Phase-locking of 19-core Yb3+ - doped optical fibre

Abstract

Abstract. The supermode generation in a multicore optical fibre laser can be realised by phase-locking of radiation inside of the fibre. The model proposed by authors implies the achievement of supermode generation by exchanging radiation between the cores during the development of the laser action. The analysis of the impact of coupling value between the cores on phase radiation of particular emitters was considered. In the paper the phase-locking of 19-core optical fibre doped with Yb 3+ ions is presented. The analysis of material and geometrical parameters of the active 19 -core optical fibre and phase deviation on the beam quality factor of the laser beam in the far-field diffraction region has been analysed. The beam quality factor of the manufactured multicore fibre equals BQF = 0.71, V = 2.4, d = 18 µm. As a result of the conducted analysis a double-clad 19 -cores optical fibre doped with ytterbium ions has been designed and fabricated and its luminescence spectra and far-field diffraction pattern have been measured. Registered in the experiment in MOFPA system far-field pattern showed centrally located peak of relatively high radiation intensity together with smaller side-lobes, and as such was similar to the pattern which had been obtained numerically.

Novel constructions of optical fibers doped with rare – earth ions

“…Double-clad multicore optical fibers offer new possibilities in constructing of high-power short-length fiber lasers [31][32][33][34][35]. The main advantage is higher concentration of embedded rare earth ions than in typical single-core fibers which is proportional to the number of cores.…”

“…If the condition of coherent radiation generated in individual cores is fulfilled, then in the far -field diffraction pattern a centrally located peak of high intensity and low divergence (i.e. supermode) would be obtained, along with symmetrically placed side-lobes of significantly lower intensity [35]. Furthermore, angular divergence of the central peak decreases proportionally to the number of emitters (i.e.…”

“…In this construction, the amount of doped rare -earth element ions is higher than in typical single core fibers, which is proportional to the number of cores. Moreover, multiple cores in fiber cladding reduce the length of the fiber which is necessary to absorb the pumping radiation [17][18][19]. The second way to enhance the emission of an active optical fiber could be active optical fibers with the helical eccentrically located active core.…”

“…It should be characterized by: high selectivity, good beam quality of highpower density fiber toward directs optical fibers doped with rare-earth ions sources of radiation. Visible light sources, either in the form of laser or broadband source, relies on IR to VIS upconversion mechanism [18,19]. The Yb 3+ /RE systems are especially interesting because they can be pumped directly by a commercial laser diode (976 nm) [23][24][25][26].…”

Active optical fibres for application in laser and broadband ASE sources

“…Employing Dexter-Förster [22,23] semi-empirical model, maximum efficiency of energy transfer was calculated; for silicate glasses, its value was equal η ET = 61%, while for fluorophosphates glasses η ET = 65%. The devised glass compositions constituted the basis for production of multicore double-clad optical fibres [24,25]. Obviously, in fibres of this kind, the amount of doping rare earth ions is higher than in single-core fibres which makes it possible to reduce length of the fibre necessary to absorb pumping radiation.…”