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
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
A laser model which may operate in the absence of population inversion is proposed.It is found that the realization of lasing without inversion in this model is due to the change of noninversion condition along with t...A laser model which may operate in the absence of population inversion is proposed.It is found that the realization of lasing without inversion in this model is due to the change of noninversion condition along with the creation of atomic coherence,instead of a coherence-term-induced gain enhancement.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
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
对开放的V型三能级系统,通过微分方程的数值运算,分析了该系统的无粒子数反转激光(laser without inversion,LWI)产生的机制,讨论了探测场和驱动场的失谐、驱动场的Rabi频率、粒子初始状态对系统LWI时间演化的影响。结果显示:驱动场耦...对开放的V型三能级系统,通过微分方程的数值运算,分析了该系统的无粒子数反转激光(laser without inversion,LWI)产生的机制,讨论了探测场和驱动场的失谐、驱动场的Rabi频率、粒子初始状态对系统LWI时间演化的影响。结果显示:驱动场耦合的两个能级上的粒子数分布以相同的频率振荡,位相差π;在探测场和驱动场皆共振(△=△_0=0)时,原子对探测场色散的响应为零,双光子相干项ρ_(ca)是实量;驱动场的Rabi频率Ω增大时,增益、相干项和粒子数差的振荡周期减小;粒子数的初始状态主要影响增益、相干项和粒子数差的振荡幅度,并不影响最后的稳定状态。展开更多
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.
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A laser model which may operate in the absence of population inversion is proposed.It is found that the realization of lasing without inversion in this model is due to the change of noninversion condition along with the creation of atomic coherence,instead of a coherence-term-induced gain enhancement.
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,
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.
基金Supported by the Scientific Research sustentation fund for Young Teachers in the Higher Education Institutions of Anhui Province(Grant No.2005jq1133)
文摘对开放的V型三能级系统,通过微分方程的数值运算,分析了该系统的无粒子数反转激光(laser without inversion,LWI)产生的机制,讨论了探测场和驱动场的失谐、驱动场的Rabi频率、粒子初始状态对系统LWI时间演化的影响。结果显示:驱动场耦合的两个能级上的粒子数分布以相同的频率振荡,位相差π;在探测场和驱动场皆共振(△=△_0=0)时,原子对探测场色散的响应为零,双光子相干项ρ_(ca)是实量;驱动场的Rabi频率Ω增大时,增益、相干项和粒子数差的振荡周期减小;粒子数的初始状态主要影响增益、相干项和粒子数差的振荡幅度,并不影响最后的稳定状态。
