High-average-power SRS conversion of radiation in a BaWO₄crystal

An intracavity, frequency-doubled BaWO_4 Raman laser generating multi-watt continuous-wave, yellow emission

“…The removal of active cooling of the BaWO 4 crystal did not appear to impact the yellow powers achieved from the resonator, and therefore we believe that the resultant thermal lensing within the BaWO 4 crystal was small in comparison to the thermal lens generated within the Nd:GdVO 4 crystal. Thermal lenses generated in BaWO 4 by Raman heating have previously been reported as being weak [22]. We were unable to use our estimate of thermal load in the BaWO 4 crystal to calculate the corresponding thermal lens focal length, because we were unable to find a published value for the thermo-optic coefficient in BaWO 4 .…”

Stimulated Raman Scattering in Alkali-Earth Tungstate and Molybdate Crystals at Both Stretching and Bending Raman Modes under Synchronous Picosecond Pumping with Multiple Pulse Shortening Down to 1 ps

“…Such systems are synchronously pumped Raman lasers [67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82]. If we use a train of ultra-short pulses with the pulse train duration of t p at the individual pulse duration of τ p , the extracavity synchronously pumped SRS oscillation threshold will be defined by expression (12) where τ p should be replaced with t p and p = 1 for both ring and linear cavities (at τ p < τ c we have gain only in the forward direction) but the SRS gain G (and its threshold value G th in expression (12)) is defined by τ p as before by expression (8). Using mode locking for the pump laser, it is easy to obtain a very high value of t p (quasi-continuous-wave mode-locking) and even continuous-wave mode-locking ( t p → ∞ ).…”

Thermal lens evolution and compensation in a high power KGW Raman laser

“…In molecular ion Raman crystals, such as the alkali or alkalis-earth nitrates and tungstates, thermal effects are evident even for average output powers around the single or multi-watt level [2,3]. Higher powers (>5 W) have been obtained by compensating for lensing in the resonator design [4,5], or using materials with improved thermal characteristics such as barium tungstate [6,7] and diamond [8][9][10][11]. As part of the on-going drive for higher powered devices, it is important to understand how the crystal heating affects performance and to determine methods for compensation or circumvention.…”