nics systems, high-power durable pump lasers are equally instrumental to realize optical amplifiers. The success of fiber amplifiers, both based on erbium-doped fibers and Raman effect, is largely due to the availability of high-power laser diodes at suitable pump wavelengths. Considering laser diodes designed to pump optical amplifiers, the key performances to care for are the emitted power, the stability of the wavelength, and the ability to emit a mode that can be focused easily on the small spot represented by a fiber-optic core. Reliability is also a key property of these lasers, due to the fact that the reliability of the whole amplifier is largely determined by the reliability of the pumps. The lifetime of semiconductor lasers decreases more than linearly, increasing the aver- age emitted power, due to the fact that the more photons are present inside the laser cavity, the faster is the growth of fabrication micro-defects up to a state where they thwart the laser working. Thus a major challenge for the manufacturers of pump lasers is to assure a long lifetime without scarifying the emitted power. Another key design point for this type of lasers is the power consumption, which has to be limited as much as possible. For this reason, it is important to have a high number of degrees of freedom in designing pump lasers, a condition that is assured by the use of not only a carefully selected alloy of III-V semiconductors for each laser section, but also a strained multi-quantum well (MQW) structure in the active zone. In this way, the emitted wavelength is determined mainly by the MQW and the threshold current can be reduced allowing the emission of the required power at a lower bias current. Moreover, in order to maintain the structure as simple as possible and avoid local micro-defects due to complex fabrication processes, almost all the pump lasers have an FP structure. Since the emission wavelength is determined by the MQW structure, the base laser material can be selected to assure stability and reliability