All-optical sampling oscilloscopes are key measurement equipment for research and development of ultrahigh-speed optical communication systems and photonic switching networks. This paper briefly reports our experimental work on the design and implementation of a prototype system for ultra-wide bandwidth all-optical sampling oscilloscopes, and it also presents the preliminary results obtained from our experiment on the development of such an oscilloscope prototype system. Using our developed passively mode-locked fiber laser of high stability as an optical sampling pulse source, we successfully demonstrate the all-optical sampling of optical pulse sequences with pulse width of 1.8 ps at the repetition rates of 10 GHz and 40 GHz, respectively, by means of the four-wave mixing (FWM) in a highly nonlinear fiber. Then the waveforms of ultrashort optical pulse signals are reproduced by using digital signal processing and computer image processing, respectively, in our prototype system which displays the measured optical pulses with a width of 2.3 ps. With our developed optical sampling oscilloscope prototype, we also successfully perform the accurate measurement of optical eye diagrams for 10Gbit/s and 40 Gbit/s optical data signals (of 1.8 ps pulse width) which are modulated with a pseudorandom bit sequence, respectively. This is the first report in China about the practical development work on ultra-wide bandwidth all-optical sampling oscilloscope equipment and the associated experimental test results. The obtained results on all-optical waveform measurement of ultrashort optical pulse signals are also compared with those measured by the conventional optoelectronic measurement system consisting of a 70 GHz wideband electronic oscilloscope and an ultrafast photodetector. It is shown clearly that our developed all-optical sampling oscilloscope prototype has much higher temporal resolution and larger system bandwidth than a conventional optoelectronic measurement system does.