高质量三维胶体光子晶体中慢光速与超光速的实验研究

Experimental investigation of the slow light and superluminal effects in high-quality three-dimensional colloidal photonic crystals

利用飞秒脉冲自相关技术研究了高质量三维胶体光子晶体中的慢光速和超光速效应.实验中使用的胶体光子晶体是采用压力控制的绝热沉积技术(PCIHVD)制备的、由聚苯乙烯小球组成的人工蛋白石结构.由于其中的缺陷和位错密度很低,它们具有很高的通带透过率和陡峭的能带边缘.测量了从通带到带边直至带隙中央群速度的变化,在只有20层左右小球的样品中观察到低至0.43c的慢光速以及高至1.34c的超光速现象.此外,利用时域有限差分(FDTD)方法对短脉冲在三维光子晶体中的群速度进行了数值模拟,并且和实验结果进行了比较.

We investigated by time-of-flight technique the slow light and superluminal effects in high-quality three-dimensional （3D） colloidal photonic crystals （PCs） with opal structure, fabricated by pressure controlled isothermal vertical deposition technique. They produce high transmission in the pass bands and sharp band edges due to low volume density of defects and dislocations. The variation of the group velocity across the short-wavelength band edge was measured. Group velocity as low as 0.43c was observed near the band edge while group velocity as high as 1.34c was found in the band gap. We have also simulated the transportation of ultrashort pulses through 3D PCs and compared the simulation results with the experimental ones.