Abstract: A method of passively enhancing pulsed laser light by coherent addition of laser pulses in an enhancement cavity (20) comprises the steps of generating a sequence of seed laser pulses (1) with a repetition frequency frep and a frequency comb spectrum (3) comprising frequency comb lines (4) with frequency comb line spacings equal to the repetition frequency frep, coupling the seed laser pulses (1) via a first plate-shaped coupling element (25) into an enhancement cavity (20) comprising at least two cavity mirrors (21, 22, 23, 24) having metallic surfaces and spanning a cavity beam path (26) with a resonator length L, wherein the enhancement cavity (20) has a fundamental transverse mode TEM00 and higher-order transverse cavity modes TEMnm, each with a series of cavity resonance frequencies (5), and a cavity offset frequency (6), and coherent superposition of the seed laser pulses (1) in the enhancement cavity (20), so that at least one enhanced circulating cavity pulse (2) per cavity length is generated, wherei