The lifetime of high-power (430-460 mW, lambda-0.98 mu m) heterolasers
was investigated at T = 70 degrees C. Slow degradation as well as sud
den failure, characterised by a lognormal distribution, were observed.
A statistical calculation was made of the maximum lifetime of heterol
asers: it was found to be 5430 h at 70 degrees C for a pump current of
1 A.