SEMICONDUCTOR SURFACE PLASMONS: A ROUTE TO TUNABLE THZ DEVICES AND SENSORS

半导体表面等离子体激元：可调谐太赫兹器件和传感器的途径

• 批准号: EP/F026757/1
• 负责人: Euan Hendry
• 金额: $ 41.01万
• 依托单位: UNIVERSITY OF EXETER
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FF026757%2F1
• 关键词: SEMICONDUCTOR; SURFACE; PLASMONS; ROUTE; TUNABLE

Numerous important processes in nature occur at THz frequencies: for example, many rotational and vibrational transitions of various liquid and gas molecules lie within the THz frequency band. In particular, the vibrational breathing modes of many large biomolecules occur at these low frequencies, giving a unique fingerprint in the THz region. While it is clear that the THz band is scientifically very rich, research in this frequency region is limited by technology: the so-called THz gap , occupying a large portion of the electromagnetic spectrum between the infrared and microwave bands, remains relatively unexplored due to a lack of efficient laboratory emitters/detectors and optical components compared to neighboring spectral regions.Here, we explore the potential for developing new THz components and sensors based on semiconductor surface plasmon-polaritons (SPPs). SPPs are electromagnetic waves that propagate along the interface between a conductor and insulator, bound to the surface by the free electrons in the conducting medium. To date, most research investigating the properties of SPPs has been limited to frequencies near metallic plasma frequencies (i.e. at visible and infrared frequencies) where SPP modes are strongly confined to metal surfaces. Semiconductors, with plasma frequencies in the THz range, offer the potential for sustaining SPPs at THz frequencies. Furthermore, semiconductors offer a unique and hugely beneficial advantage over metals: since the surface charge density can be modified by, for example chemical doping, plasma frequencies and SPP properties can be tailored within the THz frequency range. An extension of this is the exciting possibility of all-optical plasmon control, i.e. 'photo-doping' a semiconductor with visible frequency light, so that plasma frequencies may be tuned by a visible frequency light source. Using ultrafast laser sources for this purpose, the properties of THz SPP modes can therefore be tailored and switched on very fast (picosecond) timescales, something that is essential for high-bandwidth and/or time resolved applicationsBorrowing from the well established fields of microwave and optical photonics, and by utilizing the intrinsically tunable nature of semiconductors, we aim to manipulate THz light in new ways using semiconductor SPPs. Initially, we wish to explore the underlying physics of SPPs in the THz frequency range, before looking to develop new applications for this concept. Although there are many areas of potential application for semiconductor SPPs, we will concentrate on two specific areas: firstly, the design of optical components (such as tunable filters, modulators and beam steering systems) based on semiconductor SPPs and secondly, spectroscopy/sensing of biomolecules. The development of new optical components is essential for the continued expansion of scientific research in the THz frequency domain, and we will exploit the wealth of experience currently employed in Exeter to investigate similar applications at microwave and optical frequencies. The second of these potential applications involves what is thought to be possibly the future killer application of THz radiation, i.e. using the fingerprint of large molecules in the THz region for biosensing and biomedical applications. In an analogy to recently developed surface plasmon sensors operating at visible frequencies, employing SPPs for THz sensing will significantly improve sensitivity by concentrating THz radiation in a very thin region close to the semiconductor surface, allowing sensing of very low concentration samples.

