Highly sensitive optical-sampling system using a periodically poled lithium niobate crystal

Summary form only given. An optical sampling system using sum-frequency generation (SFG) can measure waveforms having high bit rate signals for optical communications. Such a system, however, requires a signal peak power of at least a few mW to achieve a 20-dB signal-to-noise ratio (SNR) because the conventional KTiOPO/sub 4/ (KTP) nonlinear optical crystal for SFG has low conversion efficiency. In this study, we measured the SNR of an optical sampling system that uses a periodically poled LiNbO/sub 3/ (PPLN) crystal, and observed the eye diagram of a 10-Gbit/s optical signal having less than I-mW peak power.