A faster numerical method based on FDTD for the four energy level atomic system is present here. The initial conditions for the electrons of each level are achieving while the fields are in steady state. Polarization ...A faster numerical method based on FDTD for the four energy level atomic system is present here. The initial conditions for the electrons of each level are achieving while the fields are in steady state. Polarization equation, rate equations of electronic population and Maxwell’s equations were used to describe the coupling between the atoms and electromagnetic wave. Numerical simulations, based on a finite-difference time-domain (FDTD) method, were utilized to obtain the population inversion and lasing threshold. The validity of the model and its theory is confirmed. The time, which we can observe the lasing phenomenon, is much shorter in our new model. Our model can be put into using in large scale simulations in mutiphysics to reduce the total simulated time.展开更多
We have studied the effect of the spontaneously generated coherence （SGC） on gain of lasing without inversion （LWI） in a closed three-level A-type atomic system with Doppler broadening. It is shown that, regardles...We have studied the effect of the spontaneously generated coherence （SGC） on gain of lasing without inversion （LWI） in a closed three-level A-type atomic system with Doppler broadening. It is shown that, regardless of the driving and probe fields being co- or counter-propagating, at a suitable value of the Doppler width, we can obtain a much larger LWI gain with SGC than that without SGC; and the region of the LWI gain spectrum with SGC is obviously larger than that without SGC. When the Doppler width takes a constant value, the gain does not monotonically decrease or increase with increasing strength of SGC, the largest LWI gain can be obtained by adjusting strength of SGC. Generally speaking, the co-propagating probe and driving fields is favourable to obtain a larger LWI gain.展开更多
Recently more attention has been paid to the study of lasing without population inver-sion. It has been found that many schemes, with the help of optical coherence or quantuminterference effect, may establish such opt...Recently more attention has been paid to the study of lasing without population inver-sion. It has been found that many schemes, with the help of optical coherence or quantuminterference effect, may establish such optical phenomenon as that in refs. [1-7]. In thoselaser models, in order to have the optical gain on the corresponding transition a coherentpump is required to drive the systems, and additional pumps, coherent or incoherent,展开更多
文摘A faster numerical method based on FDTD for the four energy level atomic system is present here. The initial conditions for the electrons of each level are achieving while the fields are in steady state. Polarization equation, rate equations of electronic population and Maxwell’s equations were used to describe the coupling between the atoms and electromagnetic wave. Numerical simulations, based on a finite-difference time-domain (FDTD) method, were utilized to obtain the population inversion and lasing threshold. The validity of the model and its theory is confirmed. The time, which we can observe the lasing phenomenon, is much shorter in our new model. Our model can be put into using in large scale simulations in mutiphysics to reduce the total simulated time.
基金This project was financially supported by the National Natural Science Foundation of China (Grant 10564005)the Project of Science and Technology of Yunnan University (Grant 2004Z008C)
基金Project supported by the National Natural Science Foundation of China （Grant No 10675076）, the Natural Science Foundation of Shandong Province, China （Grant No Y2006A21） and the State Key Laboratory of High Field Laser Physics, Shanghai Institute of 0ptics and Fine Mechanics, Chinese Academy of Sciences.
文摘We have studied the effect of the spontaneously generated coherence （SGC） on gain of lasing without inversion （LWI） in a closed three-level A-type atomic system with Doppler broadening. It is shown that, regardless of the driving and probe fields being co- or counter-propagating, at a suitable value of the Doppler width, we can obtain a much larger LWI gain with SGC than that without SGC; and the region of the LWI gain spectrum with SGC is obviously larger than that without SGC. When the Doppler width takes a constant value, the gain does not monotonically decrease or increase with increasing strength of SGC, the largest LWI gain can be obtained by adjusting strength of SGC. Generally speaking, the co-propagating probe and driving fields is favourable to obtain a larger LWI gain.
文摘Recently more attention has been paid to the study of lasing without population inver-sion. It has been found that many schemes, with the help of optical coherence or quantuminterference effect, may establish such optical phenomenon as that in refs. [1-7]. In thoselaser models, in order to have the optical gain on the corresponding transition a coherentpump is required to drive the systems, and additional pumps, coherent or incoherent,
