RESUMO
A mode-locked thin-disk laser based on Yb:CALGO is demonstrated for the first time. At an average output power of 28 W we obtained pulses with a duration of 300 fs and a pulse energy of 1.3 µJ. 197 fs pulses with 0.9 µJ of energy were achieved at an average output power of 20 W. The shortest pulse duration measured in our experiments was 135 fs with a spectrum centered at 1043 nm. The experiments also revealed a very broad tunability from 1032 to 1046 nm with sub-200 fs pulses.
RESUMO
We present the first demonstration of a Yb:CALGO thin-disk laser. In a slightly multimode configuration, we obtained up to 30 W of average power at a slope efficiency of 40% and an optical-to-optical efficiency of 32%. With a single-mode cavity, an average power of 25 W was achieved. A tuning range from 1018 to 1052 nm could be demonstrated by inserting a prism into the cavity. In the Q-switched regime, we obtained 1 mJ of pulse energy at a repetition rate of 100 Hz.
RESUMO
Sodium niobate (NaNbO3, or NNO) is known to be antiferroelectric at temperatures between 45 and 753 K. Here we show experimentally the presence of the ferroelectric phase at temperatures between 100 and 830 K in the NNO crystals obtained by top-seeded solution growth. The ferroelectric phase and new phase transitions are evidenced using a combination of thermo-optical studies by variable angle spectroscopic ellipsometry, Raman spectroscopy analysis, and photoelectron emission microscopy. The possibility for strain-induced ferroelectricity in NNO is suggested.
Assuntos
Cristalização/métodos , Campos Magnéticos , Nióbio/química , Sódio/química , Teste de Materiais , Conformação Molecular , Transição de FaseRESUMO
Using KNbO(3) crystals for second-harmonic generation in the blue spectral range, we have obtained conversion efficiencies as high as 53.7%. To our knowledge this value is the highest reported for a pulsed laser. A gainswitched nanosecond Ti:sapphire oscillator, amplified by a Cr:LiSrAlF(6) multipass amplifier, was used as the fundamental light source. The maximum energy obtained at the harmonic wavelength of 430 nm was 38 mJ for a bandwidth of 230 MHz.
RESUMO
The transition of the single-frequency oscillation of a semilinear photorefractive coherent oscillator for sufficiently large coupling strengths into two-frequency oscillation is predicted and is observed experimentally. The critical value of the coupling strength at which the bifurcation occurs is a function of pump intensity ratio and cavity losses. The supercritical bifurcation in the oscillation spectrum is analogous to the second-order phase transition.