To reduce the size of a high-voltage semiconductor optically responsive switch, for example suitable to control the flow of ignition energy from an ignition coil (4) to a spark plug (ZK), a stack of disk or plate-shaped semiconductor chips (9) is formed with the major surfaces of the chips placed against each other and light responsive regions of the chips at the outer surface thereof to form an array of chips with a control surface (14). The light responsive regions (13) are large enough so that, at any position of the respective chips in the array, the can receive sufficient switching energy from a point source, such as a light emitting diode (17) (LED). Thus, a single LED can control all the semiconductor switching elements. Energy for operation of the LED can be obtained, directly, by connecting the LED across a capacitor (C) in series between the ignition coil (4) and the high-voltage semiconductor switch (2), with an additional opto-electronic switch (20, TH), controlled by a control circuit (16) therewith which, when rendered conductive by the control circuit, will cause the LED (17) to fire.