Optical transmission of video signals using pulse time modulated sub-carriers over optical delays carriers

Use of pulse time modulated (PTM) subcarriers in optical links represents an attractive alternative for transmitting analog and digital signals over optical fiber channels. A novel approach for the optical transmission of multiplexed audio and video signals using a pulse width modulated (PWM) electrical subcarrier over optical delays is reported in this paper. The generation optical delays, is achieved by Lithium Niobate (LiNbO₃) electro-optic retarders, which act, at the same time, as optical modulators. Under this technique, an optical delay is generated when 45° polarized light is injected and travels through a LiNbO₃ birefringent optical waveguide. The optical delay can be modulated by the electrical subcarrier and transmitted through an optical fiber channel. At the receiver, the electrical subcarrier can be recuperated only when a second optical delay, which is matched to the transmitter´s one, is introduced. An experimental set-up for transmitting multiplexed audio and video signals using a PWM electrical subcarrier over optical delays is reported in this paper.