Silicon is incredibly well-studied as an electronic material. Since the out-migration of William Noyce, Gordon Moore, and the rest of the original Fairchild Semiconductor class from Shockley Semiconductor, silicon has only grown in prominence. Untold billions have been expended on research, development, and manufacture, and now silicon is perhaps the most well-controlled commercial material on Earth. For all that, the use of silicon as a mechanical material, though envisioned in the late 1950s, largely became viable only after the advent of large-scale silicon processing for microelectronics. As an optical material, silicon also has a long pedigree, with most of the positive focus on its excellent optical transparency and the enormous potential for improvement residing in its lack of effective emission.ududThis thesis concerns an alternate route to the generation of light in silicon: the nonlinear route. Resonant elements play a critical role in making this viable. The ability to build up optical intensity in the confined volume of a microresonator reduces the input power required to achieve a given energy density. Silicon also has certain excellent nonlinear properties: a large Raman gain coefficient, for example, and an appreciable Kerr effect. Unfortunately, silicon also exhibits significant two-photon absorption (TPA) in the convenient telecommunications wavelength bands. As such, the build-up of optical energy in silion may also be accompanied by a build-up of TPA-induced free-carrier populations. These populations may serve to limit the efficiency of nonlinear processes or to generate additional nonlinear behavior in their interactions with optical fields.ududThus two important stepping-stones on the way to the low-power,low-footprint use of silicon as an optical material are: the need to reduce optical losses in the optical elements, and to reduce or modify the populations of free carriers generated in the nonlinear optics regime. This thesis will present design considerations of, fabrication techniques developed for, and characterization techniques of high-Q silicon microresonators. In the course of this work, we have created silicon microdisk resonators with quality factors as high as 5×10^6, and high-Q silicon microdisks with free-carrier lifetimes in the deep subnanosecond regime (Q=5–6×10^5 and carrier lifetimes ≤ 240 ps). These results, with no indication that higher quality factors or shorter carrier lifetimes are not possible in similar structures, indicate that coherent, CW optical generation in passive silicon microresonators is approaching feasibility.ud
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机译:硅作为一种电子材料的研究非常深入。自从William Noyce,Gordon Moore和其余的最初的Fairchild Semiconductor类从Shockley Semiconductor迁出以来,硅的重要性一直在增长。在研究,开发和制造上已经花费了数十亿美元,现在硅也许是地球上控制最严格的商业材料。尽管如此,尽管在1950年代末期就设想到将硅用作机械材料,但在大规模用于微电子技术的硅加工问世之后,硅才成为可行的方法。作为一种光学材料,硅还具有很长的血统,其主要关注点在于其出色的光学透明性和缺乏有效发射的巨大改进潜力。 ud ud硅中的光:非线性路径。共振元素在使其可行中起着至关重要的作用。在微谐振器的有限体积内建立光强度的能力降低了实现给定能量密度所需的输入功率。硅还具有某些出色的非线性特性:例如较大的拉曼增益系数和明显的Kerr效应。不幸的是,硅在方便的电信波段中也表现出显着的双光子吸收(TPA)。因此,硅中光能的积累也可能伴随着TPA诱导的自由载流子群体的积累。这些种群可能会限制非线性处理的效率,或者在它们与光场的相互作用中产生额外的非线性行为。 ud ud因此,硅作为低功耗,低占用空间的途径中有两个重要的垫脚石。光学材料是:需要减少光学元件中的光学损耗,以及减少或修改在非线性光学系统中产生的自由载流子的数量。本文将介绍高Q硅微谐振器的设计考虑,开发的制造技术和表征技术。在这项工作的过程中,我们创建了质量因子高达5×10 ^ 6的硅微盘谐振器,并在深亚纳秒范围内(Q = 5–6×10 ^ 5,载波寿命≤240 ps)。这些结果没有表明在类似结构中不可能获得更高的品质因数或更短的载流子寿命,这表明无源硅微谐振器中相干的CW光生成正在接近可行性。
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