This paper investigates the control role of the relative phase between the probe and driving fields on the gain, dispersion and populations in an open A system with spontaneously generated coherence （SGC）. It shows ...This paper investigates the control role of the relative phase between the probe and driving fields on the gain, dispersion and populations in an open A system with spontaneously generated coherence （SGC）. It shows that by adjusting the value of the relative phase, a change from lasing with inversion to lasing without inversion can be realized; the values and frequency spectrum regions of the inversionless gain and dispersion can be obviously varied; high refractive index with zero absorption and electromagnetically induced transparency can be achieved. It is also found that when the driving field is resonant, the shapes of the dispersion and the gain curves versus the probe detuning are very similar if the relative phase of the dispersion lags π/2 than that of the gain, however for the off-resonant driving field the similarity will disappear; the gain, dispersion and populations are periodical functions of the relative phase, the modulation period is always 2π; the contribution of SGC to the inversionless gain and dispersion is much larger than that of the dynamically induced coherence.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
This paper studies the propagation effect in a closed lambda-type three-level atomic system with Doppler broadening. It is shown that, Doppler broadening due to atomic motion and propagation effect associated with dri...This paper studies the propagation effect in a closed lambda-type three-level atomic system with Doppler broadening. It is shown that, Doppler broadening due to atomic motion and propagation effect associated with driving field depletion along the active medium decreases obviously the gain and output of the lasing without inversion （LWI）; the relative phase between the probe and driving fields has a remarkable modulation role to the propagation effect on LWI when Doppler broadening presents; by choosing suitable value of the relative phase, we can get the largest gain and output of LWI.展开更多
In this paper we study influences of Doppler broadening, spontaneously generated coherence, and other system parameters on propagation effect in a quasi lambda-type four-level atomic system. It is shown that when the ...In this paper we study influences of Doppler broadening, spontaneously generated coherence, and other system parameters on propagation effect in a quasi lambda-type four-level atomic system. It is shown that when the Doppler broadening is present, generally speaking, the values of gain and intensity of lasing without inversion （i.e. the probe field） in the co-propagating probe and driving fields case are much larger than those in the counter-propagating case; considerably larger gain and intensity of lasing without inversion than those without the Doppler broadening can be obtained by choosing appropriate values of the Doppler broadening width and spontaneously generated coherence strength. The gain and intensity of lasing without inversion increase with the increase of spontaneously generated coherence strength; when spontaneously generated coherence is present, much larger gain and intensity of lasing without inversion than those in the case without spontaneously generated coherence can be obtained. Choosing suitable values of the probe detuning, Rabi frequencies of the driving and pump fields at the entrance of the medium also can remarkably enhance the gain and intensity of lasing without inversion.展开更多
We study the lasing without inversion in a four-level diamond configuration in the case of incoherent pumping field within the framework of the bare-state basis. With the strong fields limit, we obtain the approximate...We study the lasing without inversion in a four-level diamond configuration in the case of incoherent pumping field within the framework of the bare-state basis. With the strong fields limit, we obtain the approximate steady-state solution, and discuss the dependence of population distribution and system gain on probe detuning and auxiliary field Rabi frequency.展开更多
Lasing without inversion can be obtained in the medium consisting of atoms of three-level cascade decay system by choosing the incoherently pumping rates if atomic coherence is produced by an external electromagnetic ...Lasing without inversion can be obtained in the medium consisting of atoms of three-level cascade decay system by choosing the incoherently pumping rates if atomic coherence is produced by an external electromagnetic field at two lower levels.Discussions are made on strong external field and resonance cases,respectively.Meanwhile,based on numerical calculations,it is found that a large index of refraction with vanishing absorption and dispersion can be achieved for the probe light of a certain frequency in this medium.展开更多
文摘This paper investigates the control role of the relative phase between the probe and driving fields on the gain, dispersion and populations in an open A system with spontaneously generated coherence （SGC）. It shows that by adjusting the value of the relative phase, a change from lasing with inversion to lasing without inversion can be realized; the values and frequency spectrum regions of the inversionless gain and dispersion can be obviously varied; high refractive index with zero absorption and electromagnetically induced transparency can be achieved. It is also found that when the driving field is resonant, the shapes of the dispersion and the gain curves versus the probe detuning are very similar if the relative phase of the dispersion lags π/2 than that of the gain, however for the off-resonant driving field the similarity will disappear; the gain, dispersion and populations are periodical functions of the relative phase, the modulation period is always 2π; the contribution of SGC to the inversionless gain and dispersion is much larger than that of the dynamically induced coherence.
基金Supported by the Scientific Research sustentation fund for Young Teachers in the Higher Education Institutions of Anhui Province(Grant No.2005jq1133)
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,
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)
文摘This paper studies the propagation effect in a closed lambda-type three-level atomic system with Doppler broadening. It is shown that, Doppler broadening due to atomic motion and propagation effect associated with driving field depletion along the active medium decreases obviously the gain and output of the lasing without inversion （LWI）; the relative phase between the probe and driving fields has a remarkable modulation role to the propagation effect on LWI when Doppler broadening presents; by choosing suitable value of the relative phase, we can get the largest gain and output of LWI.
基金supported by the National Natural Science Foundation of China (Grant No.10875072)
文摘In this paper we study influences of Doppler broadening, spontaneously generated coherence, and other system parameters on propagation effect in a quasi lambda-type four-level atomic system. It is shown that when the Doppler broadening is present, generally speaking, the values of gain and intensity of lasing without inversion （i.e. the probe field） in the co-propagating probe and driving fields case are much larger than those in the counter-propagating case; considerably larger gain and intensity of lasing without inversion than those without the Doppler broadening can be obtained by choosing appropriate values of the Doppler broadening width and spontaneously generated coherence strength. The gain and intensity of lasing without inversion increase with the increase of spontaneously generated coherence strength; when spontaneously generated coherence is present, much larger gain and intensity of lasing without inversion than those in the case without spontaneously generated coherence can be obtained. Choosing suitable values of the probe detuning, Rabi frequencies of the driving and pump fields at the entrance of the medium also can remarkably enhance the gain and intensity of lasing without inversion.
基金Project supported by the K.C.Wong Magna Foundation of Ningbo University,China
文摘We study the lasing without inversion in a four-level diamond configuration in the case of incoherent pumping field within the framework of the bare-state basis. With the strong fields limit, we obtain the approximate steady-state solution, and discuss the dependence of population distribution and system gain on probe detuning and auxiliary field Rabi frequency.
文摘Lasing without inversion can be obtained in the medium consisting of atoms of three-level cascade decay system by choosing the incoherently pumping rates if atomic coherence is produced by an external electromagnetic field at two lower levels.Discussions are made on strong external field and resonance cases,respectively.Meanwhile,based on numerical calculations,it is found that a large index of refraction with vanishing absorption and dispersion can be achieved for the probe light of a certain frequency in this medium.
