US Patent 10211591 Tandem pumped fiber amplifier

In an example, a tandem pumped fiber amplifier may include a seed laser, one or more diode pumps, and a plural core fiber including a first core and a second core, the second core surrounding the first core. The plural core fiber may include a first section to operate as an oscillator and a second different section to operate as a power amplifier. The one or more diode pumps may be optically coupled to the first section of the plural core fiber, and the seed laser may be optically coupled to the first core.