Multi-100 Gbit/s optical waveform measurement using sum-frequency-generation optical sampling with subpicosecond supercontinuum pulses

摘要

Ultrahigh-speed optical waveform measurement becomes the key to evaluating ultrahigh-speed/long-distance optical fiber transmission characteristics [1]. Optical sampling based on optical nonlinearity is expected to realize the waveform measurement with subpicosecond temporal resolution. To date, several optical sampling methods have been reported based on sum-frequency-generation (SFG) [2][3], nonlinear optical loop mirror (cross-phase-modulation) [4] and four-wave mixing [5]. However, the temporal resolution was limited to 6～150 ps by the sampling pulse sources such as mode-locked external cavity laser-diodes, gain-switched laser-diodes and Nd:YAG lasers. Recently, we reported 0.63 ps resolution 100 Gbit/s optical waveform measurement using SFG optical sampling with subpicosecond (0.55 ps) sampling pulses by supercontinuum (SC) generated in an optical fiber [6]. In this report, we demonstrate the successful waveform measurement of a 400 Gbit/s optical signal with the improved resolution of 0.44 ps by shortening the pulse duration of the SC sampling pulses down to 0.30 ps. This optical sampling system can measure, with good linearity, optical signal waveforms over wavelength ranges of more than 25 nm around 1.55 μm. Also discussed is the S/N characteristics of the proposed method.