Raman microprobe studies of AlGalnP 670 nm lasers show a higher facet temperature rise per unit output power than that observed in AlGaAs lasers. This heating appears to be localised in the lasing region of the laser facet. These results are supported by probe beam facet heating experiments which show substantial differences between the AIGalnP and AlGaAs lasers. © 1992 The Institution of Electrical Engineers. All rights reserved.