Monolithic cascadable laser logic-device arrays are realized and characterized. The monolithic surface-emitting laser logic (SELL) device consists of an AlGaAs superlattice lasing around 780 nm connected to a heterojunction phototransistor (HPT) in parallel and a resistor in series. Arrays up to 8 x 8 are fabricated, and 2 x 2 arrays show uniform characteristics. The optical logic output is switched off with 40-muW incident optical input.