Exploring the power scaling of the cryogenic 946 nm monolithic laser

The criterion for achieving power scaling of the cryogenically cooled monolithic 946 nm laser is investigated by varying crystal length. Theoretical analysis of the mode-to-pump size matching indicates that the optimal power can be obtained with a crystal length of 8 mm. Furthermore, the pump-wavelength dependence of the output power can be less sensitive when a longer crystal was employed. We demonstrate 946 nm monolithic lasers with various crystal lengths to verify the theoretical analysis. The highest output power (30.2 W) is obtained by using an 8 mm Nd:YAG crystal at 130 K. Moreover, the output power reduction ratio is found to be smaller than 15% with the pump wavelength fluctuating between ±1 nm.