-Iasers. At 337 nm, the transmission for these POF is independent of intensity up to 9 MW/cm(2). No photodegradation was observed, up to 180k pulses if the intensity does not exceed 6 MW/cm(2). For both wavelengths, the surface damages have been observed, taking into account the differently shaped intensity-profiles.