Effect of exit and injection rates on phase-dependent transient evolution of gain without inversion

Abstract

It is shown that in an open -type system with spontaneously generated coherence, the transient evolution rule of the gain of lasing without inversion (LWI ) is very sensitive to variation of the relative phase between the probe and driving fields; the variety of the atomic exit rate 0 and the ratio C of the atomic injection rates also have a considerable effect on the phase-dependent transient evolution rule of LWI gain. We find that when =0, the transient and stationary LWI gain increases with C increasing but decreases with 0 increasing; when 0 , the effect of C and 0 on LWI gain is just opposite to that when =0 ; in order to get the largest transient and stationary LWI gain, we need selecting suitable values of , 0 and C. CLC numbers: TN241 Document code: A Article ID:Quantum coherence and interference in atomic systems can lead to many interesting phenomena such as lasing without inversion (LWI), electromagnetically induced transparency (EIT), coherent population trapping (CPT) and so on, in which LWI gets special attention due to its important application value [1] . There are many methods to produce conherence. A kind of coherence can be created by interference of spontaneous emission between different channels, which is usually called as spontaneously generated coherence (SGC), and it depends on the nonorthogonality of dipole moments. Recently, the effects of SGC on gain (absorption), dispersion, population and spontaneous emission spectrum etc. have widely been studied. In addition, the investigations have shown that the properties of the system with SGC relate closely to the relative phase between the applied fields [2][3][4][5][6][7][8][9][10] . However, these studies are usually made for the closed atomic systems. We have studied the effects of the relative phase on LWI gain (absorption) and dispersion of the steady state [11] , propagation of a light pulse [12,13] in an open -type threelevel atomic system with SGC. In this paper, we will investigate the effect of the relative phase on the transient evolution rule of the LWI gain in the open system, and analyze the manipulation role of the atomic exit rate and ratio of the atomic injection rates on the phase-dependent transient evolution of LWI gain. In our best knowledge this is also the first time to study the phase-dependent transient evolution of atomic response in an open atomic system.An open -type three-level atomic system is considered with an upper state |1> and two lower close-lying states |2> and |3>, as illustrated in Fig.1.Transition between |1> and |2> is driven by a strong coherent driving field with the amplitude E c , frequency c and Rabi frequency c = d 12 /2 . A weak coherent probe field with the amplitude E p , frequency p and Rabi frequency p = p d 13 /2 is applied between levels |1> and |3>. 2 1 and 2 2 denote the spontaneous decay rates from level |1> to levels |3> and |2>, respectively. J 2 and J 3 are the atomic injection rates for level |2> and |3> respectively; 0 is the atomic exit rate from the cavity. We also assume that th...