In this paper, spectral hole depth dependence on temperature below 10 K in Tm^3＋ ：YAG crystal is investigated in detail. A novel model is proposed to analyze the temperature dependence on the spectral hole. By using...In this paper, spectral hole depth dependence on temperature below 10 K in Tm^3＋ ：YAG crystal is investigated in detail. A novel model is proposed to analyze the temperature dependence on the spectral hole. By using the proposed model, we theoretically deduce the temperature dependence of spectral hole depth. The results are compared with experimental results and they are in good agreement. According to the theoretic results, the optimum temperature in experiment can be found.展开更多
By using an Ar+ ion laser, a tunable Rh 6G dye laser(Linewidth: 0.5 cm -1) and a Coherent 899-21 dye laser as light sources and using a monochromator and a phase-locking amplifier, the optical properties of Eu 3+∶Y_2...By using an Ar+ ion laser, a tunable Rh 6G dye laser(Linewidth: 0.5 cm -1) and a Coherent 899-21 dye laser as light sources and using a monochromator and a phase-locking amplifier, the optical properties of Eu 3+∶Y_2SiO_5 crystal were detected. Persistent spectral hole burning (PSHB) were also observed in 5D_0-7F_0 transition in the crystal at the temperature of 16 K. For 15 mW dye laser (Wavelength: 579.62 nm) burning the crystal for 0.1 s a spectral hole with about 80 MHz hole width were detected and the hole can been keep for longer than 10 h.展开更多
We demonstrate the possibility of creating a time gap in the slow light based on spectral hole burning in a fourlevel Doppler broadened sodium atomic system. A time gap is also observed between the slow and the fast l...We demonstrate the possibility of creating a time gap in the slow light based on spectral hole burning in a fourlevel Doppler broadened sodium atomic system. A time gap is also observed between the slow and the fast light in the hole burning region and near the burnt hole region, respectively. A cloaking time gap is attained in microseconds and no distortion is observed in the transmitted pulse. The width of the time gap is observed to vary with the inverse Doppler effect in this system. Our results may provide a way to create multiple time gaps for a temporal cloak.展开更多
By using an Ar^＋ ion laser, a tunable Rh6G dye laser（linewidth： 0.5 cm^-1） pumped by the second harmonic of a YAG：Nd laser and an 899-21 dye laser as light sources and using a monochromator, a phase-locking ampli...By using an Ar^＋ ion laser, a tunable Rh6G dye laser（linewidth： 0.5 cm^-1） pumped by the second harmonic of a YAG：Nd laser and an 899-21 dye laser as light sources and using a monochromator, a phase-locking amplifier and a computer as the data detecting system, the spectra and spectral hole burning of Eu^3＋：Y2SiO5 crystal were researched in this paper.Photoluminescence excitation spectrum and site selective fluorescence spectrum were detected at room temperature and 77 K. Hole burning experiments were reached at 16 K. A spectral hole with hole width of about 80 MHz were detected and it could be kept for 10 h.展开更多
Before and after X-irradiation, two photon spectral hole burning experiments in BaF (Cl,Br) : Sm2+ were performed by a 560 nm laser light at liquid nitrogen temperature. The results show that spectral hole burning of ...Before and after X-irradiation, two photon spectral hole burning experiments in BaF (Cl,Br) : Sm2+ were performed by a 560 nm laser light at liquid nitrogen temperature. The results show that spectral hole burning of Sm2+ doped fluoride halide mixed crystals are accompanied by photostimulated luminescence process. This process make hole burning efficiency decreased.展开更多
Spectral hole burning is investigated in an optical medium in the presence of Doppler broadening and Kerr nonlinearity. The Kerr nonlinearity generates coherent hole burning in the absorption spectrum. The higher orde...Spectral hole burning is investigated in an optical medium in the presence of Doppler broadening and Kerr nonlinearity. The Kerr nonlinearity generates coherent hole burning in the absorption spectrum. The higher order Kerr nonlinearity enhances the typical lamb dip of the hole. Normal dispersion in the hole burning region while Steep anomalous dispersion between the two hole burning regions also enhances with higher order Kerr effect. A large phase shift creates large delay or advancement in the pulse propagation while no distortion is observed in the pulse. These results provide significant steps to improve optical memory, telecom devices, preservation of information and image quality.展开更多
In this paper, the physical mechanism of the interaction between electromagnetic wave and spectral-hole burning crystal material is investigated in detail. In the small signal regime, a perturbation theory model is us...In this paper, the physical mechanism of the interaction between electromagnetic wave and spectral-hole burning crystal material is investigated in detail. In the small signal regime, a perturbation theory model is used to analyze the mechanism of spectral-hole burning. By solving the Liouville equation, three-order perturbation results are obtained. From the theoretic analysis, spectral-hole burning can be interpreted as a photon echo of the zero-order diffraction echo when the first optical pulse and the second optical pulse are overlapped in time. According to the model, the spectral-hole width is dependent on the chirp rate of the reading laser. When the chirp rate is slow with respect to the spectral features of interest, the spectral hole is closely mapped into time domain. For a fast chirp rate, distortions are observed. The results follow Maxwell-Bloch model and they are also in good agreement with the experimental results.展开更多
Dynamometer cards are commonly used to analyze down-hole working conditions of pumping systems in actual oil production. Nowadays, the traditional supervised learning methods heavily rely on the classification accurac...Dynamometer cards are commonly used to analyze down-hole working conditions of pumping systems in actual oil production. Nowadays, the traditional supervised learning methods heavily rely on the classification accuracy of the training samples. In order to reduce the errors of manual classification, an automatic clustering algorithm is proposed and applied to diagnose down-hole conditions of pumping systems. The spectral clustering （SC） is a new clustering algorithm, which is suitable for any data distribution. However, it is sensitive to initial cluster centers and scale parameters, and needs to predefine the cluster number. In order to overcome these shortcom- ings, we propose an automatic clustering algorithm, fast black hole-spectral clustering （FBH-SC）. The FBH algo- rithm is used to replace the K-mean method in SC, and a CritC index function is used as the target function to automatically choose the best scale parameter and clus- tering number in the clustering process. Different simulation experiments were designed to define the relationship among scale parameter, clustering number, CritC index value, and clustering accuracy. Finally, an example is given to validate the effectiveness of the proposed algorithm.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 11004152)the Science Fund of Tianjin Education Commission (Grant Nos. 20090715 and 20110704)
文摘In this paper, spectral hole depth dependence on temperature below 10 K in Tm^3＋ ：YAG crystal is investigated in detail. A novel model is proposed to analyze the temperature dependence on the spectral hole. By using the proposed model, we theoretically deduce the temperature dependence of spectral hole depth. The results are compared with experimental results and they are in good agreement. According to the theoretic results, the optimum temperature in experiment can be found.
