VORSTROMREGELUNG VON LASERDIODEN

摘要

The invention relates to a method for the control of the preconduction current for laser diodes which are employed as light transmitters in the transmission stages of light wave guide transmission systems. In such laser diodes, a sharp bend occurs in the lower part of the light current characteristic curve which separates an upper characteristic curve area with great steepness from a lower characteristic curve area with minimum steepness and comparatively high cut-in retardation. Therefore, such laser diodes are operated with a preconduction current whose magnitude corresponds to the threshold current occurring in the characteristic curve bend. Due to aging and temperature influences, displacements of the characteristic curve bend can occur so that a control of the preconduction current is required. To this end, the invention provides that an oscillation of comparatiely lower frequency and low amplitude be superimposed on the preconduction current. A part of the light emitted by the laser diode is monitored for the occurrence of this additional oscillation. The inventive preconduction current regulation of laser diodes is particularly employable in light wave guide transmission systems with high transmission velocities.