We study the double barrier tunneling properties of Dirac particles in spin-orbit coupled Bose–Einstein Condensates.The analytic expression of the transmission coefficient of Dirac particles penetrating into a double...We study the double barrier tunneling properties of Dirac particles in spin-orbit coupled Bose–Einstein Condensates.The analytic expression of the transmission coefficient of Dirac particles penetrating into a double barrier is obtained.An interesting resonance tunneling phenomenon is discovered in the Klein block region which has been ignored before.展开更多
The strong effective magnetic fields with flux to the order of one flux quantum per plaquette has been realized for ultracold atoms,and the quantum cyclotron orbit of a single atom in a single plaquette exposed to the...The strong effective magnetic fields with flux to the order of one flux quantum per plaquette has been realized for ultracold atoms,and the quantum cyclotron orbit of a single atom in a single plaquette exposed to the magnetic field was directly revealed recently [Phys.Rev.Lett.107 (2011) 255301].We study the quantum cyclotron orbits of a bosonic atom in a triple well with a synthetic gauge field,and find that the dynamics of the atom in real space is similar to a classical dynamic billiard.It is interesting that the billiard-like motion is a signature of the quantum evolution of the three-level system,and its behaviors are determined by the ratio of the two energy gaps of the three energy levels.展开更多
A compact single-mode distributed Bragg reflector (DBR) fiber laser with narrow spectral linewidth is investigated. Firstly, based on our theoretical analysis the single longitudinal mode operation domain is obtained....A compact single-mode distributed Bragg reflector (DBR) fiber laser with narrow spectral linewidth is investigated. Firstly, based on our theoretical analysis the single longitudinal mode operation domain is obtained. Then, a single-mode DBR fiber laser of 7.9cm long with master oscillator power amplifier (MOPA) configuration is designed and constructed to operate in the single-mode domain. The fiber laser is pumped by a semiconductor laser at 975.5nm. The master oscillator operates at 1556.91 nm with a cw output power of 1.43mW for a pump power of 55.35 mW. Its slope efficiency is 2.7% and the spectral linewidth is less than 1.2MHz (instrument resolution limited). With the MOPA configuration the laser output power and slope efficiency are increased to 7.8mW and 16.9%, respectively.展开更多
We describe a new method for applying a strain gradient with different profiles to convert uniform fiber Bragg gratings into linear or non-linear chirped ones. The chirping profile and the chirp rate of the fiber grat...We describe a new method for applying a strain gradient with different profiles to convert uniform fiber Bragg gratings into linear or non-linear chirped ones. The chirping profile and the chirp rate of the fiber gratings can be controlled by simply varying the tension applied. Both the theory and experimental results are presented.展开更多
An electrically tunable optical fibre Macli-Zehnder interferometer is reported,based on the magnetostrictive effect.The period and peak wavelength of the interference spectrum can be electrically tuned to match the In...An electrically tunable optical fibre Macli-Zehnder interferometer is reported,based on the magnetostrictive effect.The period and peak wavelength of the interference spectrum can be electrically tuned to match the International Telecommunication Union standard wavelength grid and so it is promising to be used in dense wavelength division multiplexing technology.展开更多
Hydrogen loading provides highly enhanced photosensitivity in Ge-doped fiber. But the Bragg wavelength of UV-written fiber grating will shift from its initial value as the remaining hydrogen diffuses out of such fiber...Hydrogen loading provides highly enhanced photosensitivity in Ge-doped fiber. But the Bragg wavelength of UV-written fiber grating will shift from its initial value as the remaining hydrogen diffuses out of such fiber. A simple model to calculate the index change of hydrogenated fibers is presented. The theoretical model is in good agreement with experimental results and it can well predict the final wavelength position of UV-written weak fiber grating.展开更多
Optical loss spectra and refractive index changes have been measured in the hydrogenated standard telecommu-nication fiber and photosensitive fiber.The index changes due to ultraviolet exposure were found to be closel...Optical loss spectra and refractive index changes have been measured in the hydrogenated standard telecommu-nication fiber and photosensitive fiber.The index changes due to ultraviolet exposure were found to be closely related with the OH formation in both types of fibers.A direct photolyticd model is proposed to explain the effect of hydrogen loading on the enhancement of the photosensitivity in silica fibers.展开更多
基金Supported by the National Basic Research Program of China under Grant No 2011CB921503the National Natural Science Foundation of China under Grant Nos 11075020 and 91021021.
