Thermal-stress-induced birefringence management of complex laser systems by means of polarimetry

Abstract

The novel method of the thermally-induced polarization changes driven power losses (TIPCL) analysis in the complex laser systems has been developed. The measurement has been tested on the amplifier chain of the 100 J / 10 Hz laser system ‘Bivoj’ operated at HiLASE Centre. By the usage of the measured non-uniform Mueller matrix of the amplifier chain, the optimization of the ideal input and output polarization state has been calculated numerically. The results of the optimization have been applied to the laser system, thus reducing the TIPCL from originally observed more than 33% to 7.9% for CW beam and to 9% for pulsed laser beam, respectively. To the best of our knowledge, this result represents the most efficient TIPCL suppression method for complex laser systems so far. The method also allows the definition of the ideal fully polarized non-uniform pre-compensation of input beam consequently suffering from zero TIPCL.

Kilowatt-class high-energy frequency conversion to 95 J at 10 Hz at 515 nm

“…If only the output polarization is optimized, the energy losses decrease further to 32% (Figures 2(e) and 2(f)). By using a custom polarimetric technique to evaluate the Mueller matrix of the Bivoj system [ 11 ] , we were able to estimate numerically the optimal input polarization to further decrease the energy losses to around 3% (Figures 2(g) and 2(h)). These results were obtained for output energy of 90 J, helium flow rate of 150 gps (gallons per second) and temperature of 120 K. We optimized the polarization homogeneity at lower energy output to avoid changes to the beam, as the maximum output energy is close to laser induced damage threshold of the optical components.…”

“…It is, to the best of our knowledge, the highest average power in a high-energy system with energy of more than 1 J with a wavelength around 500 nm and corresponds to 58% increase in the state-of-the-art. Conversion efficiency of 79% was achieved by using flat top beam and pulse profiles and by successful optimization of depolarization by the polarimetric method [ 11 ] .…”

Beam shaping in the high-energy kW-class laser system Bivoj at the HiLASE facility

“…As a result, it reduces the energy available to polarization-sensitive experiments or degrades the beam profile when the beam passes through any diattenuator. These polarization changes were mitigated by injecting optimized polarization into the amplifier [ 23 ] .…”

AC zero crossing compensation for thermal stress linear birefringence in optical voltage transducer

“…The TSLB is also received extensive research in other research fields. For example, the power loss caused by the TSLB of the laser system is investigated in [17], and the laser system has a large number of optical components, so the issue of TSB is much more complicated than the OVT. The TSLB in the Nd:YAG slab of the laser system is calculated and analyzed in [18].…”