Yb-free, SLM EDFA: comparison of 980-, 1470- and 1530-nm excitation for the core- and clad-pumping

High-Power Fiber Lasers

“…The approach is considered to be a power-scalable, eye-safe, highly efficient alternative to existing high-power Yb 3+ fiber lasers in the 1-lm range of the optical spectrum). Dubinskii et al [25] implemented the highpower cladding-pumped Yb 3+ -free Er 3+ amplifier system resonantly pumped at 1,480 and 1,530 nm, as shown in Fig. 10.21.…”

“…10.21. The authors [25] designed a singlefrequency Er 3+ fiber laser using a single-frequency diode laser as a MO, one preamplifier, and a high-power cladding-pumped amplifier. Using a Liekki Er 3+ -doped 20/125 LMA gain fiber in a booster stage, the authors achieved 46 % slope efficiency versus absorbed power when cladding pumped with 1,520-1,530-nm fiber-coupled laser diodes, as well as more than 9 W of CW optical power with diffraction-limited beam quality at a 1,570-nm wavelength.…”

Highly efficient Yb-free Er-La-Al doped ultra-low Na large mode area single-trench fiber laser

“…Recently, the output power level of Yb-free Er doped fibers has been scaled up to 75W by pumping at ~975nm and using reduced core to clad diameter, a 42% slope efficiency with respect to absorbed pump power at 975nm was also reported [4][5][6][7]. However, reported core diameter of fibers is smaller than 36µm to ensure effective single mode operation (ESM), which can restrict peak power scaling in pulsed operation [4][5][6][7]. Jasapara et al have demonstrated a 70µm core diameter multi-moded step index fiber (SIF) for peak power scaling achieving an effective area (A eff ) of 1,760µm…”

“…Moreover, presence of ytterbium and phosphorous increases the refractive index of the core and precludes the achievement of large mode area (LMA) required to address non-linear effects [2]. One solution to this problem is to use Yb free Er-doped fiber with resonant pumping near ~1480nm, which can be useful to generate high peak power pulses with moderate average output power due to the unavailability of high power pump diodes [3,4]. Moreover, pumping at ~1480nm leads to an overall poor electrical to optical efficiency.…”