Since the visible quantum cutting in Eu3+–Gd3+ material was reported, the importance, the application, and the significance of the quantum cutting phenomenon have been widely recognized.The rate equations which describe the luminescence dynamic processes for different concentrations of (ErxLa1-xP5O14) noncrystal are established in this paper. The coefficients exp{hc k/kT} is introduced in to the calculation of anti-Stokes energy transfer rate to distinguish Stokes energy transfer.All dynamic processes have been simulated separately with and without considering this coefficient for the energy transfer rate of Er0.01La0.99P5O14,Er0.1La0.9P5O14 and ErP5O14 noncrystals when their 2H11/2 ,4I9/2 and4I11/2 levels are excited.The results show that it is essential to take the coefficient into calculation particularly for ErP5O14 noncrystal where energy transfer plays a key role.There is no influence though the distance between rare earth ions is larger.And it is found that infrared quantum cutting exsists in ErP5O14 noncrystal excited by visible light. The relative nonradiative relaxation rate, the spontaneous emission rate and the energy transfer rate are calculated particularly , The relative energy transfer dynamics is analyzed.It is found that the {4H11/2→4I9/2,4I15/2→4I13/2} energy transfer with a rate of 239500s-1, is the main reason for 2H11/2 energy level to have the infrared quantum cutting, Which is meaningful for finding high-efficiency solar cell materials.

The improvement on the calculation of anti-Stokes energy transfer rate is studied in the present work. The additional proportion coefficient between Stokes and anti-Stokes light intensities of quantum Raman scattering theory as compared with the classical Raman theory is introduced to successfully describe the anti-Stokes energy transfer. The theoretical formula for the improvement on the calculation of anti-Stokes energy transfer rate is derived for the first time in this study. The correctness of introducing coefficient exp{ΔE/kT} from well-known Raman scatter theory is demonstrated also. Moreover, the experimental lifetime measurement in Er0.01YbxY1–0.01-x VO4 crystal is performed to justify the validity of our important improvement in the original phonon-assisted energy transfer theory for the first time.

We numerically simulate a photonics phenomenon of what we call intensity inversion between red and green fluorescence in oxyfluoride nanophase vitroceramics Er(1%)Yb(8%):FOV through the integration of whole fluorescence's theories. We found that it is essential to introduce a coefficient presenting the difference between the Stokes energy transfer and anti-Stokes energy transfer processes in nano-material when calculating the energy transfer rate. Under this consideration, and with the total crystallized volume ratio set to be 17.6%, the simulation results of the population probabilities values of all energy levels of Er3+ ion are coincident with the experimental result perfectly.

The dynamics of all levels were calculated numerically in the present article for Er(0.5)Yb(3):FOV oxyfluoride nanophase vitroceramics. The population dynamical processes were analyzed carefully. It was found for the first time that traditional phonon-assisted energy transfer theory of rare earth ion energy transfer can not well explain the observed experimental calibrated results, as it does not take into account the difference between Stokes and anti-Stokes process. A coefficient, the improved factor of the intensity ratio of Stokes to anti-Stokes process in quantum Raman theory compared to classical Raman theory, was introduced for the first time to successfully describe the anti-Stokes energy transfer. The theoretical improvement results are coincident with experiments very well. This improvement is very significant and indispensable when the photonics of nanomaterials is probed.

A photonic phenomenon of fluorescence intensity reverse between red and green fluorescence was studied theoretically and experimentally in the present article. It was found by experiment that Er(0.5)Yb(9.5) FOV : oxyfluoride vitroceramics exhibits strong fluorescence intensity reverse phenomenon. The range of the intensity reverse of Er(0.5) Yb(9.5) FOV : was measured to be 877. Moreover, all basic spectroscopic parameters were calculated. The theoretical basis of numerical calculation for dynamics processes of all levels was established.

The widely used energy transfer theory is a foundation of luminescence, in which the rates of Stokes and anti-Stokes processes have the same calculation formula. An improvement on the anti-Stokes energy transfer to explain the fluorescence intensity reversal between the red and green fluorescence of Er(0.5)Yb(9.5):FOV is reported in the present article. The range of the intensity reversal σ was measured to be 877. Dynamic processes for 16 levels were simulated. A coefficient, the improvement factor of the intensity ratio of Stokes to anti-Stokes processes in quantum Raman theory compared to classical Raman theory, is introduced to successfully describe the anti-Stokes energy transfer. A new method to calculate the distance between the rare earth ions, which is critical for the energy transfer calculation, is proposed. The validity of these important improvements is also proved by experiment.

