Trivalent zirconium and hafnium ions in yttria-based transparent ceramics
Electron paramagnetic resonance spectra of transparent yttria-based ceramics with zirconium and hafnium additives contain signals with close parameters due to paramagnetic Zr3+ and Hf3+ ions, which have similar ground-state electron configurations of [Kr]4d1 and [Xe]5d1, respectively.
Fabrication and optical properties of Y2O3-based ceramics with broad emission bandwidth
Abstract In this article, we report on the fabrication and optical properties of highly transparent yttria ceramics for lasers active media with broadband gain profile. Laser synthesis method was used to produce Y2O3-based nanopowders doped with 1 mol.% Nd3+ or Yb3+ for these transparent ceramics. The additives of sesquioxides Lu2O3 and Sc2O3 were used along with ZrO2 to disorder the crystalline structure. The porosity and average grain size decrease with these additives and the emission bandwidths of Nd3+ (4F3/2 → 4I11/2) and Yb3+ (2F5/2 → 2F7/2) transitions widen to 40 and 60 nm, respectively. Laser operation with the slope efficiency of 29% was obtained in [(Yb0.01Lu0.24Y0.75)2O3]0.88(ZrO2)0.12 ceramic sample.
Highly efficient repetitively pulsed electric-discharge industrial CO2 laser
The results of investigations aimed at the development of a repetitively pulsed CO2 laser with an active medium volume of 1000 cm3 pumped by a combined discharge are generalised. It is shown that, at pump pulse durations of 200–500 μs the optimal characteristics are achieved at active-medium pressures of 60–100 Torr. In this case, the laser efficiency at the initial stage of its operation can reach 22% and; if the energy dissipated in the region of the cathode potential drop is neglected, the efficiency is 28%. After emission of 3×105 pulses, the laser efficiency falls to 12%. It has been found that adding CO with a relative concentration [CO]/[CO2] ~0.75 increases the input and output power by almost 50%. The lasing efficiency is then 10%—12%, and the service life of the laser is by more than 106 pulses with a power decrease of no more than 10%. Adding hydrogen up to a concentration [H2]/[CO2] ~10 leads to an increase in the energy supplied to the gas due to a decrease in the rate of ionisation processes. However, the optimal ratio is [H2]/[CO2] ~ 1, at which the output power increases by 15%. In a long-term operating mode, the laser power is 1 kW at a peak power of 10 kW and an efficiency of 12%.