We make an attempt to develop a novel approach to experimental investigations of highrepetition‐ rate trains of picosecond optical pulses. For this purpose an opto‐electronic system for detecting train‐average time parameters had been created. The scheme of this system consists of optical auto‐correlator, electronic controller, and a set of the checking units. The computer admits several regimes for operation: calibration of optical autocorrelator, measuring cycle, and data processing and display. Initially, pulse trains arrive at the optical auto‐correlator, i.e. at a two‐beam scanning Michelson interferometer, which is formed by two total‐internal‐reflection prisms and a 50%‐mirror. The prismatic optical circuit permits keeping out the backward scattering from basic reflecting planes of the optical auto‐correlator. During the measuring cycle, the moving prism changes its position step‐by‐step. The scheme utilizes an interferometric technique of detection: the reflected optical signals form an interferogram, which is registered by a slow‐speed photodetector, amplified, converted into binary format, and finally goes to computer, which controls the whole process. As a result, all the data related to cycle time‐average auto‐correlation function of pulse trains is stored in the computer memory and the train‐average pulse parameters are calculated. For visual displaying of auto‐correlation function, the detected electronic signal arrives at an external memory oscilloscope. The checking units receive another part of pulsed radiation after interferometer. By using a high‐speed photodetector and a sampling oscilloscope, one can observe the character of light radiation. The temporal picture is characterized by the fact that optical pulse interval is true, but the pulse envelope is determined by the response time inherent in a high‐speed photodetector, whose bandwidth was about 3.5 GHz, so that adequate pulse width measuring was possible only when auto‐correlation responses were exploited. This optoelectronic system is acceptable for ultra‐short pulse characterization within the range from one to a few tens picoseconds.

Peer reviewed