Abstract : We demonstrate the optical thyristor operating as optical hard-limiter (OHL) in the optical channel and AND gate logic element (AGLE). The oxidized PnpN vertical-cavity laser (VCL)–depleted optical thyristor (DOT) clearly shows the nonlinear s-shaped current-voltage and lasing characteristics. A switching voltage of 5.24 V, a holding voltage of 1.50 V, and a threshold current of 0.65 mA is measured, making these devices attractive for optical processing applications. The VCL– DOT operating as OHL would enhance the system performance because it would exclude some combinations of interference patterns from causing errors as in all previous works.