Optical subcarrier communications

One of the simplest ways to exploit the large information bandwidth of an optical carrier is to place radio-frequency subcarrlers on the optical beam which can, in turn, be modulated. The subcarrier approach to optical communications permits the use of a variety of established data processing techniques and may assume many levels of sophistication, depending on the particular mission to be performed. With appropriate post-detection electronic processing, the following missions may be accomplished: Distance and velocity measurement. Angle measurement and tracking. Phase-locked receiver tracking. Multichannel telemetry. Television. The use of optical beams in these missions requires a careful consideration of the optical-electronic interface. In particular, the modulation of the beam and its effect on photodetection devices must be examined.