Reaching 1 Watt Reliable Output Power on Single-Mode 980 nm Pump Lasers

Single-mode 980 nm pump lasers are mature products needed in an increasing range of applications and their power level has been constantly raised in the last fifteen years from a few tens of mW for the first generations of devices up to the current maximum level of 750 mW fiber-coupled output power. As the fiber output power increases, new applications provide positive feed-back to continue the development of these devices, although severe constraints are imposed both by reliability and the need for wavelength stabilization, which is generally built on the utilization of Fiber Bragg Gratings (FBGs). We have developed in 2005 a record saturation power device [1] (P-sat=2.35W @ 25 degrees C, for 3.9 mm cavity lengths) whose fiber-coupled power has reached 750 mW for 25 C cooled applications, limited mainly by reliability as wavelength stabilization was already demonstrated up to levels above 1 Watt. 3S PHOTONICS has now developed a new generation of powerful and reliable devices that allow foreseeing operation at or close to 1W for cooled applications. We have further optimized the vertical structure to reduce the internal losses, and to reduce the junction temperature for increased reliability. High kink-currents around 2.5 A have been measured on the best devices. The gain bandwidth has been engineered to allow maintaining the wavelength stabilization even on very long laser cavities. Encouraging preliminary reliability results have also been obtained.