The characteristics of pump light in side-coupled cladding-pumped fibers

• A model taking both the absorbing and coupling coefficients into account was established.
• The propagation and absorption characteristics of pump light have been investigated in detail.
• The coupling process can reduce the pump light absorbing effect and distribute the thermal load.
• It needs bigger absorption coefficient and smaller coupling coefficient ratio k2/k1.
• It shows that DSCCP fiber can play an important role in the field of high-power fiber lasers.

The propagation and absorption characteristics of pump light in the side-coupled cladding-pumped active fiber were investigated. A model taking both the absorbing and coupling coefficients into account was established. It is revealed that the absorbing effect of the active fiber enhance the pump-light coupling from the passive fiber to the active fiber, while the coupling effect reduce the absorbing process compared to the common double-cladding fiber. The study also considers the effect of the coupling coefficient ratio. It is found that higher effective absorption coefficient requires bigger absorption coefficient and smaller coupling coefficient ratio.