Solution: The occurrence of this failure phenomenon indicates that there is a problem with the optical path. What Can I Do? First, please check that the optical cable which comes. Light is part of the "electromagnetic spectrum" that also includes x-rays, ultraviolet radiation, microwaves, radio, TV, cell phones, and all the other wireless signals. They are simply electromagnetic radiation of different wavelengths. Explore several modulation schemes including amplitude modulation and. cal source by varying the current through the source. An optical source converts el ctrical energy (current) into optical energy (light).