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The structural origin and laser performance of thulium-doped germanate glasses have been studied. The investigation includes two main sections. The first part discusses the Raman spectroscopic and thermal stability of the host glass structure. The low value of the largest phonon energy (850 cm(-1)) reduces the probability of nonradiative relaxation. The large emission cross section of the Tm(3+) : (3)F(4) level (8.69 × 10(-21) cm(2)), the high quantum efficiency of the (3)F(4) level (71%), and the low nonradiative relaxation rate of the (3)F(4) → (3)H(6) transition (0.09 ms(-1)) illustrate good optical properties of the germanate glass. In the second part, the room-temperature laser action from the thulium-doped germanate glass is demonstrated when pumped by a 790 nm laser diode. The maximum output power of 346 mW and slope efficiency of 25.6% are achieved.

This Letter reports intense emission at 2.7 μm and broadband emission at 2.0 μm from Er(3+)/Tm(3+)/Ho(3+)-doped fluorophosphate glass. The fluorescence characteristics and energy transfer upon excitation of a conventional 980 nm laser diode are investigated. Based on the fluorescence spectra and lifetime measurement, the effect of Tm(3+) and Ho(3+) ions on intense 2.7 μm emission in fluorophosphate glass is demonstrated. It is also found that the effective bandwidth of 2.0 μm emission due to Tm(3+) and Ho(3+) ions can reach as high as 196 nm. These results indicate that the advantageous spectroscopic characteristics of Er(3+)/Tm(3+)/Ho(3+) triply doped fluorophosphate glass together with the outstanding thermal properties may become an attractive host for the mid-IR solid state lasers., (© 2011 Optical Society of America)

A novel Er(3+)/Pr(3+) codoped germanate glass was fabricated and analyzed. Efficient emission at 2.7 μm from the glass was observed upon excitation of a conventional 980 nm laser diode. The 2.7 μm emission characteristics and energy transfer (ET) were investigated. Population inversions between ⁴I(13/2) and ⁴I(11/2) levels have been achieved, and an enhanced emission from 2550 to 2800 nm was obtained. Large ET efficiency of 95% indicates that the ET process from Er(3+) to Pr(3+) (⁴I(13/2), ³H₄)→(⁴I(15/2), ³F₃) is efficient and that Pr(3+) can enhance the emission of 2.7 μm by quenching the lower laser level of Er(3+) via ET.

This work reports the intense emission at 2.7 μm in a Er(3+)/Pr(3+)-codoped fluorophosphate (FP) host glass. This FP glass shows good thermal stability and high transmittance around 3 μm. The emission characteristic and energy transfer upon excitation of a conventional 980 nm laser diode are investigated. The prepared glass possesses higher spontaneous transition probability (22.16s(-1)) along with a larger calculated emission cross section (6.57 ± 0.11) × 10(-21) cm(2) corresponding to the laser transition (4)I(11/2)→(4)I(13/2). In addition, the effect of Pr(3+) codoping on the 2.7 μm photoluminescence in FP glass is demonstrated. Hence, the advantageous spectroscopic characteristics of Er(3+)/Pr(3+)-codoped FP glass together with the outstanding thermal property indicate that this kind of glass may become an attractive host for developing solid-state lasers at around 2.7 μm.

2.7 μm emission properties and energy transfer mechanism of Nd3+/Er3+ co-doped sodium tellurite glasses are investigated in present paper. Absorption and emission spectra were tested to characterize the 2.7 μm emission properties of Nd3+/Er3+ co-doped sodium tellurite glasses and a reasonable energy transfer mechanism of 2.7 μm emission between Er3+ and Nd3+ ions was proposed. Intense 2.7 μm emission was obtained from Nd3+/Er3+ co-doped sodium tellurite glasses due to the efficient energy transfer from Nd3+ to Er3+ ions under 808 nm LD pumping. Meanwhile, strongly decreased 545 nm up-conversion and 1.5 μm emissions were observed. Additionally, to obtain efficient 2.7 μm emission, the optimized concentration ratio of Nd3+ to Er3+ was found to be 0.5:1 in present glass system. Our results suggest that the present Nd3+/Er3+ co-doped sodium tellurite glass might have potential application in mid-infrared lasers. [ABSTRACT FROM AUTHOR]

Abstract: Tm3+/Yb3+-codoped fluorophosphate glass is prepared by conventional melt-quenching method and the thermal stability of the glass is analyzed. The Judd–Ofelt parameters, radiation emission rates, radiative lifetime and branching ratios of prepared samples are calculated based on the absorption spectra. Upon excitation of a conventional 980nm laser diode, 1.8μm emission is obtained from Yb3+/Tm3+ codoped fluorophosphate. Additionally, the energy transfer between Yb3+ and Tm3+ ions are quantitatively analyzed. Hence, this Yb3+/Tm3+ codoped fluorophosphate glass possessing high energy transfer efficiency and excellent thermal stability is a good candidate for efficient 1.8μm laser. [Copyright &y& Elsevier]

Abstract: Fluorophosphate glasses co-doped with Dy3+ and Tm3+ ions have been synthesized with low OH content. Photoluminescence around 2.9μm is successfully obtained in present glass excited by a conventional 808nm laser diode. The luminescence characteristics and energy transfer mechanism are investigated. Based on the absorption, fluorescence spectra and lifetime measurements, Tm3+ ions can effectively absorb excitation energy and then play an important role in getting 2.9μm emission. Besides, it is found that Tm3+ ions can transfer their energy to Dy3+ ions with high efficiency. Hence, the results indicate that Dy3+/Tm3+ co-doped fluorophosphate glass possessing advantageous spectroscopic characteristics is a potential cost-effective host for the mid-infrared solid state lasers. [Copyright &y& Elsevier]