A band pass filter includes a first electrode, a second electrode, and a plasma generated by the first and second electrode. The plasma is confined to a region of space through which electromagnetic waves having a frequency above an intrinsic plasma frequency are transmitted, and electromagnetic waves having a frequency below the intrinsic plasma frequency are reflected. The band pass filter may be implemented in a photo lithography tool between a source module and an exposure module. The plasma of the band pass filter may be adapted to reduce IR radiation (or other out of band radiation) exposure to the exposure module by reflecting IR radiation back to the radiation source. In an extreme ultraviolet photo lithography tool, the plasma of the band pass filter may be adapted to transmit EUV radiation.