Energy Transfer For Better Efficiency Of Nd(III) Lasers

Rare earths incorporated in solids are the most popular solid laser devices to date, covering the infrared range from about one micron to about three microns. These consist of single lasing species, such as holmium, neodymium and erbium, or of a combination of different species to enable the system to lase at higher efficiency at room temperature. An example of such systems is the recent demonstration of a room temperature system lasing at about 2 microns, which utilizes a sophisticated scheme of three-stage energy transfer from chromium to holmium and thulium [1]. Recently an Er( III) glass laser operating on two- and three-fold upconversion has been demonstrated [2]. Of the above-mentioned systems by far the most important commercially is the Nd(III) laser, lasing at 1.04-1.07 μm, which is known to operate in a multitude of glasses and crystals [3-4]. Importance of this ion for laser industry prompted an intense worldwide research aimed toward increase of slope efficiency of the Nd(III) lasers and toward decrease of the lasing threshold. In the present paper we shall examine briefly the main advantages and disadvantages of the Nd(III) laser and propose the ways to overcome the disadvantages illustrated by practical examples.