自然界中许多重要的过程都发生在太赫兹频率下：例如，各种液体和气体分子的许多旋转和振动跃迁都位于太赫兹频带内。特别是，许多大的生物分子的振动呼吸模式发生在这些低频率，在太赫兹区域提供了一个独特的指纹。虽然很明显太赫兹波段在科学上非常丰富，但在这个频率区域的研究受到技术的限制：由于与相邻的光谱区域相比缺乏有效的实验室发射器/检测器和光学部件，占据红外和微波波段之间的电磁光谱的大部分的所谓的THz间隙仍然相对未被探索。这里，我们探索了开发基于半导体表面等离子体激元（SPP）的新型THz元件和传感器的潜力。SPP是电磁波，其沿着导体和绝缘体之间的界面传播，通过导电介质中的自由电子束缚到表面。到目前为止，大多数研究调查SPP的属性已被限制在金属等离子体频率附近的频率（即在可见光和红外频率），其中SPP模式被强烈地限制在金属表面。等离子体频率在太赫兹范围内的半导体具有在太赫兹频率下维持SPP的潜力。此外，与金属相比，半导体具有独特且巨大的优势：由于表面电荷密度可以通过化学掺杂等方式进行修改，因此等离子体频率和SPP特性可以在THz频率范围内进行调整。其延伸是全光学等离子体激元控制的令人兴奋的可能性，即用可见频率光“光掺杂”半导体，使得等离子体频率可以通过可见频率光源来调谐。为此目的使用超快激光源，THz SPP模式的特性因此可以在非常快（皮秒）的时间尺度上进行定制和切换，这对于高带宽和/或时间分辨应用至关重要。借用微波和光学光子学的成熟领域，并利用半导体的固有可调谐性质，我们的目标是使用半导体SPP以新的方式操纵THz光。最初，我们希望在为这一概念开发新的应用之前，探索太赫兹频率范围内SPP的基本物理学。虽然有许多领域的潜在应用的半导体SPP，我们将集中在两个特定的领域：首先，光学元件（如可调谐滤波器，调制器和光束转向系统）的设计的基础上半导体SPP和第二，光谱/传感的生物分子。新的光学元件的发展是必不可少的科学研究在太赫兹频域的持续扩张，我们将利用丰富的经验，目前在埃克塞特调查在微波和光学频率类似的应用。这些潜在应用中的第二个涉及被认为可能是THz辐射的未来杀手级应用，即使用THz区域中大分子的指纹进行生物传感和生物医学应用。与最近开发的在可见频率下工作的表面等离子体传感器类似，采用SPP进行THz感测将通过将THz辐射集中在靠近半导体表面的非常薄的区域中来显著提高灵敏度，从而允许感测非常低浓度的样品。

项目成果

Multi-modal transmission of microwaves through hole arrays.

• DOI: 10.1364/oe.19.013793
• 发表时间: 2011-07
• 期刊: Optics express
• 影响因子: 3.8
• 作者: J. Edmunds;E. Hendry;A. Hibbins;J. Sambles;I. Youngs

Importance of diffraction in determining the dispersion of designer surface plasmons

• DOI: 10.1103/physrevb.78.235426
• 发表时间: 2008-12-01
• 期刊: PHYSICAL REVIEW B
• 影响因子: 3.7
• 作者: Hendry, E.;Hibbins, A. P.;Sambles, J. R.
• 通讯作者: Sambles, J. R.

Superchiral electromagnetic fields created by surface plasmons in nonchiral metallic nanostructures

• DOI: 10.1103/physrevb.87.085405
• 发表时间: 2013-02-05
• 期刊: PHYSICAL REVIEW B
• 影响因子: 3.7
• 作者: Davis, T. J.;Hendry, E.
• 通讯作者: Hendry, E.

Super-resolution imaging for sub-IR frequencies based on total internal reflection

• DOI: 10.1364/optica.408678
• 发表时间: 2021-01-20
• 期刊: OPTICA
• 影响因子: 10.4
• 作者: Barr, Lauren E.;Karlsen, Peter;Hendry, Euan
• 通讯作者: Hendry, Euan

Role of Dielectric Drag in Polaron Mobility in Lead Halide Perovskites

• DOI: 10.1021/acsenergylett.7b00717
• 发表时间: 2017-11-01
• 期刊: ACS ENERGY LETTERS
• 影响因子: 22
• 作者: Bonn, Mischa;Miyata, Kiyoshi;Zhu, X. -Y.
• 通讯作者: Zhu, X. -Y.