The realization of a ridge waveguide linear mode-confinement modulator using reactive ion-beam etching is discussed. With the help of a design analysis, the modulation characteristics are predicted. Along with the measured modulation characteristics, preliminary results of the calibration of ion-beam etching in Z-cut LiNbO//3 by Ar and a mixture of Ar and CHF//3 are presented. Differential etching rates of as high as 7 between photoresist and LiNbO//3 are obtained. Using the proposed design of a ridge waveguide linear modulator, a linear modulation of over 67% is measured.