In this paper, we report the use of a 3-meter low-loss anti-resonant hollow-core fiber (AR-HCF) to deliver up to 300 W continuous-wave laser power at 1080 nm wavelength from a commercial fiber laser source. A near-diffraction-limited beam is measured at the output of the AR-HCF and no damage to the uncooled AR-HCF is observed for several hours of laser delivery operation. The limit of AR-HCF coupling efficiency and laser-induced thermal effects that were observed in our experiment are also discussed.

We investigated the ~2 μm spectroscopic and lasing performance of Tm³⁺ and Tm³⁺-Ho³⁺ co-doped tungsten tellurite glass single mode fibers with a commercial 800 nm laser diode. The double cladding single mode (SM) fibers were fabricated by using rod-in-tube method. The propagation loss of the fiber was ~2.5 dB/m at 1310 nm. The spectroscopic properties of the fibers were analyzed. A 494 mW laser operating at ~1.9 μm was achieved in a Tm³⁺ doped 20 cm long fiber, the slope efficiency was 26%, and the laser beam quality factor M² was 1.09. A 35 mW ~2.1 μm laser output was also demonstrated in a 7 cm long of Tm³⁺-Ho³⁺ co-doped tungsten tellurite SM fiber.

Large aperture Nd:phosphate laser glass is a key optical element for an inertial confinement fusion (ICF) facility. N31, one type of neodymium doped phosphate glasses, was developed for high peak power laser facility applications in China. The composition and main properties of N31 glass are given, together with those of LHG-8, LG-770, and KGSS-0180 Nd:phosphate laser glasses, from Hoya and Schott, and from Russia. The technologies of pot melting, continuous melting, and edge cladding of large size N31 phosphate laser glass are briefly described. The small signal gain profiles of N31 glass slabs from both pot melting and continuous melting at various values of the pumping energy of the xenon lamp are presented. N31 glass is characterized by a stimulated emission cross section of at 1053 nm, an absorption coefficient of 0.10–0.15% at laser wavelength, small residual stress around the interface between the cladding glass and the laser glass, optical homogeneity of 2 in a 400 mm aperture, and laser damage threshold larger than for a 3 ns pulse width at 1064 nm wavelength.

Lasers at ∼900nm have been of vital importance in various fields, including material processing, underwater communications, and strong-field physics. Although Nd³⁺-doped materials have been employed for the ∼900nm laser, the ∼900nm emission is in strong competition with the often more dominating ∼1060nm emission, which strongly limits the output power and applications. This paper proposes a direct coordination engineering approach, which introduces halogen to the nearest coordination of Nd³⁺ in glass for increasing the bond covalency, leading to stronger emissions at ∼900nm than at ∼1060nm. Iodide-incorporated Nd³⁺-doped silica fibers show prevailing ∼900nm emission rarely observed in Nd³⁺-doped materials. Using the created fibers, a power (113.5 W) 50 times higher than the current record is accomplished based on an all-fiber structure. Our approach holds the potential for regulating the spectroscopic properties of other rare-earth-doped laser materials.