Optically triggered UV sensitive receivers were fabricated on polycrystalline diamond as surface channel MESFETs. Opaque gates with asymmetric structure were designed in order to improve charge photogeneration mainly within the gate-drain region. Photogenerated holes contributed to the channel charge by assistance of the local electric field, in such a way improving the current signal at the drain contact. The sensitivity to UV light is demonstrated by using 3 ns wide laser pulses at 193 nm, well over the diamond bandgap. The receiver transient response to such laser pulses shows that the photogeneration process is only limited by the pulse rise time and charge collection at the drain contact completed in a time scale of a few nanoseconds. Such opaque gate three-terminal devices are suitable for application in emerging photonic technologies, for power-management system optical receivers, where copper wires and EM shielding can be replaced by lightweight optical fibers.