Photodetecting Assembly as Detection System for Weak Optical Signals

Abstract

A broad class of optoelectronic systems is designed for detection of weak pulsed signals [1, 5–10]. It would be easier to name those systems which use unmodulated radiation (exposure meters, some automatic systems) than to enumerate all systems working with modulated radiation. In some of the latter modulated is the source itself — such are the devices based on pulsed lasers and LEDs: geodesic laser range finders, fiber optical telecommunication systems, reflectometers (devices for locating breaks in fiber optical cables by timing the return of the pulse bounced off the faulty spot), active tracking and aiming systems (such as coordinators). In some optoelectronic systems the source is not modulated, and the task consists in defining the coordinates of the point source. The pulsed signal in such systems is caused by modulation and scanning in the system, or by the movement of the point source. Such systems include star orientation devices, IR direction finders, various kinds of passive tracking and aiming systems. Even if the radiation of the source is constant, and there is no modulation or scanning in the system, the measurement time Tm is still limited, and the optical signal may be considered as a pulse of length Tm.KeywordsDark CurrentSpace Charge RegionOptoelectronic SystemInternal GainPhotosensitive ElementThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.