Abstract: A laser with microwave excitation includes a source of microwave radiation coupled to a microwave resonator. The resonator is configured such that the microwave radiation generates an oscillating electric-field perpendicular to the longitudinal axis of the resonator corresponding to the first longitudinal resonator mode standing wave pattern. An excitation cavity, housing at least one gas discharge conduit, is coupled to the microwave resonator along a major portion of the cavity's length. The excitation cavity is configured to be below cutoff.