Nanoparticle doping for improved Er-doped fiber lasers

Abstract

A nanoparticle (NP) doping technique was used for making erbium-doped fibers (EDFs) for high energy lasers. The nanoparticles were doped into the silica soot of preforms, which were drawn into fibers. The Er luminescence lifetimes of the NP-doped cores are longer than those of corresponding solution-doped silica, and substantially less Al is incorporated into the NP-doped cores. Optical-to-optical slope efficiencies of greater than 71% have been measured. Initial investigations of stimulated Brillouin scattering (SBS) have indicated that SBS suppression is achieved by NP doping, where we observed a low intrinsic Brillouin gain coefficient, of ~1× 10 -11 m/W and the Brillouin bandwidth was increased by 2.5x compared to fused silica.

Nanoparticle doping for high power fiber lasers at eye-safer wavelengths

“…Alternately, as is the focus here, the local environment, hence phonon energy, about the RE 3+ can be tailored by incorporating it within a suitable nanoparticle that is dispersed into the silica matrix thus achieving low loss and high strength from the silica host with the reduced phonon energy of the NP. This includes nanoparticle hosts such as LaF 3 [15][16][17][18]. Reported here are Er nanoparticle doping concentrations that are higher than previously reported.…”

“…Various Al and Er molarities in the precursor solutions were investigated with the aim of obtaining molar ratios of Al:Er in the range between 10:1 and 200:1. Here, the aluminum precursor molarity was kept constant at 0.05 M, and the erbium molarity was varied from 0.005 M -0.00025 M. Thus, our Al:Er 10:1 ratio is a high molarity erbium precursor with 200:1 being low molarity [15][16][17][18]. These Al:Er ratios will dictate the concentration of Er 3+ ions encapsulated in the aluminum oxide nanoparticles.…”

“…Although the ripening conditions obviously affect the nanoparticle size and morphology, it is important to note that any Al-oxide phase formed is able to equally encapsulate the erbium ions. Furthermore, the soot consolidation and preform collapse stages are at temperatures of 1700-2000 °C, so any oxide phases are converted to Er-doped Al 2 O 3 [15][16][17][18].…”

“…, as confirmed by EMPA. The drawn NP doped fibers possess low background losses, on the order of < 40 dB/km at 1300 nm, and, despite the NPs being formed using an aqueous process extremely low OH concentrations of ~0.3 ppm are obtained in the resultant fibers as measured from the second OH overtone band at 1380 nm [16,17].…”

Nanoparticle and Solution Doping for Efficient Holmium Fiber Lasers

“…Since this pioneering work, the nanoparticle-doping technique has been extensively developed and practically substituted solution doping for various applications [12]- [16]. Nowadays, nanoparticles are widely used in the preparation of active optical fibers doped with erbium [15], [17], terbium [18], europium [18], holmium [19] and thulium [20].…”