We have theoretically analyzed the depleted optical thyristor structure and experimentally demonstrated optical logic gates implemented by monolithically integrated vertical cavity laser--depleted optical thyristor (VCL-DOT) for an optically programmable gate array. The optical AND-and OR-gates have been realized by changing a input bias of the single VCL-DOTs and all kinds of optical logic functions are also implemented by adjusting an intensity of the reference input beams into the differential VCL-DOTs. To achieve the high sensitivity and low threshold current, a small active region of lasing part and a wide detecting area are simultaneously designed by using a selective oxidation process..