Description
Backward-wave optical parametric oscillators (BWOPOs) are mirrorless parametric devices in which signal and idler waves propagate in opposite directions. Under incoherent pumping, this geometry makes it possible to achieve coherent backward-wave generation over a substantially wider pump-wavelength range than conventional parametric devices. Here, we numerically simulate an incoherently pumped PPKTP crystal to study the coherence properties of the backward wave and demonstrate that its spectral narrowing depends on pump wavelength. Analytical iterative solutions based on the Riemann integration method further confirm the underlying mechanism. To date, however, these effects in the temporal-domain have not been verified experimentally. Their observation would require an incoherent subnanosecond pump source delivering very high pulse energies on the order of 100 µJ.
