System for controlling photo-output

Abstract

Abstract PURPOSE:To reduce the photo-output error regardless of the magnitude of the mark ratio of the data input signal and that of the reference voltage by controlling the loop system so that the ratio between the voltage corresponding to the photo-output and the reference voltage corresponding to the electric signal input becomes constant. CONSTITUTION:An electric input is applied to a driving circuit 1, and a laser 2 is driven by means of the photo-output of the driving circuit 1 to generate a photo- output. A part of the photo-output is derived by a mirror 3 or the like and it is converted into an electric signal by means of a PIN diode 4 and an output voltage V0 is added to one input terminal of a dividing circuit 10 through an amplifier 5. A DC reference voltage Vs from a resistor R and a capacitor C corresponding to an electric input is added to the other input terminal of a dividing circuit 10, and division with the output voltage Vo corresponding to the photo-output is carried out in the division circuit 10. The thus divided output V1 is compared with a reference value V in a comparator 11. The driving circuit 1 is controlled so that the ratio of the comparison results becomes constant, and the photo-output error is reduced in spite of the magnitude of the mark ratio of the input signal and that of the reference voltage Vs.

Inventors

• 👤 Yasuhiro Tanaka

Bibliographic Details