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Optical parametric oscillators without any cavity in novel configurations

Here, we review our results on backward optical parametric oscillators (BOPO)s and transversely-pumped counter-propagating OPOs (TPCOPOs). A TPCOPO does not require a cavity to establish oscillation. Second-order susceptibility of a nonlinear medium is spatially modulated with a period the pump wavelength in the medium to achieve quasi phase matching (QPM).