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Graphene-on-Si Hybrid Nanophotonic Integrated Waveguides And Devices

Posted on:2016-05-19Degree:MasterType:Thesis
Country:ChinaCandidate:J J ZhengFull Text:PDF
GTID:2308330464454349Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Silicon photonics is thought to be a promising solution to the next generation chip technology with high speed and reduced power consumption. However, because of the difficulties in realizing all-silicon active optical devices, another material is usually required to assist silicon photonics. Graphene happens to be an ideal CMOS compatible optoelectronic functional material. Considering the two dimensional nature of graphene, it is also necessary to integrate it with silicon photonic devices to enhance its interaction with light. Therefore, the study of both theoretical and experimental aspects of graphene-on-silicon hybrid nanophotonic integrated waveguides and devices is of great importance.The model of graphene optical conductivity could directly lead to many applications such as optical modulators, photodetectors, and plasmonics. The contact between graphene and semiconductors especially silicon is most studied from the perspectives of electronics and free-space optics. This paper reports a polarization-related optically induced transparency (OIT) effect with ultra-low threshold (~0.1 mW) in graphene-on-silicon hybrid nanophotonic integrated waveguides caused by this kind of contact. This OIT effect enables the low-power, all-optical, broadband control and sensing, modulation and switching locally and nonlocally of photonic integrated circuits.The waveguide-integrated graphene photodetector with a Bragg reflector on silicon shorten the length of the light absorption section, so that it, to some extent, solves the problem that waveguide-integrated graphene devices are usually too long to operate at high speed. With an asymmetric metallization scheme, high responsivity of ~0.2 mA W-1 at 1,550 nm under zero bias and broadband photoresponse are observed.Graphene plasmonic waveguides could further enhance the interaction between graphene and light. The tunable pattern-free graphene-on-silicon hybrid nanoplasmonic waveguide on trenched silicon substrate avoids many detrimental edge effects. It shows that this waveguide with nanoscale light confinement, relatively low loss and slowed group velocity enables a significant modulation on the phase shift as well as the propagation loss over a broad mid-infrared band (30 THz~45 THz) by simply applying a single low bias voltage, which is very attractive for realizing ultra-small optical modulators and optical switches for the future ultra-dense photonic integrated circuits. The strong light-matter interaction as well as tunable slow light is also of great interest for many applications such as optical nonlinearities.
Keywords/Search Tags:silicon photonics, graphene, waveguide, heterojunction, photodetector, plasmonics, mid-infrared, two-dimensional materials
PDF Full Text Request
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