How is DCG affected by DWDM and input signal conditions?
A. There is hardly any absorption in a phase grating. The more common reflection gratings absorb as much as 20% and get really hot. It is not uncommon for communication signals to be between 5 and 50 mw, so adding up a hundred or more channels is a lot of heat. The gratings can take the heat but the losses at the fiber ends will be measured in watts, so heat dissipation probably has to be considered in a device’s package. Total absorption and scatter in the grating is about 2 or 3% so it is not a problem. Depending upon the glue, it can begin to soften or degrade between 10 to 100 watts per square cm continuous wave. Properly hardened gelatin can withstand >100 watts per square cm continuous wave. Peak power from pulsed laser energy applications can have energy densities in the megawatts. See our Pulsed Laser page.
