Yao Li
East China Normal University
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Featured researches published by Yao Li.
Applied Physics Letters | 2008
Huafang Dong; Haifeng Pan; Yao Li; E Wu; Heping Zeng
We demonstrated an efficient single-photon frequency upconversion system for the infrared photons at 1.06u2009μm with ultralow background counts. By pumping the system at a longer wavelength than that of the single-photon signal, the background counts caused by the pump-induced parametric fluorescence in the nonlinear crystal were reduced markedly. We achieved so far the lowest noise of ∼150/s for a near unity conversion efficiency.We demonstrated an efficient single-photon frequency upconversion system for the infrared photons at 1.06u2009μm with ultralow background counts. By pumping the system at a longer wavelength than that of the single-photon signal, the background counts caused by the pump-induced parametric fluorescence in the nonlinear crystal were reduced markedly. We achieved so far the lowest noise of ∼150/s for a near unity conversion efficiency.
Applied Physics Letters | 2010
Xiaorong Gu; Kun Huang; Yao Li; Haifeng Pan; E Wu; Heping Zeng
We demonstrate efficient single-photon detection at 1.04u2002μm with quite low background counts by using the frequency upconversion detection technique with pulsed single-photon source and strong pump field prepared from two synchronized fiber lasers. Temporal and spectral control of the pump and signal lasers enabled an upconversion efficiency of 81.1%. As the system was pumped at a wavelength longer than that of the signal, the corresponding background counts were reduced down to 1.5×103u2002s−1 due to efficient suppression of parametric fluorescence in the periodic poled lithium niobate crystal.
Applied Physics Letters | 2007
Zhigao Hu; Yao Li; Fangyu Yue; Ziqiang Zhu; Junhao Chu
Optical properties of ferroelectric Bi3.25La0.75Ti3O12 (BLT) films on quartz have been investigated using ultraviolet-infrared transmittance spectra in the temperature range of 77–500K. The spectra can be divided into three distinctive photon regions between 1.1 and 6.5eV. It is found that the band gap Eg decreases from 3.88to3.77eV with the temperature. The parameters aB and ΘB of the Bose-Einstein model are 30.3meV and 218.7K, respectively. The band narrowing coefficient dEg∕dT is −2.65×10−4eV∕K at room temperature. The present results can be crucial for future application of ferroelectric BLT-based electro-optic and high temperature optoelectronic devices.
Applied Physics Letters | 2007
Yao Li; Zhigao Hu; Fangyu Yue; G. Y. Yang; Wangzhou Shi; X. J. Meng; J. L. Sun; Junhao Chu
The 70%Pb(Mg1∕3,Nb2∕3)O3–30%PbTiO3 (PMNT) films have been fabricated on LaNiO3 (LNO) coated silicon substrate. The conductive LNO films act as a seed layer for the growth of PMNT films, which depresses the formation of pyrochlore phase and induces the high (100) preferred orientation of perovskite PMNT films. Compared with the PMNT films grown on platinum bottom electrode, the ferroelectric properties of PMNT films grown on LNO are enhanced. The frequency dependence of complex permittivity from PMNT films on LNO is the conjunct result of polarization relaxation and movement of oxygen vacancy, which can be fitted by the function containing Debye and universal dielectric response models, respectively.
Applied Physics Letters | 2008
Yao Li; Zhigao Hu; J. L. Sun; X. J. Meng; J. H. Chu
CaCu3Ti4O12 (CCTO) thin films are prepared by a sol-gel method on LaNiO3-coated silicon and Pt∕TiO2∕SiO2∕Si substrate. Compared with the films on Pt, the CCTO on LaNiO3 exhibits a (400) orientation. Dielectric loss of CCTO on LaNiO3 is lower than 0.25 within 100Hz–10kHz, lower than the reported value of CCTO grown on Pt∕TiO2∕SiO2∕Si by pulse laser deposition. Possible reason is that LaNiO3 acts as seed layer for the growth of CCTO. The crystallinity of CCTO is improved and the dielectric properties are enhanced. Complex impedance spectrum of CCTO on LaNiO3 is discussed according to grain boundary barrier layer capacitance model.
IEEE Journal of Selected Topics in Quantum Electronics | 2009
Xiaorong Gu; Yao Li; Haifeng Pan; E Wu; Heping Zeng
Single-photon signals at 1.56 ¿m were converted into the visible region by sum-frequency generation, with synchronous pump pulses at 1.03 ¿m in a periodically poled lithium niobate crystal. The signal and pump sources were provided by two synchronized mode-locked fiber lasers at the operation rate of 7.88 MHz. Such a high-speed single-photon upconversion system has shown an overall detection efficiency of 10.4%. The corresponding background noise was measured to be 3.3 × 103 s-1. The noise-equivalent power in this scheme was 9.93 × 10-17 W/Hz1/2, which was the lowest compared to the other upconversion systems with similar pump and signal wavelengths.
Physical Review A | 2006
Guang Wu; Jie Chen; Yao Li; Lilin Xu; Heping Zeng
We analyze application of bright reference pulses to prevent the photon-number-splitting attack in weak-pulse quantum key distribution. Under the analyzed eavesdropping strategy, the optimal parameters of bright reference and signal pulses can ensure a secure transmission distance up to 146 km. To realize the quantum key distribution scenario with up-present techniques, we present an experimentally feasible scheme to create a large splitting ratio between bright reference and signal pulses, and to switch the bright reference pulses away from signal pulses to avoid the after-pulse disturbance.
Journal of Modern Optics | 2009
Guang Wu; Lilin Xu; Jie Chen; Yao Li; Xiaorong Gu; E Wu; Heping Zeng
A highly sensitive fiber-coupled single-photon spectrum analyzer is built based on a InGaAs/InP avalanche photodiode single-photon detector operated in Geiger mode. This device is capable of analyzing weak light signals with less than 3.6 × 10−4 photon pulse−1 in the spectral range from 1390 to 1600 nm. We have used it to measure the spectrum of the weak nonlinear signal of the fiber caused by the clock pulse in the quantum key distribution experiment. The spectral information will help to eliminate the nonlinear background in the fiber and improve the performance of the system.
Archive | 2009
Jie Chen; Lilin Xu; Yao Li; Xiaorong Gu; Heping Zeng
Archive | 2008
Haifeng Pan; Huafang Dong; Yao Li; Heping Zeng