RESUMO
We have demonstrated a record-high 1.2â kW, all-fiber multicore amplifier using a six-core single-mode Yb-doped fiber and a multicore pump-signal combiner (PSC). The output power is limited by the pump power of 1.9â kW. We have developed double-clad six-core fibers and PSCs for this demonstration. Each of the six Yb-doped cores has a 17-µm mode-field diameter (MFD) with a trench index profile and is capable of kW-class operation. The potential power scaling to the 10-kW level in a single amplifier with high brightness should be feasible with advanced thermal management and coherent beam combination.
RESUMO
Operation of a cw thulium laser emitting at 816 nm has been demonstrated in bulk Tm:YLF with 46% slope efficiency. Prior cw demonstrations of this transition have been limited to ZBLAN fiber hosts and prior lasing in bulk crystalline host material has been limited to quasi-cw operation due to population trapping. Trapping at the 3F4 level was mitigated by co-lasing at 1876 nm. The co-lasing technique should be applicable to room-temperature operation and to power scaling of YLF and other crystal hosts.
RESUMO
We investigate high brightness pumping of a multi-kilowatt Yb fiber amplifier in a bi-directional pumping configuration. Each pump outputs 2 kW in a 200 µm, 0.2 NA multimode fiber. Gold-coated specialty gain fibers, with a 17 µm mode field diameter and a 5 dB/m pump absorption, have been developed. The maximum fiber amplifier output power is 3.1 kW, limited by multimode instability, with 90% O-O efficiency and M2<1.15. The fiber amplifier linewidth is 12 GHz.
RESUMO
Five 500 W fiber amplifiers were coherently combined using a diffractive optical element combiner, generating a 1.93 kW beam whose M(2)=1.1 beam quality exceeded that of the inputs. Combining efficiency near 90% at low powers degraded to 79% at full power owing to thermal expansion of the fiber tip array.
