Concentration quenching of luminescence lifetime in ytterbium-doped potassium double tungstate waveguide amplifiers

Abstract

Integrated optical amplifiers employing ytterbium-doped potassium double tungstates exhibit an ultra-high peak gain exceeding 1000 dB/cm, in addition to a broad gain of up to 150 dB/cm over a 55-nm wavelength range. Here we report a study of the luminescence lifetime in samples spanning a broad range of dopant concentrations (1.2−57.5 at.%). By use of the pinhole method, elongation of the luminescence lifetime due to radiation trapping is avoided, providing a more accurate analysis of concentration quenching of the luminescence lifetime, which directly influences the waveguide amplifier performance and can, in principle, inhibit scaling of the gain with increasing dopant concentration