Continuous-wave diamond Raman lasers (DRLs) operated at high pump power commonly suffer from power roll-off and output instability, even when high-thermal-conductivity gain media are employed.These degradations originate from thermally induced cavity-mode mismatch and cavity-length drift, which limit further power scaling.In this work, we establish a thermal-optical chain-linked model that quantitatively describes the coupled evolution of thermal deposition, equivalent thermal lensing, intracavity mode matching, and output power in high-power diamond Raman lasers, providing a direct physical link between pump power and cavity-length compensation.Based on this model, a Peak-Valley Co-location (PVC) criterion is proposed to determine the optimal cavity-length compensation point.Both theoretical and experimental results show that the output power exhibits a single-peak dependence on cavity-length offset, while the power stability follows a U-shaped distribution, and their extrema coincide at an optimal compensation value L*.By operating at L*, the maximum Stokes output power increases from 27 W to 32 W, and the RMS power fluctuation decreases from 4.8% to 3.2%.These results demonstrate that thermal-lens-induced performance degradation can be effectively mitigated by cavity-length compensation using a single control parameter, providing a practical design rule for simultaneous enhancement of output power and stability in high-power Raman laser systems.
Zhang et al. (Wed,) studied this question.