High power 980 nm pump lasers

Higher power pump lasers will be used in future designs of erbium doped fiber amplifiers (EDFAs) to reduce the number of components in the EDFA as well as increase the channel count capacity of the fiber. The usable power from the laser is limited by the linear response of the optical power as a function of laser current (L-I curve). For 980 nm lasers, the "kink" level limits the useful operating power rather than rollover of the L-I. The origin of the kink has been attributed to lateral mode changes in the laser as a function of current. To increase the kink power of a laser, it is therefore reasonable to investigate ways of reducing the carrier density and heat generation in the laser cavity. We have studied the effect of increasing the cavity length of the laser chip on the device performance. Longer cavity lasers have reduced current density at a given output power, but at the cost of an increase in the threshold current and decrease in the slope efficiency. The laser structure investigated was a ridge waveguide InGaAs-AlGaAs SQW GRINSCH.