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The phase transition and optical properties of Cr2+-doped ZnSe under high pressure
摘要： The phase transition pressure, electronic structure, optical properties and stability for ZnSe and Cr2+:ZnSe with different doping concentrations were calculated by first-principles calculation based on density-functional theory. The phase transition pressure was calculated by enthalpy-pressure relation. The introduction of dopant (Cr2+) reduces the phase transition pressure, and the phase transition pressure decreases with the increase of doping concentration. The high pressure enhances the degeneracy of Cr-d orbitals. Under the high-pressure conditions, the absorption peak positions of Cr2+:ZnSe have obvious blue-shift. Meanwhile, the stability of structures for ZnSe and Cr2+:ZnSe were further confirmed by defect formation energy and elastic constants.
关键词： Phase transition pressure,Cr2+:ZnSe,First-principles calculation,Optical properties
更新于2025-09-23 15:22:29
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All-fiber passively Q-switched erbium-doped laser with Cr <sup>2+</sup> :ZnSe nanocrystals saturable absorber
摘要： We experimentally demonstrate an all-fiber Q-switched erbium-doped laser using polyvinyl alcohol-based Cr2+:ZnSe nanocrystals (NCs) as saturable absorbers (SAs). The Cr2+:ZnSe NCs were produced by femtosecond laser ablation, and were spherical, with an average radius of about 107 nm. The nonlinear saturable absorption was characterized with a saturable optical intensity of 20 MW cm?2 and a modulation depth of ～24%. By placing the SA inside an erbium-doped fiber (EDF) laser cavity, a stable 3.152 μs pulse with a repetition rate of 34.452 kHz centered at 1564 nm was achieved, when pumped at the maximum pumping power of 300 mW. The maximum pulse energy reached 33 nJ and the signal-to-noise ratio was 48 dB. The results indicate that Cr2+:ZnSe NCs are promising for the development of a stable all-fiber passively Q-switched EDF laser.
关键词： Cr2+: ZnSe nanocrystals,passively Q-switched,all-fiber laser
更新于2025-09-23 15:21:01