In this paper, we propose a WDM optical true time-delay (OTTD) beam former for phased way antenna (PAA) systems. It is composed of a delay lines matrix and a multiwavelength source with discrete DFB laser diodes. The building block of a delay lines matrix is a $2 imes2$ optical MEMS switch with proper fiber-optic delay line connected between cross ports. A $4 imes3$ matrix using four DFB lasers has been fabricated with unit time-delay difference of 12 ps. Maximum time-delay error was measured to be -1.74 ps and +1.14 ps at a radiation angle of $46.05^{circ}$, corresponding to error range of $-2.87^{circ}sim+1.88^{circ}$. By measuring time-delays at six different RF frequencies from 5- to 10-GHz, we verified the true time-delay characteristic of our OTTD.