Noise suppression of a blue upconversion fiber laser

Summary form only given. Visible upconversion fiber lasers in the blue spectral range offer an alternative to air cooled argon ion lasers. A multiple photon absorption process of near infrared pump photons allows an efficient excitation of high energy levels from which laser transitions in the visible spectral range are possible. The Pr,Yb:ZBLAN-fiber used in our experiments can be excited by a single mode laser diode at a wavelength around 850 nm and yields five laser transitions between 491 nm and 717 nm.