ELECTRONIC APPARATUS AND INSTRUMENTS, NAMELY OPTICAL AMPLIFIER AND LASER MODULES WITH CONTROL CIRCUITRY, LASER MODULES WITH OPTICAL MODULATORS AND CONTROL CIRCUITRY; OPTICAL APPARATUS AND INSTRUMENTS, NAMELY LASER ARRAYS IN PLANAR WAVEGUIDES, LASERS IN RARE-EARTH-DOPED PLANAR WAVEGUIDES NOT FOR MEDICAL USE, OPTICAL AMPLIFIERS, LOSS-LESS/AMPLIFYING DEVICES, OPTICAL POWER EQUALIZERS, OPTICAL MULTIPLEXERS, OPTICAL DEMULTIPLEXERS, OPTICAL FILTERS, OPTICAL ADD-DROP MULTIPLEXES, OPTICAL TRANSMITTER...