Switchable materials with nanoplasmonics for optical applications

用于光学应用的具有纳米等离子体的可切换材料

• 批准号: RGPIN-2014-04481
• 负责人: Haché, Alain
• 金额: $ 2.11万
• 依托单位: Université de Moncton
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=566551
• 关键词: Switchable; materials; nanoplasmonics; optical; applications

The proposal is in the area of optical beams interacting with switchable and adjustable materials such as vanadium dioxide (VO2) and plasmonic nanoparticles. Parts of my research combine these materials with nanoparticles or uses nanometer-scale patterns to modify the properties. Among the studied materials, VO2 is especially interesting for its ability to change from a dielectric state to a metallic state when heated by only tens of degrees centigrade. This phase transition is accompanied with large changes in refractive indices and absorption coefficients, making optical control possible, with potential applications to photonic devices and metamaterials. This research is not aimed at understanding the growth, fabrication and other such material science aspects of these compounds, but rather understanding their interaction with lasers and other optical beams to exploit these effects for various photonic applications. One of the lead projects aims at controlling accurately the phase of a laser beam that is interacting with a thin film of VO2: the material shows promises for phase modulating devices as thin as 100 nanometers or less. Optical phase control, modulation and shifting is one of the central goals of photonics, with widespread applications in areas like interferometry, optical pulse delay/advance and fast/slow light. We have recently observed that films of VO2 grown under certain conditions in our laboratory exhibit an interesting property at specific wavelengths in the 800-1600 nm range: during phase transition, the phase of the optical beam is changed while keeping the other properties of the beam intact, including polarization and amplitude. Recently, we used a highly sensitive phase measurement technique (developed by our group) to see evidences of accurate phase adjustability through the film. Studies and applications of this effect will be for us a topic of research in the next few years, because it suggests the possibility of phase control over extremely short distances. The phase shift per unit of distance travelled is orders of magnitudes larger than what is typically achieved with eletro-optic materials (e.g. Pockels cells) and liquid crystals. It opens the possibility of highly miniaturized devices for integrated optics, among others. However, there are still many aspects of the problem we need to investigate before these applications are made possible. For example, the wavelength adjustability of the effect and the influence of input polarization have to be theoretically modeled and verified experimentally. Another axis of research involves the enhancement and tailoring of the properties of switchable materials by incorporating metal nanoparticles into them. Gold nanoparticles exhibit plasmon resonances that increase optical absorption at wavelengths that can be tuned by adjusting the size of these particles. With respect to VO2, gold nanoparticles are especially interesting because their resonances occur in the visible spectrum: their absoption in the near infrared is weak compared to that of the VO2 in its metallic state. As a result, nanoparticles can be used to enhance optical pumping and optically-induced switching of the material using visible laser beams. With collaborators, experts in material science, we intend to create hybrid materials with such properties and fully characterize them for photonic applications. For Canada, this research program will have a positive impact by training highly qualified personnel in the economically important areas of optics and photonics. Morover, partnership with industry will be possible because of the applied nature of the project, with potential for new device commercialization.

该提议是在光束与可切换和可调节材料相互作用的领域，如二氧化钒(VO2)和等离子体纳米颗粒。我的部分研究将这些材料与纳米颗粒结合在一起，或者使用纳米级图案来修改特性。在所研究的材料中，VO2特别令人感兴趣的是，当加热几十摄氏度时，它能够从介电状态转变为金属状态。这种相变伴随着折射率和吸收系数的巨大变化，使得光学控制成为可能，在光子器件和超材料中具有潜在的应用前景。这项研究的目的不是为了了解这些化合物的生长、制造和其他材料科学方面的问题，而是为了了解它们与激光和其他光束的相互作用，以利用这些效应用于各种光子应用。其中一个主要项目旨在精确控制与VO2薄膜相互作用的激光束的相位：这种材料有望成为薄至100纳米或更小的相位调制设备。光学相位控制、调制和移位是光子学的核心目标之一，在干涉测量、光脉冲延迟/超前和快慢光等领域有着广泛的应用。我们最近在实验室观察到在一定条件下生长的VO2薄膜在800-1600 nm的特定波长范围内显示出一个有趣的特性：在相变过程中，光束的相位发生变化，而光束的其他特性保持不变，包括偏振和幅度。最近，我们使用了一种高灵敏度的相位测量技术(由我们的团队开发)，通过胶片看到了精确的相位可调的证据。这一效应的研究和应用将是我们未来几年的研究主题，因为它表明了在极短距离内进行相位控制的可能性。每单位行进距离的相移比通常使用电光材料(例如普克尔盒)和液晶实现的相移大几个数量级。它为集成光学等高度小型化的设备提供了可能性。然而，在这些应用程序成为可能之前，我们仍然需要调查问题的许多方面。例如，该效应的波长可调性和输入偏振的影响必须进行理论建模和实验验证。另一个研究方向涉及通过在可切换材料中加入金属纳米颗粒来增强和调整其性能。金纳米颗粒表现出等离子激元共振，可以增加波长上的光吸收，可以通过调节这些颗粒的大小来调节。关于VO2，金纳米粒子特别有趣，因为它们的共振发生在可见光光谱中：与处于金属状态的VO2相比，它们在近红外的吸收较弱。因此，纳米颗粒可以用来增强光学泵浦和利用可见激光对材料进行光诱导开关。我们打算与材料科学方面的合作者和专家合作，创造具有这种性质的杂化材料，并充分表征它们在光子领域的应用。对加拿大来说，这项研究计划将产生积极影响，培养经济重要的光学和光子学领域的高素质人才。此外，由于该项目的应用性质，与业界的合作将是可能的，具有新设备商业化的潜力。