Abstract: A surface-emitting laser includes an output unit. The output unit has an oblong-shaped VCSEL (vertical-cavity surface-emitting laser) structure. The output unit operates in an oscillation state in which a current that is larger than the oscillation threshold value is injected. The output unit receives a coherent seed light via a coupling surface at one end of the VCSEL structure in the longitudinal direction thereof. The seed light thus received propagates as a slow light through the VCSEL structure in the longitudinal direction thereof while being reflected multiple times in the vertical direction within the VCSEL structure. An output light is extracted from the upper surface of the VCSEL structure.