What could cause a laser source with fiber coupled laser diodes to have extreme loss of power? The laser diodes have a wavelength of 658nm and have an output rated at 60mW but it seems as though the optical channels actually output ranges between 58 to 70mW. During some troubleshooting I noticed that one of my optical channels had a loss of -13dB (95%) so I cleaned the fibers to make sure there was no blockage but when I remeasured I was only given a small gain of maybe +30dB (0.1%). I decided to spot check other channels and noticed that they also had significantly dropped in power. I thought that perhaps the sources had been on for too long and that perhaps the diodes where being affected by heat, I shut everything down and proceeded to check the systems the next day after they had cooled but unfortunately the output was still extremely low.