solid-state maser

solid-state maser [′säl·əd ¦stāt ′mā·zər]

(physics)

A maser in which a semiconductor material produces the coherent output beam; two input waves are required: one wave, called the pumping source, induces upward energy transitions in the active material, and the second wave, of lower frequency, causes downward transitions and undergoes amplification as it absorbs photons from the active material.