Spectroscopy and green upconversion laser emission of Er3+-doped crystals at room temperature

Publisher Website
Google Scholar
Abstract
The spectroscopic parameters of Er3+‐doped crystals were determined with regard to the upconversion laser parameters of the green transition 4S3/2→4I15/2. The influence of excited‐state absorption on this laser channel was determined. Furthermore, upconversion pump mechanisms using ground‐state and excited‐state absorption around 810 and 970 nm were investigated by direct measurements of excited‐state absorption. The spectroscopic results confirm the pulsed room‐temperature laser experiments on the 4S3/2→4I15/2 transition. The lasers based on Er:LiYF4, Er:Y3Al5O12, and Er:Lu3Al5O12 were directly excited into the upper laser level by an excimer laser pumped dye laser in the blue spectral range. In Er:LiYF4, Er:KYF4, and Er:Y3Al5O12, laser action was achieved with two‐step upconversion pumping by a Ti:sapphire laser and a krypton ion laser. In the case of the fluorides, the additional pumping with the krypton ion laser was not necessary. The laser emission wavelengths were 551 nm for Er:LiYF4, 561 nm for Er:Y3Al5O12 and Er:Lu3Al5O12, and 562 nm for Er:KYF4. In addition, green quasi‐cw laser emission of Er:LiYF4 pumped with an argon‐ion laser was realized at room temperature.