Telecommunication fiber optic systems, namely, optical circuits and devices for use in metro access, namely, direct modulated lasers, semiconductor lasers, laser transmitter modules, [ continuous wave lasers, ] directly modulated lasers, light emitting diodes, laser diodes, solid-state lasers, optical signal converters, receiver modules, receiver modules with clock or data recovery circuits, video-on-demand modules; [ photodetectors, photodiodes, ] transceivers, transponders, multiplexers, de...