Noncritically phase-matched fourth harmonic generation of Nd:glass lasers in partially deuterated KDP crystals

摘要

Noncritically phase-matched (NCPM) fourth harmonic generation (FHG) of Nd:glass laser radiation in partially deuterated dihydrogen phosphate (KD~(*)P) crystals has been demonstrated. At an Nd:glass laser wavelength of 1053.0nm, NCPM FHG is achieved in 70percent deuterated KD~(*)P at a crystal temperature of 18.5 +- 0.1 deg C. Tuning the fundamental laser wavelength from 1052.9 to 1053.2 nm, FHG in KD*P is NCPM by changing the crystal temperature from 17.9 deg C to 20.5 deg C. When driven with 2.4 J of second harmonic radiation in a 3 ns flat-top pulse, corresponding to 1 GW/cm~(2) 2omega drive intensity, 1.9 J of fourth harmonic radiation was generated in a 6mm long KD~(*)P crystal, yielding a second to fourth harmonic energy conversion efficiency of 79percent.