Picosecond parametric Raman laser based on KGd(WO4)2 crystal

Simultaneous frequency up and down conversion using a biharmonically pumped parametric Raman laser (PRL) based on a KGd(WO₄)₂ (KGW) crystal has been demonstrated experimentally. Collimated beams have been generated for both the 1st anti-Stokes (1AS) at 511 nm and 2nd Stokes (2S) at 579 nm by four-wave parametric Raman interaction. To excite PRL biharmonically, we pumped the KGW crystal with 20 ps pulses at the fundamental 530 nm and its 1st Stokes component at 555 nm. The 1st Stokes pump beam was generated using stimulated Raman scattering in a separate KGW Raman oscillator. The energy conversion efficiencies reached experimentally were 10% for the 2S and 4% for the 1AS.