文档介绍：Optical Nutationθ=κtr在(v,w)平面内绕u转动-θFIDΔr在(u,v)平面内以角速度Δ绕w转动T2极化强度弛豫的时间常数T1布居弛豫的时间常数,)(cossin0sincos0001000000??????????=?????????????????????=??????????wvuNwvuwvuθθθθθ??????????=???????????????????????=??????????????000000),(1000)cos(e)sin(e0)sin(e)cos(e2222wvutDwvuttttwvuTtTtTtTtΔΔΔΔΔ坐标系绕w轴转动N(θ)是在共振激发Δ=0条件下得到的。在具有非均匀宽化g(Δ)的系统中,当激发光脉冲非常强、系统的电偶极矩μ又很大时,κ>>Δ,θ= ?t ≈κt; Δ～0另外也取决于激发脉冲的频率宽度?2 = Δ2+κ22112?μ?μκhhEE==系统的电偶极矩光场tp1τtp2vu2τPhoton echowt=0w=-1tp1;θ1=π/2u=0v=-1w=0t=tp1-τ-u(t)= e-t/T2sin(Δt)v(t-)=-e-t/T2cos(Δt)w=0t=τ+tp2;加θ2=π脉冲u(τ+tp2)=u(τ)v(τ+tp2)=-v(τ)w=0t=τ-2τ并忽略e-2τ/T2的衰减时:u=0v=1w=0光子回波是光章动-自由感应衰减-光章动-自由感应衰减的结果12skkk?==22τt光子回波的相位匹配条件2/42eTivuτ?=>+<τ<≈T2观察到回波信号强度????????????=??????????=100)(),()(),()()()()(12θτΔθτΔNDNtDtwtvtutr5. 3. 4 5. 3. 4 受激光子回波受激光子回波((Stimulated Photon EchoStimulated Photon Echo------SPE)SPE)原子系统对三个相干光脉冲组成的序列共振激发的瞬态相干响应。θ1= π/2θ2=π/2FIDFIDθ3=π/20τT+τSPEOpticalNutationOpticalNutationOpticalNutationFIDvwt=0u0=v0=0w0=-1θ1=π/2 applied0τT+τut=tp1u=0v=-1w=0tp1τT+τOpticalNutation???????????=??????????????????????=??????????010100010100001wvuπ/2v=-1vwuθ1=π/20τT+τFID??????????Δ?Δ=?????????????????????ΔΔΔ?Δ=????????????????0)cos()sin(0101000)cos()sin(0)sin()cos(222222ττττττττττττTTTTTTwvueeeeee0)()cos()()sin(22=Δ?=Δ==??ττττττττwvTTee)u(tΔτΔτΔτΔτvuwtp2tp1tp30τT+τOpticalNutation???????????=?????????????????????=??????????)(0)(0)()(010100001ττττvuvuwvu)cos(e)(0)()sin(e)u(t222τττττΔ==Δ=+=??TTptwtvtt时:tp2绕u顺时针转动π/2uwΔτΔτΔτΔτvuΔτΔτΔτΔτw()1e)cos(e121//?+Δ=+???TTTTTTwτττuw0τT+τFIDt=τ+Tu≈0v≈0w=w(t+τ)第二个脉冲的自由感应衰减时间足够长,T1>T>>T2u、v迅速衰减为零,w的衰减慢些。发生自由感应衰减,当t~T1比较大时当t<<T1时00e)cos(e00e)cos(e)sin()sin(e)sin()cos(e1)cos(e0)sin(e000)cos(e)sin(e0)sin(e)cos(e1)/(2////)()(/2121121222212222≈>>??????????+Δ=??????????+ΔΔΔ?ΔΔ=??????????+ΔΔ??????????ΔΔΔ?Δ=??????????+???????+?+????????TTTTTTTTTTTTTTTTTTTTTTTTTTTTeTTTTeTTTTwvu时,当ττττττττττττ11122//0/000/00/ee1e)()]cos()sin([e)]sin()cos([eTtTtTteqeqTtTt?????+=+?+=Δ+Δ=Δ?Δ=??????????=???????????????????????=??????????????000000