Polarization-insensitive optical sampling system using two KTP Crystals

We have successfully developed a polarization-insensitive optical sampling system with a two-path configuration based on sum-frequency generation (SFG) using two KTiOPO/sub 4/ (KTP) crystals. The orthogonal polarization components of the signal pulse are optically sampled independently and combined in an avalanche photodiode. The difference in SFG conversion efficiency between each path is compensated by choosing a suitable ratio to divide the sampling pulse. The polarization dependence of the system was less than 3.5% (0.15 dB) in the wavelength range from 1520 to 1620 nm.