Constant modulation index technique for measuring the derivatives of device parameters

Abstract From the Canadian patent

Described is a technique for generating directly certain derivatives of device parameters by measuring the device response to ac modulation under conditions of constant modulation index. In particular the technique as, it applies to measuring directly idF/di and i2d2P/di2 for A1CaAs DN p-a junction lasers is described for two cases: where the generalized function F equals either voltage V across the laser or the light intensity output L of the laser, and i equals current through the laser. For p-n junction lasers this technique permits measurement of the series resistance R?, lasing current threshold ith and the exponential factor?=q/mkT.