We study high order harmonics generation (HHG) in crystalline silicon and diamond subjected to near and mid-infrared laser pulses. We employ time-dependent density functional theory and solve the time-dependent Kohn-Sham equation in the single-cell geometry. We demonstrate that clear and clean HHG spectra can be generated with careful selection of the pulse duration. In addition, we simulate dephasing effects in a large silicon super-cell through displacement of atomic positions prepared by a molecular dynamics simulation. We compare our results with the previous calculations by Floss et al. [arXiv:1705.10707] [Phys. Rev. A 97, 011401(R) (2018)] on Diamond at 800 nm and by Tancogne-Dejean et al. [arXiv:1609.09298] [Phys. Rev. Lett. 118, 087403 (2017)] on Si at 3000 nm.
Second harmonic generation and birefringence of some ternary pnictide semiconductors
用第一性原理研究了具有黄铜矿结构的三元磷属元素化物半导体ABC $_2$（A = Zn，Cd; B = Si，Ge; C = As，P）的双折射和频率相关的二次谐波产生系数.我们表明，一个简单的经验观察，一个较小的值的差距与较大的值的SHG是定性的真实。然而，在带隙和二次谐波之间并没有发现简单的幂次反比关系，相反，非线性响应的真实值是不同带内和带间项之间非常微妙的平衡的结果。
Efficient ab-initio method for the calculation of frequency dependent non-linear optical response in semiconductors: application to second harmonic generation
Nonlinear optics from an ab-initio approach by means of the dynamical Berry phase: Application to second- and third-harmonic generation in semiconductors
Theory and design of In$_{x}$Ga$_{1-x}$As$_{1-y}$Bi$_{y}$ mid-infrared semiconductor lasers: type-I quantum wells for emission beyond 3 $μ$m on InP substrates
我们提出了一个理论分析和优化的中红外半导体激光器的属性和性能的基础上稀释bismide合金在$_{x}$ Ga $_{1-x}$作为$_{1-y}$ Bi $_{y}$，生长在传统的（001）InP衬底。在这种四元合金中独立地改变外延应变和发射波长的能力为带结构工程提供了显著的范围。我们的计算表明，基于压缩应变的In $_{x}$ Ga $_{1-x}$ As $_{1-y}$ Bi $_{y}$量子阱（QW）的结构可以容易地实现在3 - 5 $μ$ m范围内的发射波长，并且这些QW具有大的I型带偏移。因此，这些结构具有克服通常与这种应用丰富但技术上具有挑战性的波长范围相关联的许多限制的潜力。通过考虑具有（i）固定QW厚度和可变应变，以及（ii）固定应变和可变QW厚度的结构，我们将特性和性能的关键趋势量化为合金成分，结构特性和发射波长的函数，并在此基础上确定实现实际应用的优化器件的路线。我们的分析表明，简单的激光器结构-将在$_{x}$镓$_{1-x}$作为$_{1-y}$铋$_{y}$量子阱和无应变三元在$_{0.53}$镓$_{0.47}$作为障碍-这是与既定的外延生长兼容，提供了一条路线，以实现基于InP的中红外二极管激光器。
Optical beam-induced scattering mode of mid-IR laser microscopy: a method for defect investigation in near-surface and near-interface regions of bulk semiconductors
The mid-infrared (MIR), far-infrared (FIR) to terahertz (THz) frequencies are the least developed parts of the electromagnetic spectrum for applications. Traditional semiconductor technologies like laser diodes and photodetectors are successful in the visible light range, but are still confronted with great challenges when extended into the MIR/FIR/THz range. In this paper, we demonstrate that topological insulators (TIs), especially those with Mexican-hat band structure (MHBS), provide a route to overcome these challenges. The optical responses of MHBS TIs can be one to two orders of magnitud…
Plasmonic-cavity Modulator for the Mid-IR with a Semi-transparent and Nonlinear Heavily-doped Semiconductor Mirror
Istituto Italiano di Tecnologia（意大利理工学院）；Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche（国家研究委员会光子和纳米技术研究所）；University of Luxembourg（卢森堡大学）；Institute for Advanced Studies, University of Luxembourg Campus Belval（卢森堡大学贝尔瓦尔校区高等研究院）；Centre de Nanosciences et de Nanotechnologies (C2N), CNRS UMR 9001, Universit´e Paris-Saclay（巴黎萨克雷大学CNRS 9001联合实验室纳米科学与纳米技术中心）
By independently engineering strain and composition, this work demonstrates and investigates direct band gap emission in the mid-infrared range from GeSn layers grown on silicon. We extend the room-temperature emission wavelength above ~4.0 μm upon post-growth strain relaxation in layers with uniform Sn content of 17 at.%. The fundamental mechanisms governing the optical emission are discussed based on temperature-dependent photoluminescence, absorption measurements, and theoretical simulations. Regardless of strain and composition, these analyses confirm that single-peak emission is always ob…
Recently, atomically thin PdSe$_2$ semiconductors with rare pentagonal Se-Pd-Se monolayers were synthesized and were also found to possess superior properties such as ultrahigh air stability, and high carrier mobility, thus offering a new family of two-dimensional (2D) materials for exploration of 2D semiconductor physics and for applications in advanced opto-electronic and nonlinear photonic devices. In this work, we systematically study the nonlinear optical (NLO) responses [namely, bulk photovoltaic effect (BPVE), second-harmonic generation (SHG) and linear electric-optic (LEO) effect] of n…
Second harmonic generation (SHG) is a nonlinear optical response arising exclusively from broken inversion symmetry in the electric-dipole limit. Recently, SHG has attracted widespread interest as a versatile and noninvasive tool for characterization of crystal symmetry and emerging ferroic or topological orders in quantum materials. However, conventional far-field optics is unable to probe local symmetry at the deep subwavelength scale. Here, we demonstrate near-field SHG imaging of 2D semiconductors and heterostructures with the spatial resolution down to 20 nm using a scattering-type nano-o…
Strain engineering has been a ubiquitous paradigm to tailor the electronic band structure and harness the associated new or enhanced fundamental properties in semiconductors. In this regard, semiconductor membranes emerged as a versatile class of nanoscale materials to control lattice strain and engineer complex heterostructures leading to the development of a variety of innovative applications. Herein we exploit this quasi-two-dimensional platform to tune simultaneously the lattice parameter and bandgap energy in group IV GeSn semiconductor alloys. As Sn content is increased to reach a direct…
Recent advancements in the generation of mid-infrared and terahertz laser pulses have enabled us to observe strong-field driven non-perturbative high-harmonic generation (HHG) from semiconductors, dielectrics, and semimetals. HHG has added another dimension to time-resolved ultrafast electron dynamics in materials with unprecedented temporal resolution. Present thesis discusses how HHG is an emerging method to probe static and dynamical properties in two-dimensional materials. In this thesis, two-dimensional materials with hexagonal symmetry are studied. We have demonstrated that the high-harm…
