Electrical noise of laser diodes measured over a wide range of bias currents

The electrical noise of commercially available laser diodes, an index guide d AlGaInP diode lasing at 635 nm (SDL3038-11) and an InGaAlP-multiquantum w ell diode lasing at 670 nm (SVL71B), has been investigated over a wide curr ent range of six orders of magnitude. After increasing proportionally with current at small currents (10 nA to 10 muA), the 1/f noise tends to saturat e with increasing current in the range from 10 to 100 muA. For larger opera ting currents, the 1/f noise increases again, and with the current proporti onal to I-2. Different noise sources were discovered below the lasing thres hold current. The electrical noise at lower currents must be measured to as sess the degradation of the active region of the laser diode. (C) 2000 Else vier Science Ltd. All rights reserved.