Wavelength Tunable Light Source, 50GHz/0. 4nm Interval, C or L Band ITU Grid, 20mW, PM Fiber The Light Source is a Fiber coupled diode Laser of standard ITU DWDM wavelength with Min. C and L band are. Powerful LEDs enable a wide range of applications – and can be adapted to just as many specific requirements. Our motorized components, complex filter concepts and integrated trigger functions turn light sources into intelligent lighting systems. It is the spontaneous radiation generated by semiconductor laser pumping erbium-doped quartz fiber. At the same time, the. AFL is a trusted supplier of optical testing equipment with more than 30 years of experience and tens of thousands of units in use in the field. Essential building blocks for fiber testing, EXFO offers optical light.