实现光强精细调制的共轭聚合物波导电光调制器

A conjugated polymer waveguide electro-optic modulator for accurate light inten sity modulation

摘要:

提出了一 种新型的聚合物波导电光调制器,同时利用了聚合物材料的Pockels效应和Kerr效应,在不 增加调制电压的 情况下,通过引入直流偏压增加了调制器的调制度,调制深度随着直流偏压的增加而增加 。采用峰-峰值 9.9V的调制电压、100V的直流偏压,利用po ckels电光系数γ₃₃仅 为4．052×10－14 m/V和二次电光 系数S₃₃为6．889×10－21 m²/V 2的聚合物材料制备了波导电光调制器,实现了7.54%的调制度。如果 采用具有 更高的分子极化率及电光系数的非线性共轭聚合物材料,可期待在更低的直流偏压和工作电 压情况下,得 到更高的调制深度。调制器的工作面积大,可以实现大面积光斑的调制。本文的聚合物波导 电光调制器适用于 激光脉冲喷丸强化与成形技术,通过调整调制器的直流工作偏压,能够实现激光光斑能量的 精细调节。

Abstract:

Some conjugated polymers,which have the delocalization of p-electrons and the push-pull structure along the main conjugated chain,exhibit second and third order nonlinear optical res ponses after corona-poling.An electro-optic polymer waveguide modulator based on both Pockels and Kerr effect s has been demonstrated.By applying a dc bias,the modulation depth is improved with the dc bias at a fixed m odulation voltage.The proposed modulator achieves a 7.54% modulation depth with 9.9V p.p modulation triangular voltage and 100V dc bias at 100kHz by employing a conjugated polymer,poly (9,9-dioctyl-2,7-fluorene-co -benzo [c][1,2,5] thiadiazole-co-9-hexyl-3,6-carbazole),where the Pockels coefficient comp onent is only γ₃₃＝4．052×10－14 m/V an d the second ary electro-optic coefficient is S₃₃＝6．889×10 －21 m²/V².A higher modulation depth could be realized at a lower dc bias with a lower modula tion voltage by using a higher molecular polarizability and electro-optical coefficient conjugated polymer.Be cause of the big working area,the modulation of the large light spot could be achieved.In the laser pulse shot pe ening and forming technique, accurate light intensity modulation can be realized by adjusting the dc bias v oltage of the modulator.