文摘We study the double barrier tunneling properties of Dirac particles in spin-orbit coupled Bose–Einstein Condensates.The analytic expression of the transmission coefficient of Dirac particles penetrating into a double barrier is obtained.An interesting resonance tunneling phenomenon is discovered in the Klein block region which has been ignored before.
基金Supported by the National Basic Research Program of China under Grant No 2011CB921500the National Natural Science Foundation of China under Grant Nos 10725521,11075020 and 11078001.
文摘The strong effective magnetic fields with flux to the order of one flux quantum per plaquette has been realized for ultracold atoms,and the quantum cyclotron orbit of a single atom in a single plaquette exposed to the magnetic field was directly revealed recently [Phys.Rev.Lett.107 (2011) 255301].We study the quantum cyclotron orbits of a bosonic atom in a triple well with a synthetic gauge field,and find that the dynamics of the atom in real space is similar to a classical dynamic billiard.It is interesting that the billiard-like motion is a signature of the quantum evolution of the three-level system,and its behaviors are determined by the ratio of the two energy gaps of the three energy levels.
基金Supported by Doctoral Program Foundation of Institution of Higher Education under Grant No.9600106the NationalNatural Science Foundation of China under Grant No.69637050.
文摘A compact single-mode distributed Bragg reflector (DBR) fiber laser with narrow spectral linewidth is investigated. Firstly, based on our theoretical analysis the single longitudinal mode operation domain is obtained. Then, a single-mode DBR fiber laser of 7.9cm long with master oscillator power amplifier (MOPA) configuration is designed and constructed to operate in the single-mode domain. The fiber laser is pumped by a semiconductor laser at 975.5nm. The master oscillator operates at 1556.91 nm with a cw output power of 1.43mW for a pump power of 55.35 mW. Its slope efficiency is 2.7% and the spectral linewidth is less than 1.2MHz (instrument resolution limited). With the MOPA configuration the laser output power and slope efficiency are increased to 7.8mW and 16.9%, respectively.
基金the National Natural Science Foundation of China under Grant Nos.69777008 and 69637050.
文摘We describe a new method for applying a strain gradient with different profiles to convert uniform fiber Bragg gratings into linear or non-linear chirped ones. The chirping profile and the chirp rate of the fiber gratings can be controlled by simply varying the tension applied. Both the theory and experimental results are presented.
基金Supported by the National Natural Science Foundation of China under Grant Nos.69777008 and 69637050.
文摘An electrically tunable optical fibre Macli-Zehnder interferometer is reported,based on the magnetostrictive effect.The period and peak wavelength of the interference spectrum can be electrically tuned to match the International Telecommunication Union standard wavelength grid and so it is promising to be used in dense wavelength division multiplexing technology.
基金Supported by the National Natural Science Foundation of China under Grant Nos.69777008 and 69637050.
文摘Hydrogen loading provides highly enhanced photosensitivity in Ge-doped fiber. But the Bragg wavelength of UV-written fiber grating will shift from its initial value as the remaining hydrogen diffuses out of such fiber. A simple model to calculate the index change of hydrogenated fibers is presented. The theoretical model is in good agreement with experimental results and it can well predict the final wavelength position of UV-written weak fiber grating.
基金Supported by the National Natural Science Foundation of China under Grant No.69637050。
文摘Optical loss spectra and refractive index changes have been measured in the hydrogenated standard telecommu-nication fiber and photosensitive fiber.The index changes due to ultraviolet exposure were found to be closely related with the OH formation in both types of fibers.A direct photolyticd model is proposed to explain the effect of hydrogen loading on the enhancement of the photosensitivity in silica fibers.
