Here FRtest is the failure rate during life test, Ea is an activation energy, Icoeff is the power coefficient, Itest is the current during life test condition and Iop the current during operating. Top and Test are the laser diode junction temperature under operating and life test condition, respectively. From single mode laser diode multi cell tests we extract a conservative power coefficient of 3 and assume a typical value of Ea = 0.45eV.