A novel electroabsorption modulator (EAM) using intrastep quantum wells (IQWs) and a single-sided large optical cavity waveguide is demonstrated to operate at up to 100 mW of input optical power. When the IQW EAM with uncoated facets is tested in an analog fiber link, the radio-frequency link gain reaches -16.1 dB at 100-mW optical power. We have measured a single-octave spurious-free dynamic range (SFDR) of 121 dB (.) Hz(4/5) and multioctave SFDR of 110 dB (.) Hz(2/3) for this EAM.