哈佛大學(xué)電子工程科研

以計劃申請美國名校電子工程類相關(guān)專業(yè)的大學(xué)生為主

科研主題： 

photonic crystals, one-dimensional photonic crystals, Photonic band gap, etc.

科研概述：

光子晶體是指具有光子帶隙（PhotonicBand-Gap,簡稱為PBG）特性的人造周期性電介質(zhì)結(jié)構(gòu)，有時也稱為PBG光子晶體結(jié)構(gòu)。所謂的光子帶隙是指某一頻率范圍的波不能在此周期性結(jié)構(gòu)中傳播，即這種結(jié)構(gòu)本身存在“禁帶”。

光子晶體（Photonic Crystal）是在1987年由S.John和E.Yablonovitch分別獨(dú)立提出，是由不同折射率的介質(zhì)周期性排列而成的人工微結(jié)構(gòu)。光子晶體即光子禁帶材料，從材料結(jié)構(gòu)上看，光子晶體是一類在光學(xué)尺度上具有周期性介電結(jié)構(gòu)的人工設(shè)計和制造的晶體。與半導(dǎo)體晶格對電子波函數(shù)的調(diào)制相類似，光子帶隙材料能夠調(diào)制具有相應(yīng)波長的電磁波---當(dāng)電磁波在光子帶隙材料中傳播時，由于存在布拉格散射而受到調(diào)制，電磁波能量形成能帶結(jié)構(gòu)。能帶與能帶之間出現(xiàn)帶隙，即光子帶隙。所具能量處在光子帶隙內(nèi)的光子，不能進(jìn)入該晶體。光子晶體和半導(dǎo)體在基本模型和研究思路上有許多相似之處，原則上人們可以通過設(shè)計和制造光子晶體及其器件，達(dá)到控制光子運(yùn)動的目的。光子晶體(又稱光子禁帶材料)的出現(xiàn)，使人們操縱和控制光子的夢想成為可能。

科研計劃：

In recent years, artificial optical materials and structures enabled the observation of various new optical effects and experiments. For example, photonic crystals are able to inhibit the propagation of certain light frequencies and provide the unique ability to guide light around very tight bends and along narrow channels. On the other hand, the high field strengths in optical microresonators lead to nonlinear optical effects that are important for future integrated optical networks. This chapter explains the basic underlying principles of these novel optical structures. For a more detailed overview the reader is referred to review articles and books listed in the references.

Session 1: Introduction to photonic crystals

SEPT1: Photonic crystals are a marriage of solid-state physics and electromagnetism. Crystal structures are citizens of solid-state physics, but in photonic crystals the electrons are replaced by electromagnetic waves. Accordingly, we present the basic concepts of both subjects before launching into an analysis of photonic crystals.

Session2: Basic concepts

SEPT 2: presents some basic concepts of solid-state physics and symmetry theory as they apply to photonic crystals. It is common to apply symmetry arguments to understand the propagation of electrons in a periodic crystal potential. Similar arguments also apply to the case of light propagating in a photonic crystal. We examine the consequences of translational, rotational, mirror-reflection, inversion, and time-reversal symmetries in photonic crystals, while introducing some terminology from solid-state physics.

Session3: Introduction to one-dimensional photonic crystals

SEPT 3: To develop the basic notions underlying photonic crystals, we begin by reviewing the properties of one-dimensional photonic crystals. we will see that one-dimensional systems can exhibit three important phenomena: photonic band gaps, localized modes, and surface states. Because the index contrast is only along one direction, the band gaps and the bound states are limited to that direction. Nevertheless, this simple and traditional system illustrates most of the physical features of the more complex two- and three-dimensional photonic crystals, and can even exhibit unidirectional reflection.

Session4: Introduction to two-dimensional photonic crystals

SEPT 4: In this session, we discuss the properties of two-dimensional photonic crystals, which are periodic in two directions and homogeneous in the third. These systems can have a photonic band gap in the plane of periodicity. By analyzing field patterns of some electromagnetic modes in different crystals, we gain insight into the nature of band gaps in complex periodic media. We will see that defects in such two-dimensional crystals can localize modes in the plane, and that the faces

of the crystal can support surface states.

Session5: Introduction to three-dimensional photonic crystals

SEPT 5: addresses three-dimensional photonic crystals, which are periodic along three axes. It is a remarkable fact that such a system can have a complete photonic band gap, so that no propagating states are allowed in any direction in the crystal. The discovery of particular dielectric structures that possess a complete photonic band gap was one of the most important achievements in this field. These crystals are sufficiently complex to allow localization of light at point defects and propagation along linear defects.

Session6: Photonic band gap

SEPT 6: Many periodic-waveguide structures are possible. It will turn out that, regardless of the geometry, all such structures exhibit common phenomena: they have a form of photonic band gap along their periodic direction, and can confine light in the other directions by the principle of index guiding

Session7: Design of two-dimension a photonic crystals

SEPT 7: The session will examine different forms of such hybrid systems, all of which use a combination of periodicity and other mechanisms to confine light in three dimensions session will look at periodic planar waveguides known as photonic-crystal slabs, which use two-dimensional periodicity combined with vertical index-guiding.

Session8: Lumerical FDTD

SEPT8: Lumerical FDTD is an important research tool for designing photonic crystals. Employing the industry-proven finite-difference time-domain (FDTD) method, FDTD Solutions empowers device and components designers to confront challenging optical design problems. Rapid prototyping and highly-accurate simulations reduce reliance upon costly experimental prototypes, leading to quicker assessment of design concepts and reduced product development costs.

Session9: Design of three-dimension a photonic crystals                      

SEPT9: The session will examine different forms of such hybrid systems, all of which use a combination of periodicity and other mechanisms to confine light in three dimension session will look at periodic planar waveguides known as photonic-crystal slabs, which use two-dimensional periodicity combined with vertical index-guiding.

Session10: Designing Photonic Crystals for Applications I

SEPT10: We have expended a great deal of effort to understand the different ways in which photonic crystals can reflect and trap light, thereby forming mirrors, waveguides, and resonant cavities. These three components are themselves very useful, especially because they can have unusual properties that are not shared by their predecessors made from unstructured materials. Now, however, we will examine some useful ways in which these components can be combined. We will see that there are simple universal behaviors that result from such combinations, regardless of the specific geometric structure, which are captured by the formalism of temporal coupled-mode theory. This allows us to design devices easily from first principles, and only afterwards determine the quantitative details from a small number of variables: the symmetries, frequencies, and decay rates of the resonant cavities. We will provide examples of filters, which only transmit light within a specified frequency band; bends, which guide light around a sharp corner; and splitters, which divide a waveguide into two. Finally, we will consider further the applications of nonlinear materials.

Session11: Designing Photonic Crystals for Applications II

SEPT11: With a suitable nonlinear material, the photonic-crystal filter can act asan optical “transistor.”For simplicity, most of our examples will be drawn from two dimension a systems. The ideas generalize easily to the cases of one- and three-dimensional dealing with the impact of losses on device performance; for this purpose we will consider hybrid structures such as those of chapter 7, where radioactive losses inevitably arise for resonant cavities.

科研亮點(diǎn)：

1. 進(jìn)入美國名校實(shí)驗(yàn)室/科研組，接觸尖端科學(xué)

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3. 獲得導(dǎo)師推薦信和科研證書

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科研收獲：

1. 科研完成時，學(xué)生將會全面了解物理光學(xué)&電子工程領(lǐng)域基本知識和最新進(jìn)展。

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