High-brightness tapered lasers with an Al-free active region at 1060 nm

摘要

High-brightness diode lasers at 1060 nm are useful in display applications (to provide green light by frequency doubling) and in free-space optical communications. On Al-free active region laser structures, we have obtained low optical losses of 0.9 cm~(-1), a high internal quantum efficiency of 98% and a low transparency current density of 64 A/cm~2. On uncoated broad-area lasers (2 mm × 100 μm) at 20℃ CW, we have obtained a high maximum wall-plug efficiency of 66%, and an optical power higher than 3W per facet. Based on these good results, we have realized 3.7 mm long gain-guided tapered lasers, delivering a high power of 3W at 10℃ CW, together with a low M~2 of 3 at 1/e~2 and a high maximum wall-plug efficiency of 57%. We have also realized separate electrode lasers, in which the ridge and tapered sections are biased separately. In this configuration, the current through the ridge section is only a few tens mA while the current on the tapered section is several Amps. This allows to control a large output power with only a small change of the ridge current. By moving the ridge current from 0 to 50 mA, keeping a constant 4A current through the tapered section, we have obtained a large change of the output power from 0.09 W to 2.6 W, which corresponds to a high modulation efficiency of 50 W/A under static operation. In dynamic regime, the separate electrode laser can be operated at 700 Mbps, showing a high modulation efficiency of 19 W/A, optical modulation amplitude of 1.6 W and extinction ratio of 19dB. These modulation efficiencies are, to our knowledge, record values.