文摘By using an Ar+ ion laser, a tunable Rh 6G dye laser(Linewidth: 0.5 cm -1) and a Coherent 899-21 dye laser as light sources and using a monochromator and a phase-locking amplifier, the optical properties of Eu 3+∶Y_2SiO_5 crystal were detected. Persistent spectral hole burning (PSHB) were also observed in 5D_0-7F_0 transition in the crystal at the temperature of 16 K. For 15 mW dye laser (Wavelength: 579.62 nm) burning the crystal for 0.1 s a spectral hole with about 80 MHz hole width were detected and the hole can been keep for longer than 10 h.
基金supported by the Higher Education Commission(HEC)of Pakistan
文摘We demonstrate the possibility of creating a time gap in the slow light based on spectral hole burning in a fourlevel Doppler broadened sodium atomic system. A time gap is also observed between the slow and the fast light in the hole burning region and near the burnt hole region, respectively. A cloaking time gap is attained in microseconds and no distortion is observed in the transmitted pulse. The width of the time gap is observed to vary with the inverse Doppler effect in this system. Our results may provide a way to create multiple time gaps for a temporal cloak.
文摘By using an Ar^＋ ion laser, a tunable Rh6G dye laser（linewidth： 0.5 cm^-1） pumped by the second harmonic of a YAG：Nd laser and an 899-21 dye laser as light sources and using a monochromator, a phase-locking amplifier and a computer as the data detecting system, the spectra and spectral hole burning of Eu^3＋：Y2SiO5 crystal were researched in this paper.Photoluminescence excitation spectrum and site selective fluorescence spectrum were detected at room temperature and 77 K. Hole burning experiments were reached at 16 K. A spectral hole with hole width of about 80 MHz were detected and it could be kept for 10 h.
文摘Before and after X-irradiation, two photon spectral hole burning experiments in BaF (Cl,Br) : Sm2+ were performed by a 560 nm laser light at liquid nitrogen temperature. The results show that spectral hole burning of Sm2+ doped fluoride halide mixed crystals are accompanied by photostimulated luminescence process. This process make hole burning efficiency decreased.
基金Supported by Higher Education Commission(HEC)of Pakistan
文摘Spectral hole burning is investigated in an optical medium in the presence of Doppler broadening and Kerr nonlinearity. The Kerr nonlinearity generates coherent hole burning in the absorption spectrum. The higher order Kerr nonlinearity enhances the typical lamb dip of the hole. Normal dispersion in the hole burning region while Steep anomalous dispersion between the two hole burning regions also enhances with higher order Kerr effect. A large phase shift creates large delay or advancement in the pulse propagation while no distortion is observed in the pulse. These results provide significant steps to improve optical memory, telecom devices, preservation of information and image quality.
基金supported by the Special Funds for Scientific and Technological Innovation Projects,Tianjin,China(Grant No.10FDZDGX00400)
文摘In this paper, the physical mechanism of the interaction between electromagnetic wave and spectral-hole burning crystal material is investigated in detail. In the small signal regime, a perturbation theory model is used to analyze the mechanism of spectral-hole burning. By solving the Liouville equation, three-order perturbation results are obtained. From the theoretic analysis, spectral-hole burning can be interpreted as a photon echo of the zero-order diffraction echo when the first optical pulse and the second optical pulse are overlapped in time. According to the model, the spectral-hole width is dependent on the chirp rate of the reading laser. When the chirp rate is slow with respect to the spectral features of interest, the spectral hole is closely mapped into time domain. For a fast chirp rate, distortions are observed. The results follow Maxwell-Bloch model and they are also in good agreement with the experimental results.
基金the National Natural Science Foundation of China (Grant No. 61403040)
文摘Dynamometer cards are commonly used to analyze down-hole working conditions of pumping systems in actual oil production. Nowadays, the traditional supervised learning methods heavily rely on the classification accuracy of the training samples. In order to reduce the errors of manual classification, an automatic clustering algorithm is proposed and applied to diagnose down-hole conditions of pumping systems. The spectral clustering （SC） is a new clustering algorithm, which is suitable for any data distribution. However, it is sensitive to initial cluster centers and scale parameters, and needs to predefine the cluster number. In order to overcome these shortcom- ings, we propose an automatic clustering algorithm, fast black hole-spectral clustering （FBH-SC）. The FBH algo- rithm is used to replace the K-mean method in SC, and a CritC index function is used as the target function to automatically choose the best scale parameter and clus- tering number in the clustering process. Different simulation experiments were designed to define the relationship among scale parameter, clustering number, CritC index value, and clustering accuracy. Finally, an example is given to validate the effectiveness of the proposed algorithm.
