“…High surface quality, low absorption, double‐side polished single‐crystal 4H‐SiC wafers (0.37 mm in thickness and diced into 5 × 5 mm 2 chips) are used as heatspreaders. Characterised with the two‐colour Z‐scan technique [11], our SiC wafer has a background absorption of 0.09 cm −1 at 1020 nm, and 0.25 cm −1 at 532 nm. At the wavelength of interest, SiC has comparable absorption with standard commercially‐available single‐crystal CVD diamond (0.10 cm −1 ), but is still higher than low absorption diamond (0.01 cm −1 ).…”