A bias-free two-section Y-branch directional coupler modulator with high linearity based on domain-inverted modulation is fabricated and tested. 25 wt.% AJLS102/APC is used as an active core layer with an experimentally confirmed device r(33) value of 56 pm/V at 1.59 microm. The fabricated device shows an extinction voltage of 4 V. A two-tone test is performed to demonstrate 64 dB distortion suppression at 25% modulation depth, which is 22 dB higher than a conventional Mach-Zehnder modulator.