High brightness eyesafe optical parametric oscillator using confocal unstable resonators

Tunable middle IR optical parametric oscillator for spectroscopic applications

“…As pump energy increases, the difference is becoming smaller and it vanishes at 190 mJ pump energies. A similar result was shown in [2]. This fact is also illustrated in Fig.…”

“…The reduced energy around 6.4 µm can be explained by water absorption in the air. The threshold is below the value stated before [2], but the slope efficiencies are lower, too. In contrast to that, the slope efficiencies of this OPO are higher than the ones stated in [8], but the threshold is higher, too.…”

“…The divergence was 4.5 mrad in flat-flat cavity case and 3.2 mrad in unstable cavity case. Further fine tuning of the set-up could produce much smaller divergence [2]. But the advantage of the unstable cavity is obvious, and an improvement in the divergence is enough to pump the second stage of tandem OPO system, as it is shown below.…”

“…Employment of unstable resonators allows getting low enough divergence of multimode nanosecond OPO. The advantages of using these modifications have been demonstrated recently [2][3][4].…”

Optical parametric master oscillator and power amplifier for efficient conversion of high-energy pulses with high beam quality

“…The problem with transverse mode control has been addressed by use of confocal unstable resonators [4][5][6][7][8], where the magnification reduces the divergence. This type of resonator has the useful property that the beam is well collimated in the forward direction, but the large divergence in the return pass limits the efficiency of two-pass pumping in critically phasematched crystals, making it more difficult to achieve a short build-up time.…”