300-mJ diode-pumped 1.9-μm Tm:YLF laser

Abstract

ABSTRACT We report on a diode pumped Tm: YLF laser generating 1.9µm output. Recently, research is being pursued to produce laser wavelength around 2µm by separating the Ho and Tm ions in different laser hosts [1,2] . Compared to co-doped laser hosts; a higher efficiency performance can be achieved by directly pumping the Holmium with a 1.9µm Tm laser due to the elimination of energy sharing between Tm and Ho as well as deleterious upconversion effects in co-doped systems. A 300-mJ Tm:YLF laser at room temperature has been demonstrated. The laser design and laser performance is described. To our knowledge, this is the highest energy ever reported for this laser material. Keywords: Lasers and laser optics, diode-pumped solid state lasers, eye-safe lasers, Rare earth and transition metal solid-state lasers, Tm doped lasers. 1. INTRODUCTION The last decade has seen a growing interest in eye-safe, high energy, efficient 2µm lasers. Applications of these lasers range from remote sensing of the atmosphere to medical and air transport safety. Atmospheric sensing lidars can benefit from high energy, eye-safe laser transmitters. The long 2µm lifetime is amenable to multiple Q-switched operations, which is ideal for DIAL application. In addition to pumping Ho laser crystals to generate the wavelength around 2 µm for lidar transmitter applications, laser sources around 1.9µm can have numerous applications in the medical field as stand-alone lasers. Tm doped YLF lasers are very attractive due to their versatility and their various transitions in the near infrared. It has been shown that by lowering the doping concentrations to avoid cross-relaxation, the 2.3µm radiation can be enhanced at the