用受激光子回波实现四维信息的贮存和读取

USING STIMULATED PHOTO ECHO TO RECONSTRUCT A “FOUR DIMENSION IMAGE”

本文提出受激光子回波来记录和再现“四维(空间+时间)”信息。文中证明了当第一个脉冲E_1(x,y,t)=E_(10)(x,y)δ(t—t_(10))在t_(10)时作用系统,那末第二个脉冲信息E_2(x,y,t)就被第一个脉冲储存在二能级原子系统的偶极子中,当第三个即读取脉冲在t_(30)时作用时,还可以证明,在某些条件下,系统将在t_(40)=t_(30)+(T_(20)—t_(10)时给出第四个脉冲,它就是受激光子回波,并且是信息脉冲E_2(x,y,t)的“四维信息”。这是在t轴上展开的全息图如果第一和第二脉冲互换,在第三个,读取脉冲作用时,第四个回波脉冲将与第一个共轭。如果用稀土离子晶体作贮存材料,激光强度为W/cm^2的量级,在低温条件下,信息可贮存较长时间。

A conceptual suggestion is presented to record and reconstruct a 'four dimension' (space plus time) holographical image by using a stimulated photo echo. It has been proved that if the first pulse E_1(x,y,t)=E_(10)(x,y)δ(t—t_(10)) is applied at time t_(10), then the second pulse E_2(x,y,t)=E_(20)(x,y)f(t—t_(20)) at t_(20)=t_(10)+τ,the second pulse information E_2(x,y,t) was stored in a dipole of two-level atomic system by the first pulse. When a third, read-out pulse E_3(x,y,t)=E_(10)(x,y)δ(t-t_(30)) is applied at t_(30), it can also be proved that under certain contitions, a fourth pulse, the stimulated photo echo, will be given by the system at time t_(40)=t_(30)+(t_(20)-t_(10))=t_(30)+t, which is the 'four dimension image'reconstruction of imformation pulse E_2(x,y,t). This is a holography expanded on the t-axis. If the first and second pulses are reversed, as the third, readout pulse is applied, the fourth echo pulse will be conjugated to the first. If rare-earth ioned crystal is taken as storage material, and the laser intensity to be the magnitude of w/cm2, under the condition of low temperature, the information might be stored in crystal for a long time.