Highly Efficient, High-Power Pump Diodes from 790nm to 2um

One of the major limitations to scaling diode laser power is the waste heat in the semiconductor, which can be addressed by improvements in power conversion efficiency. Here we report on the rapid advancement of conversion efficiencies across all commercial pump wavelengths from near- to mid-infrared. The most critical improvements have been the reduction in the diode laser operating voltage through optimization of hetero-barriers, leading to 74% efficient 100 W bars for pumping ytterbium lasers between 915 and 975 nm. We review our efforts at extending high efficiencies to neodymium pump wavelengths at 880, 885 and 808 nm, in addition to shorter wavelengths where we are now achieving over 70% efficiency for pumping thulium lasers around 792 nm. Results will also be presented for high efficiency InP devices for pumping holmium at 1907 nm and erbium at 1470 nm up to 37 W and 100 W per bar, respectively