Importance

Loading Importance Indicators...

Abstract

An optical fiber communications system includes an optical pathway defined as a closed optical loop with a signal source introducing a fixed frequency optical signal onto the loop as a reference signal for system wide propagation. Each terminal device in the system includes a thermally controllable bus tap resonator which can be controlled in a step-wise manner to support plural sets of resonant modes having corresponding different free spectral ranges with one mode of each supported set of resonant modes frequency locked to the system reference signal and another mode used for communications purposes. The bus tap resonators are thermally controlled to allow each terminal device to tune from a first set of resonant modes having a first free spectral range to another set of resonant modes having another free spectral range so that the frequency of the mode used for communications in the latter set will be different from that in the former set. The system reference signal source is preferably defined by a controllable resonant structure, such as a Fabry Perot cavity, which is controlled to lock to the frequency of a stabilized He-Ne laser. A laser diode operating in the desired wavelength band is controlled to lock the wavelength of its output to that of the one of the resonant modes of the stabilized Fabry Perot cavity to thus lock the frequency of the laser diode to that of the highly stable He-Ne laser.

Loading the Abstract Image...

First Claim