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Q-switched and cw operation of different diodepumped erbium-ytterbium doped glasses at 1.5 μm has been studied in a compact microlaser setup. For Q-switching we used a novel PbS semiconductor quantum-dot doped glass which offers low saturation intensity compared with typical absorbers used and a fast time response. The cw laser delivered output powers of 35 mW with slope efficiencies of 16%. In Q-switched operation pulse energies of 1 μJ at repetition rates of 1–2 kHz and pulse durations of about 30–50 ns, depending on absorber thickness were obtained. PACS: 42.55.Xi; 42.60.Gd; 42.70.Hj The eyesafe wavelength region of the optical spectrum (1.5–1.6 μm) is favoured for applications such as telemetry and ranging [1–4]. Erbium ions in glass hosts are the material of choice if a laser directly emitting in this spectral region without use of nonlinear frequency conversion is desired. Numerous studies in this field have been carried out on actively [2, 4] as well as on passively Q-switched lasers [5, 6]. For compactness, simplicity, and robustness in everyday use the research tends towards diode-pumped passively Q-switched setups [7], avoiding maintenance neccesary for flashlamp pumping and additional electronic equipment required for active switching. Saturable absorbers currently used are erbium [8], uranium [9] and cobalt [10] ions in different crystal hosts. All absorbers are used in resonator setups of a few centimeter length, setting a limit for compactness. All of these absorbers have a relatively high saturation intensity of about 40–200 MW/cm2. In a diodepumped setup these intensities are normally not accessible with single-emitter laser-diode pump-sources with pump powers of 1–2 W. The use of semiconductor quantum-dot doped glass is an interesting possibility to overcome this problem. With an saturation intensity of 0.18 MW/cm2 in PbS-doped glass [11] complete bleaching of the absorber is possible with the intensities achievable in a standard microlaser setup. Another way for Q-switching is the use of semiconductor saturable absorber mirrors [5, 7] which offer a similar saturation characteristic based on quantum wells with their one-dimensional confinement of electronic states in contrast to the three-dimensional confinement in quantumdots. Their production process is complicated because of the sophisticated MOCVD techniques necessary for production of these devices. Semiconductor quantum-dot doped glasses on the other hand can be produced by common melting techniques well known and elaborated in glass technology and can be easily tuned in their spectral properties by changing the quantum-dot size by different growth conditions. Details about the glass composition are to be found in [12].

Erratum: Diode-pumped erbium-ytterbium-glass laser passively Q-switched with a PbS semiconductor quantum-dot doped glass