Enhanced emission of 286 μm from diode-pumped Ho^3+/Yb^3+-codoped PbF_2 crystal

Abstract

A novel Ho(3+)Yb(3+)-codoped PbF(2) mid-IR laser crystal was successfully grown and analyzed. Enhanced emission at 2.86 μm was observed from the crystal under excitation of a common 970 nm laser diode for the first time. The effect of Yb(3+) codoping on the 2.86 μm photoluminescence of Ho(3+) was investigated. In comparison to Ho(3+)-singly doped PbF(2) crystal, the Ho(3+)/Yb(3+)-codoped PbF(2) crystal possessed comparable quantum efficiency (88.8%), and fluorescence branching ratio (20.52%) along with a larger calculated emission cross section (1.90×10(-20) cm(2)) corresponding to the laser transition (5)I(6)→(5)I(7) of Ho(3+). It was found that the introduced Yb(3+) enhanced the 2.86 μm emission by depopulating the Ho(3+):(5)I(7) level. The energy transfer (ET) efficiency from Yb(3+):(2)F(5/2) to Ho(3+):(5)I(6) is as high as 96.7%, indicating that Yb(3+) ion is an effective sensitizer for Ho(3+) ion in PbF(2) crystal. These results suggest that Ho(3+)/Yb(3+)-codoped PbF(2) crystal may become an attractive host for developing solid state lasers at around 2.86 μm under a conventional 970 nm LD pump.

2.8 μm emission and OH quenching analysis in Ho3+ doped fluorotellurite-germanate glasses sensitized by Yb3+ and Er3+

“…Thus, the values of W OH for different OH − concentration can be calculated and showed in Table 3. The maximum quantum efficiency ( η ) of the 5 I 6  →  5 I 7 transition of Ho 3+ ions in this fluorotellurite-germanate glass expressed aswhere A 21 is the spontaneous transition from levels 5 I 6 to 5 I 7 , A 20 is the spontaneous transition from levels 5 I 6 to 5 I 8 , which can be the measured by absorption spectra and Judd-Ofelt parameters theory 46 . All results are listed in Table 3.…”

“…In this case, the donor and the acceptor are all Ho 3+ ions, the absorption and emission section can be obtained via Füchtbauer-Ladenburg 44 , Mc-Cumber theory 45 and showed in Fig. 6(b): where λ is the wavelength, A rad is the spontaneous radiative transition probability, which can be measured by absorption spectra and Judd-Ofelt parameters theory 46 . I ( λ ) is the fluorescence spectra intensity, n and c represent the refractive index and the speed of light, respectively.…”

Focus issue introduction: Advanced Solid-State Lasers (ASSL) 2014

“…Zhang et al [13] grew a novel Ho 3+ /Yb 3+ -codoped PbF 2 mid-IR crystal. Enhanced emission at 2.86 μm ( 5 I 6 → 5 I 7 of Ho 3+ ) was observed from the crystal under excitation at 970 nm.…”

Growth, structure, and spectroscopic properties of a Cr3+, Tm3+, Ho3+, and Pr3+co-doped LuYAG single crystal for 2.9 μm laser

“…Therefore, it is very significant to investigate and find 2.911 μm laser crystals in order to obtain this special wavelength laser. It is well known that the Ho 3+ ions, which possess abundant energy levels [11][12][13], are natural candidates for realizing 2.8-3.1 μm lasers corresponding to the transition from the 5 I 6 to 5 I 7 level [14,15]. Nevertheless, two bottleneck effects restrict the conversion efficiency of the 2.8-3.1 μm Ho 3+ lasers.…”

“…It is well known that Ho 3+ ions, which possess abundant energy levels, [11][12][13] are natural candidates for realizing 2.8-3.1 μm lasers corresponding to the transition from the 5 I 6 to 5 I 7 level. 14,15 Nevertheless, two bottleneck effects restrict the conversion efficiency of 2.8-3.1 μm Ho 3+ lasers. One is the lack of suitable pumping sources because a commercial laser diode (LD) or flash lamp can't match well with the intrinsic absorption of Ho 3+ ions.…”