Which factor determines the efficiency of a laser?

The efficiency of a laser is primarily determined by the ratio of output power to input power. This metric provides a clear understanding of how effectively the laser converts electrical or pump energy into laser light. A higher ratio indicates that a larger portion of the input energy is being transformed into useful laser output, which is critical for practical applications and overall performance.

In laser applications, the efficiency directly influences the operating cost, potential heat generation, and the overall design of laser systems. The other factors, while they play important roles in the overall functioning and performance of a laser, do not define its efficiency in terms of energy conversion as effectively as this ratio does.