Single-core and Dual-core Fiber Optical Parametric Oscillators

We report on two designs for fiber-optic parametric oscillators (FOPOs): a single-core system which exhibits interesting polarization behavior, and a dual-core design which we expect will provide wavelength flexibility and exponential gain. In a single-core FOPO, polarization-based output coupling leads to an increase of output power by 20$\% $-30$\% $ compared with a non-polarization-based output coupling. We present a geometrical visualization of the polarization through the Poincare sphere and compare with experimental results. The coupling coefficient between cores in a dual-core FOPO provides additional phase-matching flexibility. Our proposed dual-core fiber has a coupling coefficient of 0.42 $m^{-1}$ and nonlinear coefficient of 1.6 $W^{-1}{km}^{-1}$ in a weakly guided mode which should deliver exponential gain dependence on the pump power under a variety of conditions. We anticipate that this system will be a unique platform for quantum optics where signal and idler photons are generated indistinguishably in both cores of the fiber.