SBIR-STTR Award

Improving efficiency as well as increasing operating temperature of laser diode pumps for high-power fiber lasers has a far-reaching implication in terms of significantly improving the overall stringent size, weight and power (SWAP) requirements, thus enabling DEW-class fiber lasers on airborne platforms. As a result, there is currently great interest in the further development of high-power, high-efficiency, fiber-coupled diode laser pumps around 975 nm that operate at higher ambient temperatures. nLight has demonstrated world-class high-power and high-efficiency laser diodes at 975 nm. Using these successful techniques and innovative diode design concepts, nLight will optimize 975-nm laser diodes to produce maximum efficiency at 70 C and higher operating temperatures. nLight will develop higher thermal conductivity submounts in order to reduce junction temperature of the diodes, therefore achieving maximum efficiency at high operating temperatures. In addition, nLight will significantly reduce optical-to-optical losses of the fiber coupling architecture, thus maintaining the electrical-to-optical power conversion efficiency of the diode laser pumps. Under the proposed Phase 1 program, nLight will design, fabricate, and deliver to the Navy (or recipient of its choosing) a 25-W, 975-nm fiber-coupled (200 m / 0.22 NA) laser module with a power conversion efficiency of >65% at 25 C.

Benefit:
The high efficiency and high temperature diode pump system proposed herein is principally motivated by airborne directed energy weapons (DEW) enabled by high power Yb-doped fiber laser amplifiers. The pump diodes to be developed will ultimately lead to smaller, lighter, and less complex laser systems suitable for scaling to the power levels required for directed energy applications. In the commercial sector, direct diode systems based delivering such brightness are expected to displace CW fiber lasers as the architecture of choice for low cost, reliable industrial laser cutting, welding and brazing systems. nLight is an active supplier of turnkey direct diode laser systems used in such applications. nLight has a good track record of commercializing the results of DoD-funded research, and expects to commercialize the results and devices produced under this program as rapidly as possible.

Keywords:
985 nm, 985 nm, Fiber-coupled diode laser pump, fiber laser, High efficiency, High Temperature

Based on the promising results obtained under Navy Phase I SBIR funding, nLight proposes a Phase II continuation toward the development of fiber-coupled high power and high efficiency diode laser pumps around 975 nm that operate at high ambient temperatures. Under the Phase I SBIR base program, nLight designed, demonstrated, and delivered to Navy a 30-W, 975-nm fiber-coupled (200 m / 0.15 NA) laser module with fiber-coupled power conversion efficiency of >63% at 25C. This is achieved through diode laser epitaxy design optimization, improvement in heatsink thermal resistance for lower diode junction temperature, and improvement in the optical-to-optical fiber-coupling efficiency of the diode laser pump. In the proposed Phase II effort, nLight will address the key area of required improvement high temperature operation while maintaining high efficiency and scaling up power. At the end of the Phase II base program, nLight will deliver to Navy (or a recipient of its choosing) a 25-W, 975-nm fiber-coupled (200 m/0.22 NA) laser module with a power conversion efficiency of >57% at 70C. At the end of the Phase II option program, nLight will deliver to Navy a >100W, 975-nm fiber-coupled (200 m/0.22 NA) laser module with>70% conversion efficiency at 70C.

Benefit:
The high efficiency and high temperature diode pump system proposed herein is principally motivated by airborne directed energy weapons (DEW) enabled by high power Yb-doped fiber laser amplifiers. The pump diodes to be developed will ultimately lead to smaller, lighter, and less complex laser systems suitable for scaling to the power levels required for directed energy applications. In the commercial sector, direct diode systems based delivering such brightness are expected to displace CW fiber lasers as the architecture of choice for low cost, reliable industrial laser cutting, welding and brazing systems. nLight is an active supplier of turnkey direct diode laser systems used in such applications. nLight has a good track record of commercializing the results of DoD-funded research, and expects to commercialize the results and devices produced under this program as rapidly as possible. Manufacturability has been considered from the bottom up in the approach proposed herein.

Keywords:
fiber laser , High efficiency, 975 nm, High Temperature, Fiber-coupled diode laser pump