Photonic switching in bulk semiconductor material is of great interest in pulsed power'-3 and microwave applications4. Such interest stems from the low jitter, fast rise time, and high power capabilities of the photonic switch. For long pulse applications4, however, it is often necessary for the switch to remain closed long after the laser pulse is terminated. Such switch behavior is desirable in order to achieve higher efficiency, as well as to accommodate the longer pulse. Recently it was found that GaAs switches exhibit "lock-on" behavior, i.e., the switch recovery times to increase provided the applied electric field and light intensity levels exceed threshold values. In this study we have found that gridded bulk GaAs photonic switches exhibit lock-on behavior. With laser light from a 20 ns Q-switched Nd:YAG laser, delivered via a fiber optic bundle, the switch turn-on was sustained for at least 200 ns, which is the pulse width of the Pulse Forming Line (PFL).