High-power rod-type photonic crystal fiber laser

Abstract

We report on a novel ytterbium-doped fiber design that combines the advantages of rod and fiber gain media. The fiber design has outer dimensions of a rod laser, meaning a diameter in the range of a few millimeters and a length of just a few tens of centimeters, and includes two important waveguide structures, one for pump radiation and one for laser radiation. We obtained 120-W output power in single-mode beam quality from a 48-cm-long fiber cane that corresponds to an extracted power of 250 W/m. The fiber has significantly reduced nonlinearity, which therefore allows for scalability in the performance of a high-peak-power fiber laser and amplifier system.

Single-Mode Regime in Large-Mode-Area Rare-Earth-Doped Rod-Type PCFs

“…However, to highlight the differences arisen in the numerical results, it is very interesting to compare the overlap values of all the fibers, since this is an important figure of merit for the following discussion. Notice that the 35-µm fiber air-cladding is hexagonal [8], unlike the circular one of the two other rod-type PCFs considered here. The overlap with the doped core of the FM and of the first HOM at 1064 nm is shown in Fig.…”

“…A recent development is the manufacture of DC PCFs, called rod-type fibers, with the outer dimension of a rod laser, i.e., a diameter of few millimeters [8]. While the large outer diameter provides a reduction of macro-and microbend losses, the device retains the stability and the performances of a fiber laser.…”

“…An important issue for these LMA PCFs is still to keep the excellent quality of the output beam, first of all by proper fiber designs that can assure the single-mode propagation. In fact, even if single-mode lasing has been experimentally demonstrated for Yb-doped rod-type fibers [8], [9], numerical simulations have previously shown that the single-mode regime of all-silica PCFs is significantly reduced when a core region as large as in rod-type fibers is considered [10]. This paper aims to provide guidelines on geometry and refractive index distribution in order to allow manufacturers to fabricate LMA DC doped PCFs that are single-mode, or effectively single mode at the lasing wavelength of interest, strongly related to the rare-earth element added in the fiber core.…”

“…In particular, the first one has been already manufactured with a Yb-doped core, formed by removing seven air holes, a triangular lattice of the inner cladding characterized by d/Λ = 0.33 with Λ = 12 µm, and an hexagonal air-cladding [8], whereas the second one has been designed by scaling the 60-µm PCF previously studied, and fabricated only in a passive version [9]. The values of d and Λ have been scaled by a factor 1.666, whereas the ratio d/Λ has been unchanged, and the study has been performed at 1064 nm.…”

Ytterbium doped phosphate glass photonic crystal fiber laser

“…Additionally, due to the natural ease of scaling PCF structures, the LMA fibres lasers manu− facturing is possible [9]. In order to provide the high power solutions, using PCF seems to be more promising than in case of step−index fibre lasers [10].…”