Continuous-wave tunable optical parametric generation in a photonic-crystal fiber

Continuous-wave and quasi-cw operation of tunable optical parametric generation has been demonstrated in a photonic-crystal fiber. The frequency shift of the generated sidebands, which arise from modulation instability, depends strongly on the detuning of the pump from the fiber’s zero-dispersion wavelength. Over $30\mathrm{nm}$ of sideband tunability has been demonstrated using a $300\mathrm{mW}$ cw pump, and over $185\mathrm{nm}$ of tunability using a $1.6\mathrm{W}$ quasi-cw pump. Continuous wave and quasi-cw pumps eliminate the detrimental effects of pump–sideband walk-off. In the absence of walk-off it is the fluctuations in the index profile of the photonic-crystal fiber along its length that limit the tunable sideband range.