ABSTRACT
We report on the development of novel saturable absorbers for erbium lasers based on transparent glass-ceramics (GCs) containing a mixture of cobalt-doped ß-willemite, Co2+:ß-Zn2SiO4, and zinc oxide, Co2+:ZnO, nanosized (10-14 nm) crystals. The structure of the parent glass and GCs is studied by x-ray diffraction, differential scanning calorimetry, transmission electron microscopy, and Raman spectroscopy. Variations of absorption spectra with heat-treatment reveal that Co2+ ions from the parent glass enter the crystals of ZnO and ß-willemite. GCs are characterized by a broad absorption band due to the A24(F4)âT14(F4) transition of Co2+ ions in tetrahedral sites spanning up to â¼1.74 µm, relatively low saturation fluence, FS=0.75 J/cm2 at 1.54 µm, short recovery time, τ=830 ns, and high laser damage threshold, â¼14 J/cm2. By using the developed GCs in a diode-side-pumped Er, Yb:glass laser, 0.77 mJ/45 ns pulses are generated.
ABSTRACT
A new saturable absorber Q switch for 1.54-mum Er:glass lasers is presented. The saturable absorber is a transparent glass ceramic that contains magnesium-aluminum spinel nanocrystallites doped with tetrahedrally coordinated Co(2+) ions. We obtained Q-switched pulses of up to 5.5 mJ in energy and 80 ns in duration at 1.54 mum. The relaxation time of (4)A(2) ?(4)T(1)((4)F) transition bleaching was measured to be (450 ? 150) ns. Ground-state and excited-state absorption cross sections at 1.54-mum wavelength were estimated to be (3.2 ? 0.4) x 10(-19) cm(2) and (5.0 ? 0.6) x 10(-20) cm(2), respectively.
