Transmitting information optically by modulating carrier signal

摘要

Optical conductors are used for the modulated carrier signals which are recovered at the reception side by demodulation using a filter. Only such carrier signals are utilised that possess a power or energy density spectrum with a periodic or approximately periodic variation for the frequency involved. The filter (62) has the structure of a Fabry-Perot etalon and possesses a semi-transmissive mirror (64), a second mirror (66) and an adjusting element (68) or micro-screw. An optical medium (70) with a diffraction index is installed between the mirrors.