High bandwidth constant current modulation circuit for carrier lifetime measurements in semiconductor lasers

Abstract

In this paper we present a novel implementation of high bandwidth constant modulation current circuit to the traditional small signal optical response technique used to determine the differential carrier lifetime of a semiconductor laser. This circuit is designed for the voltage to current conversion and to deliver a constant modulation current to the laser diode. The circuit rectifies parasitic effects of high value surface mount resistor at high frequencies used in the impedance independent optical technique and also has lower crosstalk. The application of this circuit can be generalized where the requirement arises for a high bandwidth constant modulation current circuit.