Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716, USA.
Opt Lett. 2010 Nov 1;35(21):3691-3. doi: 10.1364/OL.35.003691.
Free-carrier absorption (FCA) has proven to be an important obstacle in the development of a silicon-based laser; however, FCA may serve as a potential advantage in active silicon-based switches or modulators. In this work, we present FCA modulation in slot waveguides with silicon nanocrystals (Si-ncs) embedded in SiO(2) as the low-index slot material. Slot waveguides were fabricated with and without Si-ncs, and the presence of Si-ncs was shown to increase the pump-induced FCA loss in the waveguides by a factor of 4.5. We modeled the Si-nc material using a four-level rate equation analysis to estimate the excited population of Si-ncs, allowing us to extract a value of 2.6 × 10(-17) cm(2) for the FCA cross section of the Si-nc material.
自由载流子吸收（FCA）已被证明是硅基激光发展的一个重要障碍；然而，FCA 可能成为有源硅基开关或调制器的潜在优势。在这项工作中，我们提出了在具有硅纳米晶体（Si-ncs）嵌入的槽波导中的 FCA 调制，其中 Si-ncs 作为低折射率槽材料。制备了具有和不具有 Si-ncs 的槽波导，并且表明 Si-ncs 的存在将波导中的泵浦诱导的 FCA 损耗增加了 4.5 倍。我们使用四能级速率方程分析对 Si-nc 材料进行建模，以估计 Si-nc 的激发态密度，从而可以提取 Si-nc 材料的 FCA 截面值为 2.6×10(-17)cm(2)。
