Laser diode reliability determn. method - measuring noise current in region of threshold current for several frequencies to determine inverse frequency noise

摘要

The inverse frequency noise of the laser diode (DUT) is determined by measuring the noise current. The noise current is measured in the region of the threshold current of the laser diode for several frequencies as a function of its forward current. The decrease in the noise current at low frequencies is used as a criterion for the laser diode's reliability. For a drop of at least 3 dB in the noise current in the region of +/- 20 per cent deviation of the forward current from the threshold current, an evaluation unit signals that the laser diode is reliable. USE - Positive indication of reliability of laser diode still on its semiconducting wafer immediately after its mfr.