Incoherently pumped continuous wave optical parametric oscillator   broadened by non-collinear phasematching
  In this paper, we report on a singly resonant optical parametric oscillator (OPO) pumped by an amplified spontaneous emission (ASE) source. The pump focusing conditions allow non-collinear phasematching, which resulted in a 230 nm (190 cm$^{-1}$) spectral bandwidth. Calculations indicate that such phasematching schemes may be used to further broaden OPO spectral bandwidths. 
Jelle Storteboom, Chris J. Lee, Ab F. Nieuwenhuis, Ian D. Lindsay and   Klaus-J. Boller
physics.optics