Intense 27 μm and broadband 20 μm emission from diode-pumped Er^3+/Tm^3+/Ho^3+-doped fluorophosphate glass

Abstract

This Letter reports intense emission at 2:7 μm and broadband emission at 2:0 μm from Er 3þ =Tm 3þ =Ho 3þ -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 3þ and Ho 3þ 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 Recently, the development of mid-IR diode-pumped solid state lasers has been an area of great interest due to their various useful applications including military, remote sensing, eye-safe laser radar, and medical surgery [1,2]. Er 3þ -doped glass is well suited for the above applications owing to its 2:7 μm emission, which is close to the most pronounced absorption band of water at 3 μm. However, the laser characteristics of 2:7 μm due to the 4 I 11=2 → 4 I 13=2 transition are rather poor. The intrinsic difficulty to obtain laser action on this transition is mainly related to shorter fluorescence lifetime of the upper laser level 4 I 11=2 than that of the lower laser level 4 I 13=2 [3,4]. To obtain intense 2:7 μm emission, the artificial depletion of the 4 I 13=2 level is required, which can be achieved by suitable codoping of rare-earth ions and utilizing the energy transfer between levels of the respective ions having equal or close energies [5]. It has been reported that Tm 3þ ions can deplete the Er 3þ : 4 I 13=2 level to obtain 2:7 μm emission in GeGaAsS glass using a titanium-sapphire tunable laser as an excitation source, which can be attributed to the energy transfer between the Tm 3þ : 3 F 4 and Er 3þ : 4 I 13=2 levels [4]. As is shown in Fig. 1 Additionally, Ho 3þ lasers are also well suited for mid-IR range-finding, atmospheric monitoring, and sensing applications because their 2:0 μm emissions are within an atmospheric transparency window [6,7]. To enhance pump absorption, Ho 3þ -doped glasses have been sensitized with either Tm 3þ , Yb 3þ , or Er 3þ [8,9]. Nevertheless, there are few reports about the 2:0 μm emission in Er 3þ =Tm 3þ =Ho 3þ -doped glass [10].In order to get powerful mid-IR emissions from Er 3þ =Tm 3þ =Ho 3þ -doped glass, the host glass is as important as the choice of rare-earth ions. Regarding the emission at 2:7 μm, most research has focused on Er 3þ -doped fluoride and chalcogenide glasses [11][12][13]. Fluorophosphate (FP) glasses combine significant advantages of the fluoride and phosphate glass, and own a less complex fabrication route than that of fluoride and chalcogenide glasses [14]. They are characterized by good moisture resistance, high solubility for rare-earth ions, and broad absorption and emission bands [15,16]. In particular, FP glasses appear interesting for high power solid state lasers due to their low nonlinear refractive index, which will minimize associated phenomena such as self-focusing and self-phase modulation in high power lasers and ensure the highest possible laser i...

Mid‐IR to Visible Photoluminescence, Dielectric, and Ferroelectric Properties of Er‐Doped KNLN Ceramics

“…8 Er-doped materials have also been widely investigated for down-conversion PL, especially mid-infrared (MIR) emission. 6 The selection of host material plays an important role in achieving high efficiency of Vis up-conversion as well as MIR emission for Er 3+ . 4 I 11/2 ) matches well with the emission band of the readily available low-cost high-power diode lasers (980 nm).…”

“…Among the lanthanide ions, Er 3+ has been considered as one of the most popular and efficient activators for obtaining up-conversion PL because of the strong absorption bands available as pumping sources. 6,7 The efficiency of up-conversion also depends on the dopant concentration, energy migration between activators, distribution, and site symmetry of activators in the host as well as the host geometry. 8 Er-doped materials have also been widely investigated for down-conversion PL, especially mid-infrared (MIR) emission.…”

Ho3+/Yb3+-codoped germanate–tellurite glasses for 20 μm emission performance

“…Moreover, codoping another energy acceptor, syntonic, except Yb 3 , like a tridoped system, is an alternative method. Recently, our team also reported numerous tridoped glass materials to investigate 2.0 μm emission [23][24][25][26]. Our future research includes investigating rare-earth ions in triple-doped GT glass systems.…”

Effect of gallium environment on infrared emission in Er3+-doped gallium– antimony– sulfur glasses

“…The fiber lasers operating at mid-infrared (MIR) wavelength can be obtained from various RE lasing ions, such as Dy 3+ , Ho 3+ , Pr 3+ , Tm 3+ , and Er 3+  567. Among them, Er-doped glasses are attractive for use in integrated optoelectronics because of the Er 3+ intra-4f emissions at the standard telecommunications wavelength at 1540 nm8910.…”