Abstract: A safety interlocking arrangement for use with a doped fiber amplifier and its associated pump source(s). A pair of metallized jumper cables are used to interconnect the amplifier and pump source, where the physically connections to the housings are electrically isolated. Within the pump source, an isolated power supply, in series with a control switch (such as an optical coupler) is connected between the isolated fiber coupling ports. Within the doped fiber amplifier, a diode is connected between the isolated amplifier fiber coupling ports. When the metallized jumper fiber cables are properly connected between the pump source and the amplifier, the electrical circuit is completed and a low level current will flow. The current activates the control switch within the pump source, where the control switch functions to turn "on" the pump source lasers. If either metallized jumper fiber is misconnected, broken or missing, no current will flow.