线-圆双偏振态光束抽运有机聚合物全光开关

为了有效降低偶氮苯聚合物薄膜全光开关信号的本底,提高全光开关信号的调制深度,利用线偏振光合成圆偏振光的原理,设计了一种新的线-圆双偏振态光束抽运光路。实验用532 nm光作为抽运光,632.8 nm的He-Ne激光作为探测光。532 nm的光先分为功率相等但偏振正交、相位差为π/2奇数倍的两束线偏振光,然后再合成一束抽运光。通过调制其中的一束来实现线偏振与圆偏振抽运光之间的转换,从而实现样品光致双折射的产生与擦除。以掺杂分散红1(DR1)的聚甲基丙烯酸甲酯薄膜(PMMA)为样品进行实验。结果表明,用此光路,样品全光开关信号的调制深度达到92%,远远高于传统的单一线偏振光束抽运光路的实验结果。

All-Optical Switching in Polymer Pumped by a Beam with Linear-Circular Double Polarization

In order to depress the background and increase the modulated depth of the all-optical switching signal, a new experimental setup is designed based on the principle in which a circularly polarized beam can be constructed by two orthogonally linearly polarized ones. This experimental setup contains a probe beam at 632.8 nm and a pump beam at 532 nm with linear-circular polarization. In the experiment, a beam from a semiconductor laser at 532 nm is splitted into two ones with orthogonal polarization and same power, whose phases have a difference of (2n+1)π/2 (n=0,1,2,3,…). The two beams are then recombined into a beam. By modulating one of the two beams at 532 nm, a pump beam with alternately linear-circular polarization can be prepared. With DR1 doped PMMA film as a sample, the experiment shows that the modulated depth in the new setup can reach 92%, which is much larger than that in the traditional method, where a single linearly polarized pump beam is used.