A novel optical sampling scheme using an electroabsorption (EA) modulator as the sampling component is presented that will greatly reduce the complexity of presented schemes. The 10-GHz optical analog signal's waveform is measured, with a 100 MHz waveform observed on an oscilloscope. The relationship between the EA sampling width and sampling bandwidth is analyzed using a two-step model, which is presented for the first time. Calculation indicates that the Gaussian-shaped filter can perfectly simulate the effect of the EA sampling width. Detailed analysis also reveals that the optical sampling with an EA modulator is a promising scheme for measuring waveform signals in future optical networks.