OSE Special Seminar with Dr. Brian M. Anderson on Thulium doped all-fiber amplifiers beyond 2.1 μm
Posted: June 5, 2018
Date: Wednesday, June 6, 2018
Time: 11:00 AM to Noon
Location: CHTM, Room 103
Map to CHTM:
Parking passes are available at the receptionist desk. The CHTM building is equipped with ADA accommodations as well as parking spaces.
Dr. Brian M. Anderson
Air Force Research Laboratory, 3550 Aberdeen Ave SE, Kirtland AFB, NM, USA 87117
High power sources operating at wavelengths beyond 2100nm have many applications due to the improved eye safety, improved atmospheric transmission, and reduced absorption in crystals utilized for nonlinear frequency conversion to the mid-infrared. Despite these advantages, power scaling remains a challenge due to the low gain in rare earth doped materials, increased background absorption in fused silica, and high thermal loads due to increased quantum defect.
Thulium-doped amplifiers present the best candidates for power scaling at the ~2000nm wavelength regime, as higher efficiencies can be potentially attained due to the two-for-one cross relaxation process. However, the low emission cross section beyond 2100nm limits the maximum output power due to the growth of spontaneous emission and the onset of parasitic lasing. As a means to suppress detrimental parasitic lasing in thulium-doped fiber amplifiers, we present a novel implementation of laser gain competition (LGC). LGC has previously been used in ytterbium doped fiber amplifiers as a means of suppressing nonlinear effects. Here, by seeding the amplifiers with two seeds, a shorter wavelength seed (1950nm) and the desired output longer wavelength seed (2110nm), the parasitic lasing threshold can be increased by more than 5 times, and efficient output at 2110nm can be obtained. In this work, we demonstrate an output power of 394 W at 2110nm with an optical efficiency of 44%. To our knowledge, this represents the highest power achieved in a long wavelength (>2100nm) Tm-doped all-fiber amplifier with significantly higher overall efficiencies than previously reported tandem pumped Tm/Ho fiber amplifier systems.