Fast–Slow Red Upconversion Fluorescence Modulation from Ho³⁺‐Doped Glass Ceramics upon Two‐Wavelength Excitation

Abstract

indispensable, which is ubiquitous in photo nics and optoelectronics applications, such as optical interconnect, environmental monitoring, biosensing, medicine, secu rity, astronomical, and allfibertohome applications. [2,3] Unlike electrons, photons interact weakly with each other. [4] Therefore, an optical modulation requires the media tion of a physical system to produce effi cient photon-photon interactions. Dif ferent approaches to optical modulators have been proposed, often based on fast and highly nonlinear media that would enable alloptical switch devices, including 2D layered materials, [5] high nonlinear responses materials with wellengineered structures, [6] and optomechanical and phasechange metamaterials. [7] However, to our best knowledge, there is no any report about utilizing rare earth (RE) ions to realize fastslow optical modulation. [8,9] Theoretically, it is expected to develop a versatile physical strategy to realize fast slow optical modulation of upconversion (UC) fluorescence from RE ions, which can be tailored by simultaneous twowave length excitation. Among various RE ions, [10][11][12] owing to abun dant energy levels of Ho 3+ ions, it is convenient for us to realize fastslow optical modulation of red UC fluorescence from Ho 3+ ions by simultaneous twowavelength excitation at 1.0 and 2.0 µm lasers. What's more, tunable excitation and emission wavelengths are operating at nearinfrared (NIR) window or atThe control of one light field by another, ultimately at manipulating efficiently photon-photon interactions obsoleting traditional electronic interconnection approach, is an attractive area of research in the development of alloptical network information science. Herein, an exquisite physical strategy is introduced to realize fast-slow optical modulation of red upconversion (UC) fluorescence from Ho 3+ :LaF 3 nanocrystals embedded glass ceramics (GCs) tailoring by simultaneous two-wavelength excitation at 980 and 1870 nm laser. An optical modulation of more than 2500% of the red UC fluorescence intensity and a fast response with rise time of 230 µs and decay time of 66 µs as well as a slow response with rise time of 23 ms and decay time of 6.65 ms in the red UC fluorescence signal is shown. The dynamic evolution analysis and theoretical simulations suggest that this fast-slow optical modulation of red UC fluorescence is rooting from the presence of differentiation of the speed of electrons fully populated in the excited-state 5 I 7 regulated by various pumping tactics. The fast-slow optical modulation of red UC fluorescence from Ho 3+ -doped GCs, manipulating through two-wavelength excitation at 980 and 1870 nm laser, may find novel application in future all-optical fiber data processing in various optoelectronic fields.

Tailorable Upconversion White Light Emission from Pr3+ Single‐Doped Glass Ceramics via Simultaneous Dual‐Lasers Excitation

“…Conversely, much longer lifetimes at the corresponding UC fluorescence signals for various samples have obtained when tuning the 980 nm laser beam as gating signal and simultaneously adding a CW 850 nm laser beam (Figure b and Figure S6d–f, Supporting Information). This phenomenon is similar to our previous observations, which is mainly induced by the differentiation of electrons population speed in the intermediate excited state 1 G 4 of Pr 3+ manipulated by various pumping strategy. When tailoring 980 nm laser as CW beam and simultaneously combing a gating beam of 850 nm laser (as shown in Figure a and Figure S6a–c, Supporting Information), electronic state from the ground state 3 H 4 level to the first excited level 1 G 4 can be considered as steady state, so less time is required to reach to the steady state, but electrons transition from the 1 G 4 level to the 3 P or 1 I 6 level are extremely less, and the rate of spontaneous emission from the 5 F 5 level to the 5 I 7 and 5 I 8 level are relatively fast, which leads to a shorter fluorescence lifetime.…”

“…To shed more light on the microscopic mechanism of this dual‐wavelength pumping approach, we studied the dependence of the UC fluorescence intensities at 486, 522, and 600 nm on the laser power. The number of photons required for the fluorescence yield can be obtained from the formula: I em ∝ P n , where I em is the emission intensity, P is the pump laser power, and n is the number of laser photons . As plotted in Figure a–f, all data sets in the UC fluorescence are represented well by an apparently linearity fitted relationship.…”

“…Fabrication of Samples : The fabrication of LaF 3 :Pr 3+ nanocrystals embedded germanate oxyfluoride GCs is similar to our previous works . The precursor glasses, with a composition of 50GeO 2 ‐22Al 2 O 3 ‐13LaF 3 ‐15LiF‐ x PrF 3 ( x = 0.01, 0.05, 0.1, 0.5, 1, mol%), were melted at 1450 °C for 1 h. The precursor glasses were cut into blocks and then heat treated at 680 °C for 4 h to obtain GCs through crystallization.…”

“…Hence, it is necessary to study the UC white light modulation performances of Pr 3+ single‐doped germanium oxyfluoride GCs for the improvement of future white light GCs fiber lasers. More importantly, in comparison with single laser excitation, simultaneous dual‐lasers excitation shows many unique advantages for UC photoluminescence, for example: UC luminescence efficiency is much higher, novel UC luminescence phenomena are easy to be stimulated, and etc . However, to the best of our knowledge, there is no any literatures on introducing this simultaneous dual‐lasers pumping strategy to achieve highly efficient and tunable UC white light emission (WLE) for the development of future white light GCs fiber lasers until now.…”

Novel Er3+/Ho3+‐codoped glass‐ceramic fibers for broadband tunable mid‐infrared fiber lasers

“…Combining the advantages of the low phonon energy of fluoride nanocrystals and the outstanding chemical durability and thermal stability of the oxide glass matrix, oxyfluoride glass-ceramics (GCs) have been considered as potential candidates for rare-earth-doped fiber lasers. [12][13][14][15][16] However, regretfully, there is neither report on the fabrication of Er 3+ /Ho 3+ -codoped oxyfluoride GC fibers, nor the investigation of broadband tunable MIR spectroscopic properties of these fibers to our best knowledge. If so, the application of the fiber in MIR fiber lasers will be seriously limited.…”