All - optical sampling with Sagnac switches using closed pump and signal wavelengths near 1 μm

The optical performance of a Polarization-Maintaining Sagnac switch can be optimized in a simple way by combining the measurement of the energy transfer function with proper modeling and numerical computations. We demonstrate the sampling capabilities with the help of the existing relationship between the expected power transfer function and the experimental data. The effects of coupled Group-Velocity-Dispersion and Self-Phase-Modulation are taken into account, in combination with the limitations in the Polarization-Extinction-Ratio of the loop. Given the rapid decrease of the peak power of the pump pulse along the active section of fiber, the sizing criteria involve the use of high pump powers and lengths of fiber which are shorter than 20 m. The demonstration is implemented with the help of a basic setup which involves two closed wavelengths, i.e. 1062 and 1053 nm for the pump and the signal. This gives the benefit of fast transition times and good polarization maintaining. Efficient optical all-sampling can thus be performed within a wide dynamic range in excess of 30 dB and with a sampling resolution in the range of 2 ps.