Why are fiber lasers more efficient than other solid state and gas lasers?

The answer is simple – the design of fiber lasers generates less heat and manages the heat they generate effectively. The quantum defect (that is the difference between pump and emission energy) is lesser for a Ytterbium diode-pumped fiber laser (pumped at 980 nm) than a Nd:YAG diode pumped laser (pumped at 808 nm). Also, the optical to optical conversion efficiency of fiber laser is typically 70-80%, as compared with approximately 4% for lamp pumped YAGs, and approximately 40% for diode-pumped YAGs and disk lasers. Because the light is always contained in a fiber, there are no additional sources of the loss inside the laser cavity.