The ultraviolet upconversion luminescence of Tm3+ ions sensitized by Yb3+ ions in oxyfluoride nanophase vitroceramics when excited by a 975 nm diode laser was studied. An ultraviolet upconversion luminescence line positioned at 363.6 nm was found. It was attributed to the fluorescence transition of 1D2→3H6 of Tm3+ ion. Several visible upconversion luminescence lines at 450.7 nm, (477.0 nm, 462.5 nm), 648.5 nm, (680.5 nm, 699.5 nm) and (777.2 nm, 800.7 nm) were also found, which result respectively from the fluorescence transitions of 1D2→3F4, 1G4→3H6, 1G4→3F4, 3F3→3H6 and 3H4→3H6 of Tm3+ ion. The careful measurement and analysis of the variation of upconversion luminescence intensity F as a function of the 975 nm pumping laser power P prove that the upconversion luminescence of 1D2 state is partly a five-photon upconversion luminescence, and the upconversion luminescence of 1G4 state and 3H4 state are respectively the three-photon and two-photon upconversion luminescence. The theoretical analysis suggested that the upconversion mechanism of the 363.6 nm 1D2→3H6 upconversion luminescence is partly the cross energy transfer of {3H4(Tm3+), 3F4(Tm3+), 1G4(Tm3+)→1D2(Tm3+)} and {1G4(Tm3+)→3F4(Tm3+), 3H4(Tm3+)→1D2(Tm3+)} between Tm3+ ions. In addition, the upconversion luminescence of 1G4 and 3H4 state results respectively from the sequential energy transfer {2F5/2(Yb3+)→2F7/2(Yb3+), 3H4(Tm3+)→1G4(Tm3+)} and {2F5/2(Yb3+) →2F7/2(Yb3+), 3F4(Tm3+)→3F2(Tm3+)} from Yb3+ ions to Tm3+ ions.

Ho3+ : GdVO4 is a new laser material suitable for high-power laser systems. In this paper we measure the absorption spectra of Ho3+ in the sample Ho3+: GdVO4. The intensity parameters are calculated by using the Judd–Ofelt theory. Some predicted spectroscopic parameters, such as the spontaneous radiative transition rate, branching ratio and integrated emission cross section are dealt with. And we also compare the optical parameters with those of other materials. From these results, it is found that there are many transitions which have large oscillator strengths and large integrated emission cross sections. Especially the transitions such as 5F4 → 5 I8, 5S2 → 5 I8,5F5 → 5 I8 and 5I7 →5 I8 are useful in solid-state lasers and other fields. Finally, we discuss the splitting of the energy levels of Ho3+ in the crystal GdVO4 based on the group theory.

Er3+: GdVO4 is a new laser material which is suitable for high-power laser systems. In this paper we firstly measured the absorption spectrums of Er3+ in the sample Er3+: GdVO4, then the intensity parameters were calculated using Judd-Ofelt theory. After that we calculated some predicted spectroscopic parameters, such as the spontaneous radiative transition rate, branching ratio and integrated emission cross section, which were then compared with the data of other common materials. It was found that there are many transitions with large oscillator strength and large integrated emission cross section, especially 2H11/2→4I15/2, 4S3/2→4I15/2, 4F9/2→4I15/2 and 4I13/2→4I15/2, which are useful in solid-state laser and communications fields. Finally, we discuss the splitting of the energy levels of Er3+ in the crystal GdVO4 through the group theory, and also analyze the intermix of Jz in Starks levels.

An interesting fluorescence intensity reverse photonic phenomenon between red and green fluorescence is investigated. The dynamic range Sigma of intensity reverse between red and green fluorescence of Er(0.5)Yb(3):FOV oxyfluoride nanophase vitroceramics, when excited by 378.5nm and 522.5nm light respectively, is about 4.32x10(2). It is calculated that the phonon-assistant energy transfer rate of the electric multi-dipole interaction of {(4)G(11/2)(Er(3+))?(4)F(9/2)(Er(3+)), (2)F(7/2)(Yb(3+))?(2)F(5/2)(Yb(3+))} energy transfer of Er(0.5)Yb(3):FOV is around 1.380x10(8)s(-1), which is much larger than the relative multiphonon nonradiative relaxation rates 3.20x10(5)s(-1). That energy transfer rate for general material with same rare earth ion's concentration is about 1.194x10(5)s(-1). These are the reason to emerge the unusual intensity reverse phenomenon in Er(0.5)Yb(3):FOV.

This paper reports the excited-state upconversion of Pr(0.5):ZBLAN glass under two-color excitation. It is found that the fluorescence of upconversion-emiss ion spectrum is the same as that of common-emission spectrum. It is found also that there are three obvious peaks on upconversionexcitation spectrum under twocolor excitation, which corresponds to the 788.5nm 1G4→3P2,850.5nm 1G4→1I6,and 805.0nm 3H6→1D2 excited state absorpt ion transitions res pectively. The large 850.5nm peak of upconversion-excitation spectrum results from the large 1G4(Pr3+ )→1I6(Pr3+) (Pr3+) oscil lator strength f=23.04×10-6. It illustrates the excited state absorp tion upconve rsion from 1G4 level, especially the 1G4(Pr3+)→1I6(Pr3+) upconversion process is large. It results in the upcon version luminescence of Pr(0.5):ZBLAN under two-color excitation.