Optical apparatus including an optical frequency conversion device, pumped by a non-polarized light beam. The apparatus may include a pump incident side, such as an optical fiber emitting non-polarized light beam, a polarization beam splitter to split the incident beam into two polarized beams, beam forming optics to shape the beams and rotate their polarization as required and couple them into the conversion device, and an optical frequency conversion device to convert the wavelength of both beams into a new wavelength.