November 12, 2004, Madison, Wisconsin--Alfalight announced this week at the Lasers and Electro-Optics Society (LEOS) 2004 annual meeting that it has set a world record for power conversion efficiency in 976-nm diode laser bars.
Developed with support from the DARPA Super High Efficiency Diode Sources (SHEDS) program, Alfalight says it has demonstrated a 50 W, 976-nm laser bar with 71% power conversion efficiency (PCE) at 25 °C and 73% efficiency at 10 °C. This achievement puts Alfalight ahead of schedule in the phase I SHEDS challenge to deliver 65% PCE diode laser bars to DARPA by March 2005, and approaches the 80% PCE targeted for September 2006 as part of SHEDS phase II.
"Alfalight has now established the benchmark for high-power diode laser efficiency," said Tom Earles, chief technology officer of Alfalight. "The past several months have yielded several breakthroughs that rapidly took us from June's 65% efficiency in a 4 W single-emitter to over 71% in a 50 W laser bar. We will integrate these unique high-efficiency aluminum-free active-region (ALFA) diode laser designs into our next generation of commercial products."
The Alfalight team achieved this high efficiency by examining the various sources of loss in the laser and taking steps to remedy each one. Careful bandgap engineering increased the efficiency of carrier injection into the quantum well, the confinement structure was altered to decrease the laser's operating voltage, and waveguide adjustments reduced the losses from scattering and absorption of lasing photons. Progressing toward the 80% SHEDS goal will likely incorporate more aggressive techniques that confine the carriers in two or even three dimensions, further enhancing device efficiency.