Wideband multiwavelength Brillouin fiber laser based on dual-mode AlGaInAs/InP microcavity lasers.

A multiwavelength Brillouin fiber laser (BFL) is demonstrated using a 1.55-µm AlGaInAs/InP microcavity laser as a seed source. The combination of a nonlinear fiber cavity and a feedback loop leads to multiwavelength generation with a channel spacing of double-Brillouin-frequency assisted by cavity-enhanced four-wave mixing. The amplified output of a dual-mode lasing square microcavity laser with a wavelength interval of 1.5 nm is applied as the pump source for the broadband multiwavelength generation. A wideband multiwavelength BFL covering from 1490 nm to 1590 nm is successfully generated at an optimized pump power of 25 dBm and a feedback power of -17.2dBm. The power stability of 0.82 dB over a 60 min duration of the multiwavelength BFL can satisfy the demands for the optical fiber sensing and microwave photonic systems.

[High efficiency and low threshold upconversion from IR to red for Er3+ and Tm3+ co-doped fluoride-oxide glass-ceramic].

In this paper, high efficiency and low threshold upconversion from IR to red is reported, for Er3+ and Tm3+ co-doped fluoride-oxide glass-ceramic under 978 nm LD excitation. The component of sample in experiment is 65GeO2-25NaF-8.5BaF2-1Er2O3-0.5 Tm2O3, and the prepared method is obtained. The upconversion emission spectra under 978 nm LD excitation is measured at room temperature. Analyzing it, we find that introduction of Tm3+ into Er3+ doped system preferentially quenches the green upconversion fluorescence from 4S3/2 level of Er3+ duo to the efficient cross-relaxation of 4I13/2-->4I15/2 (Er): 3H6-->3H4 (Tm) which can significantly reduce the upconversion efficiency from 4I13/2 level to the emitting 4S3/2 level, and the Tm3+ behaves as a good sensitizer of the red upconversion from the 4F9/2 level of Er3+ which is mainly populated by the cross-relaxation of 3H4-->3H6 (Tm): 4I11/2-->4F9/2 (Er). However, at low Er3+ concentration (2 mol%), it is impossible for strong red upconversion. X-ray analysis is done, there are lots of nanocrystallites in MFG glass-ceramic. So we think, this red upconversion is attributed to Er3+ enriched fluoride microcrystallites, which makes the cross-relaxation of 3H4-->3H6 (Tm): 4I11/2-->4F9/2 (Er) more effective, therefore their active optical properties may be optimised. In the end, the relationship between LD working current and intensity of upconversion luminescence is discussed, the results confirm that both red and green upconversion processes are consisted by two photons.

[Up-conversion luminescence in nanocrystalline zirconia co-doped with Yb3+ and Tm3+ ions].

Nanocrystalline zirconia co-doped with Yb3+ and Tm3+ ions was prepared by co-precipitation. Up-conversion luminescence of the samples doped with different Tm3+ concentrations was investigated under a 980 nm LD excitation. When x = 0.2 and 0.4, the luminescences of the two samples were mostly the same: strong blue up-conversion peaked at 474 nm and very weak red up-conversion were observed, corresponding to the transitions of 1G4 --> 3H6 and 1G4 --> 3F4 respectively. However, there was no luminescence of x = 1. Blue up-conversion luminescence of 0.2 mol% Tm3+-ions-doped nanocrystalline zirconia under different annealing temperatures was investigated. Blue up-conversion emission grew stronger with annealing temperature increasing. With pumping current increasing, blue up-conversion emission grew stronger too. By studying the sources of blue up-conversion, we concluded that it was three-photon process.