“…The difference in energy of pump photons and emitted photons, non-radiative recombination and absorption of pump light outside the active region produce heating of the gain mirrors that needs to be extracted by appropriate heat-spreading schemes. As in other types of gain mirrors, the heat generated in 1300 nm wafer-fused gain mirrors may be quite efficiently dissipated either via intra-cavity diamond heat-spreaders [6,7], or in the flip-chip (thin disc) heat dissipation scheme [8,9]. So far, the maximum output power levels of 1300 nm VECSELs reached 6.6 W using the intra-cavity diamond heat-dissipation configuration with a 300 µm pump spot [6] and, very recently, 6.1W with the flip-chip heat dissipation configuration with a 400 µm pump spot [9].…”