Abstract

We recently described and demonstrated a subnanometer-wavelength multiplexing (SWM) system for fiber optical communication.¹ The SWM is implemented using time-domain-holography modulation (TDHM).^2-3 In TDHM, the laser beam is first split into two beams, one of which is reserved as a reference beam. The other is the information beam; it is modulated and frequency-shifted by an acoustooptical (AO) or surface acoustic wave (SAW) modulator. The latter can be used for the system when it is put into integrated optics form. The information and reference beams are then combined and coupled into an optical fiber for transmission. Since a photodiode is a square law detector, beats between the reference and information beams will reproduce the original signal (on a rf subcarrier⁴) at the receiving end. The rf carrier can have a frequency anywhere from several tens of mHz to tens of GHz.

© 1981 Optical Society of America