Patent ID: 6985282

Claim:
Apparatus for improving the conversion efficiency of optical parametric oscillator having a low conversion efficiency due to the difference between the pumping and signal and idler wavelengths, comprising: a cascaded series of optical parametric oscillators located in a common optical cavity tuned to a predetermined resonant wavelength, each of said optical parametric oscillators having a non-linear crystal; and, a pump laser for pumping the first of said optical parametric oscillators at a wavelength to generate photons at an idler wavelength and a signal wavelength in a parametric process in which pump photons are split into two photons, each having a different one of said idler and signal wavelengths, the output of said first optical parametric oscillator being introduced into the next parametric oscillator, with unused signal photons being used to pump said next optical parametric oscillator, said next optical parametric oscillator having an idler wavelength output having a power which is the sum of the idler outputs of said first and next optical parametric oscillators, whereby unused photons from the first optical parametric oscillator pump a subsequent optical parametric oscillator to promote photon recycling.