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Random laser (RL) emission in Nd3+ doped potassium gadolinium tungstate-KGd(WO4)2:Nd3+- crystal powder is demonstrated. The powder was excited at 813nm in resonance with the Nd3+ transition 4I9/2→4F5/2. RL emission at 1067 nm due to the 4F3/2→4I11/2 transition was observed and characterized. An intensity threshold dependent on the laser spot area and bandwidth narrowing from ≈2.20 nm to ≈0.40 nm were observed and measured. For a beam spot area of 0.4mm2, a RL threshold of 6.5 mJ/mm2 (90MW/cm2) was determined. For excitation intensity smaller than the RL threshold, only spontaneous emission from level 4F3/2 with decay time in the tens microsecond range was observed, but for excitation above the RL threshold, significant shortening of excited level lifetime, characteristic of a stimulated process was found. The overall characteristics measured show that KGd(WO4)2:Nd3+ is an efficient material for operation of solid state RLs in the nearinfrared. [ABSTRACT FROM AUTHOR]

Abstract: We report measurements of cross-saturation bandwidth on signal wavelength in single-pumped Thulium doped fiber amplifiers (TDFA) using two different pump wavelengths (1426 and 1050 nm) and a highly doped (5000 ppm) Thulium-doped fiber module. The 1050 nm pump has a lower cross-saturation effect than the 1426 nm, and an increase in cross-saturation is observed as the signal wavelength decreases within the S band. We also experimentally investigated the transient response of a single-pumped TDFA at 1050 nm, and analyze the amount of surviving channel gain, gain excursion and time-constants or the highly doped fibers. [Copyright &y& Elsevier]