Yaxun Zhou

State-selective energy transfer from Er3+ to Eu3+ in Bi2O3-GeO2-Ga2O3-Na2O glasses.

The Eu(3+) ion was introduced into Er(3+) doped Bi(2)O(3)-GeO(2)-Ga(2)O(3)-Na(2)O (BGGN) glasses to improve the 1.5 microm band emission. As a function of Eu(2)O(3) doped content, we observed the increase in non-radiative decay rate of Er(3+) not only (4)I(11/2) energy level but also (4)I(13/2) energy level, while the lifetime of Er(3+):(4)I(11/2) and (4)I(13/2) levels were shortened from 607 to 241 micros and from 3.37 to 1.88 ms, respectively. Accordingly, the upconversion fluorescence (green and red) was quenched. The total quantum efficiency of the Er(3+):(4)I(13/2) increased with the Eu(2)O(3) content increasing up to 0.2 mol% due to the state-selective energy transfer from Er(3+) to Eu(3+).

Entanglement of one-dimensional spin chains

Entanglement in one-dimensional Heisenberg model is investigated by Bethe ansatz method. By this approach, the reduced density matrix between any pair of spins in the chain can be obtained for ground state, and excited states as well. Especially, the reduced density matrix for nearest-neighbor spins has the block-diagonal form. Therefore, we can compute the concurrence of spin pairs in the chain steadily.

Structure and spectroscopic properties of Er3+/Ce3+ co-doped TeO2-Bi2O3-TiO2 glasses modified with various WO3 contents for 1.53 μm emission

The Er3+/Ce3+co-doped tellurite-based glasses(TeO2-Bi2O3-TiO2)modified with various WO3contents are prepared using conventional melt-quenching technique.The X-ray diffraction(XRD)patterns and Raman spectra of glass samples are measured to investigate the structures.The absorption spectra,the up-conversion emission spectra,the 1.53μm band fluorescence spectra and the lifetime of Er3+:4I13/2level are measured,and the amplification quality factors of Er3+are calculated to evaluate the effect of WO3contents on the 1.53μm band spectroscopic properties.With the introduction of WO3,it is found that the prepared tellurite-based glasses maintain the amorphous structure,while the1.53μm band fluorescence intensity of Er3+is improved evidently,and the fluorescence full width at half maximum(FWHM)is broadened accordingly.In addition,the prepared tellurite-based glass samples have larger bandwidth quality factor than silicate and germanate glasses.The results indicate that the prepared Er3+/Ce3+co-doped tellurite-based glass with a certain amount of WO3is an excellent gain medium applied for the 1.53μm band Er3+-doped fiber amplifier(EDFA).

Structure and spectroscopic properties of Er 3+ /Ce 3+ co-doped TeO 2 -Bi 2 O 3 -TiO 2 glasses modified with various WO 3 contents for 1.53 μm emission

The Er3+/Ce3+co-doped tellurite-based glasses(TeO2-Bi2O3-TiO2)modified with various WO3contents are prepared using conventional melt-quenching technique.The X-ray diffraction(XRD)patterns and Raman spectra of glass samples are measured to investigate the structures.The absorption spectra,the up-conversion emission spectra,the 1.53μm band fluorescence spectra and the lifetime of Er3+:4I13/2level are measured,and the amplification quality factors of Er3+are calculated to evaluate the effect of WO3contents on the 1.53μm band spectroscopic properties.With the introduction of WO3,it is found that the prepared tellurite-based glasses maintain the amorphous structure,while the1.53μm band fluorescence intensity of Er3+is improved evidently,and the fluorescence full width at half maximum(FWHM)is broadened accordingly.In addition,the prepared tellurite-based glass samples have larger bandwidth quality factor than silicate and germanate glasses.The results indicate that the prepared Er3+/Ce3+co-doped tellurite-based glass with a certain amount of WO3is an excellent gain medium applied for the 1.53μm band Er3+-doped fiber amplifier(EDFA).

Amplifying Performance of Er3+-doped Chalcogenide Microstructured Optical Fiber Amplifier

An amplifying model of Er3+-doped chalcogenide glass (Ga5Ge20Sb10S65) microstructured optical fiber (MOF) amplifier under the excitation of 980nm is presented to demonstrate the feasibility of Er3+-doped chalcogenide glass MOF applied for 1.53µm-band optical communication. By the numerical solving of the Er3+-ion population rate equations and light power propagation equations, the amplifying performances of 1.53µm-band signals for Er3+-doped chalcogenide glass MOF amplifier are investigated theoretically. The results show that the Er3+-doped chalcogenide glass MOF exhibits a higher signal gain and very broad gain spectrum, its maximum gain for small-signal input (-40dBm) exceeds 22dB on the 300cm MOF length under the excitation of 200mW pump power. Moreover, the relations of 1.53µm signal gain with fiber length and pump power are studied and analyzed. The theoretical studies indicate that the Er3+-doped Ga5Ge20Sb10S65 chalcogenide glass MOF is an excellent gain media which can be applied to broadband amplifiers operating in the third communication window.