CAJ | 학술논문

利用G C Valley的准连续光(Quasi-cw)近似模型,研究了短脉冲激光(纳秒ns量级)在光伏光折变材料LiNbO_3晶体中写入和擦除光折变光栅的过程,给出了空间电荷场随时间变化的表达式.理论研究表明,空间电荷场的形成和擦除与两个时间参量有关,在考虑或者不考虑光生伏打效应两种情况下,这两个参量随擦除光强的变化有基本相同的变化规律,光栅的写入和擦除有相同的结果.同样,擦除一个光栅所需的光能量在两种情况下也有相同的结果.因此,在短脉冲光入射光折变晶体材料情况下,考虑光生伏打效应与不考虑光伏效应,对短脉冲光在光折变LiNbO_3晶体中写入和擦除光栅基本没有影响.
이용G C Valley적준련속광(Quasi-cw)근사모형,연구료단맥충격광(납초ns량급)재광복광절변재료LiNbO_3정체중사입화찰제광절변광책적과정,급출료공간전하장수시간변화적표체식.이론연구표명,공간전하장적형성화찰제여량개시간삼량유관,재고필혹자불고필광생복타효응량충정황하,저량개삼량수찰제광강적변화유기본상동적변화규률,광책적사입화찰제유상동적결과.동양,찰제일개광책소수적광능량재량충정황하야유상동적결과.인차,재단맥충광입사광절변정체재료정황하,고필광생복타효응여불고필광복효응,대단맥충광재광절변LiNbO_3정체중사입화찰제광책기본몰유영향.
Based on Valley's quasi-cw approximation,the writing and erasing of gratings in materials exhibiting bulk photovoltaic effect on illumination with short light pulses (such as ns pulses) is investigated.The expression of space-charge field is given out in the paper with two time constants τ_(pa) and τ_(pb).When considering and not considering the photovoltaic effect,the diagrams of the two time constants as a function of irradiance in units of 1/(sτ_R) are the same.The energy required to erase a grating to 1/e of its initial value is also studied in the two cases and the two results are also the same.In the case of short light pulses irradiance,photovoltaic effect has no effect on the writing and erasing photorefractive gratings in the LiNbO_3 crystal.