All-intracavity fourth harmonic generation in a passively mode locked VECSEL for ultrafast UV emission

Abstract We demonstrate all-intracavity fourth harmonic generation in an ultrafast passively mode locked vertical external cavity surface emitting laser (VECSEL). This novel laser cavity design utilizes a high Q Z-cavity resonator to buildup the circulating power of the second harmonic for frequency quadrupling the fundamental 1060 nm to 265 nm. The demonstrated UV output has an average power of 525 μ W, pulse width of 3 ps, and a repetition rate of 510 MHz. This results in a peak pulse power of 250–300 mW over a 30 min duration without active stabilization equipment.