Measured power-current curves of 660nm AlGaInP-based oxide-confined vertical-cavity surface-ernitting lasers (VCSEL) are compared with calculated data by a cylindrical heat dissipation model to improve heat removal out of the device. Pulsed lasing operation of a 670 nm VCSEL at high temperatures is demonstrated. At + 120 degreesC heat sink temperature we exceeded 0.5 mW and at + 160 degreesC still 25 muW output power were achieved. (C) 2004 Elsevier B.V. All rights reserved.