Generating Optical Birefringence and Chirality in Silicon Nanowire Dimers

Zhao, Xiaohui; Alizadeh, Mohammad Hossein; Reinhard, Bjoern M.

doi:10.1021/acsphotonics.7b00501

Cited by 17 publications

(18 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Numerically, the NW waveguide modes have been vastly investigated [13][14][15][16][17]. The properties of the confined fields have also recently lead to some new prospects in spin angular momentum formation [18], and near chiral field manipulation [19,20]. Finally, semiconductor NW hybridization with metallic layers has recently shown effects such as circular dichroism [21].…”

Section: Introductionmentioning

confidence: 99%

Resonant Absorption in GaAs-Based Nanowires by Means of Photo-Acoustic Spectroscopy

et al. 2018

View full text Add to dashboard Cite

Semiconductor nanowires made of high refractive index materials can couple the incoming light to specific waveguide modes that offer resonant absorption enhancement under the bandgap wavelength, essential for light harvesting, lasing and detection applications. Moreover, the non-trivial ellipticity of such modes can offer near field interactions with chiral molecules, governed by near chiral field. These modes are therefore very important to detect. Here, we present the photo-acoustic spectroscopy as a low-cost, reliable, sensitive and scattering-free tool to measure the spectral position and absorption efficiency of these modes. The investigated samples are hexagonal nanowires with GaAs core; the fabrication by means of lithographyfree molecular beam epitaxy provides controllable and uniform dimensions that allow for the excitation of the fundamental resonant mode around 800 nm. We show that the modulation frequency increase leads to the discrimination of the resonant mode absorption from the overall absorption of the substrate. As the experimental data are in great agreement with numerical simulations, the design can be optimized and followed by photo-acoustic characterization for a specific application.

show abstract

Section: Introductionmentioning

confidence: 99%

Resonant Absorption in GaAs-Based Nanowires by Means of Photo-Acoustic Spectroscopy

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Structures under investigation are hexagonal Si NWs, that can be patterned on Si substrate, e.g., by means of conventional electron beam lithography [ 32 , 33 ]. In what follows, we use a commercial-grade simulator based on the 3D Finite Difference Time Domain (FDTD) method by Lumerical [ 34 ] to simulate complex electromagnetic fields in the Si NW array, and later extract C factor; more details are given in Section 4 .…”

Section: Resultsmentioning

confidence: 99%

“…In [ 26 ] we investigated GaAs NW modes at ~800 nm, where we showed that for linearly polarized excitation, the near-field chirality cancels out and the additional symmetry breaking (e.g., the asymmetric layer of Au) must be introduced in order to have a C of prevalently one sign. In [ 32 ], NW dimers are used to induce the optical chirality and the hotspots of high C enhancement. Here, we show that under circularly polarized (CP) excitation, achiral NW structure can generate the enhanced chirality in the NW border vicinity, without the additional symmetry breaking which would complicate the processing of a perspective device.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Near-Field Chirality in Periodic Arrays of Si Nanowires for Chiral Sensing

Petronijevic

Sibilia

2019

Molecules

View full text Add to dashboard Cite

Nanomaterials can be specially designed to enhance optical chirality and their interaction with chiral molecules can lead to enhanced enantioselectivity. Here we propose periodic arrays of Si nanowires for the generation of enhanced near-field chirality. Such structures confine the incident electromagnetic field into specific resonant modes, which leads to an increase in local optical chirality. We investigate and optimize near-field chirality with respect to the geometric parameters and excitation scheme. Specially, we propose a simple experiment for the enhanced enantioselectivity, and optimize the average chirality depending on the possible position of the chiral molecule. We believe that such a simple achiral nanowire approach can be functionalized to give enhanced chirality in the spectral range of interest and thus lead to better discrimination of enantiomers.

show abstract

“…The oligomer waveguide modes can be understood to arise due to the overlapping and interaction of monomer modes in the individual nanowires, somewhat analogous to the hybridization model for resonant excitations in nanoparticle oligomers [10]. To the best of our knowledge, the modal properties of nanowire oligomer waveguide modes have not been previously reported or their hybridization origin discussed, at least beyond recognizing coupled HE 11 modes leading to birefringence in nanowire dimers [11,12]. Here, we will show that InGaAs nanowire dimers and tetramers on a GaAs substrate (assuming bottom-up growth) emitting in the telecommunication C band wavelength range can, indeed, possess modes that exhibit improved modal confinement factor and modal reflectivities compared to the monomer modes from which they originate.…”

Section: Introductionmentioning

confidence: 95%

Nanowire Oligomer Waveguide Modes towards Reduced Lasing Threshold

2020

View full text Add to dashboard Cite

Semiconductor nanowires offer a promising route of realizing nanolasers for the next generation of chip-scale optoelectronics and photonics applications. Established fabrication methods can produce vertical semiconductor nanowires which can themselves act both as a gain medium and as a Fabry–Pérot cavity for feedback. The lasing threshold in such nanowire lasers is affected by the modal confinement factor and end facet reflectivities, of which the substrate end reflectivity tends to be limited due to small refractive index contrast between the nanowire and substrate. These modal properties, however, also depend strongly on the modal field profiles. In this work, we use numerical simulations to investigate waveguide modes in vertical nanowire oligomers (that is, arrangements of few vertical nanowires close to each other) and their modal properties compared to single nanowire monomers. We solve for the oligomer waveguide eigenmodes which are understood as arising from interaction of monomer modes and further compute the reflectivity of these modes at the end facets of the nanowires. We consider either the nanowires or an additional coating layer as the gain medium. We show that both types of oligomers can exhibit modes with modal properties leading to reduced lasing threshold and also give directions for further research on the topic.

show abstract

Generating Optical Birefringence and Chirality in Silicon Nanowire Dimers

Cited by 17 publications

References 58 publications

Resonant Absorption in GaAs-Based Nanowires by Means of Photo-Acoustic Spectroscopy

Resonant Absorption in GaAs-Based Nanowires by Means of Photo-Acoustic Spectroscopy

Enhanced Near-Field Chirality in Periodic Arrays of Si Nanowires for Chiral Sensing

Nanowire Oligomer Waveguide Modes towards Reduced Lasing Threshold

Contact Info

Product

Resources

About