A medical laser system and related methods of monitoring optical fibers to determine if an optical fiber cap on the optical fiber is in imminent danger of failure. The laser system includes a photodetector for converting returned light from the optical fiber cap to an electronic signal for comparison to a trigger threshold value known to be indicative imminent fiber cap failure. The returned light can be the main laser treatment wavelength, an auxiliary wavelength such as an aiming beam or infrared wavelengths generated by a temperature of the optical fiber cap. In the event the electronic signal reaches the trigger threshold value, the laser system can be temporarily shut-off or the power output can be reduced.