This study demonstrates the lasing characteristics of InGaAs/InGaAsP multiple-quantum-well waveguide-type depleted optical thyristor using the vertical window. The measured switching voltage and current are 3.36 V and 10 μA, respectively. The lasing threshold current is 131 mA at 25 °C. The output peak wavelength is 1570 nm at a bias current of 1.22 Ith and there is no input signal. The vertically injected depleted optical thyristor shows very good isolation between input and output signals.