Derivative-free Optimization for Optical Chirality Enhancement

G. Pellegrini, F. Michelotti, A. Occhicone, M. Celebrano, M. Finazzi, and P. Biagioni

Chirality (In Nature)

Dipartimento di Fisica - Università di Pavia

Eosam 2024, 9-13 September 2024, Naples, Italy

Molecules

DNA

Proteins

Left Enantiomer

Right Enantiomer

Probing Chirality with Electromagnetic Fields

Dipartimento di Fisica - Università di Pavia

TM Polarization

Left = TE + i*TM

Right = TE - i*TM

Optical Rotation (OR)

Circular Dichroism (CD)

\[\mathrm{CD = A_{R}-A_{L}}\]

\[\mathrm{\psi = \Delta \theta} \]

TE Polarization

Eosam 2024, 9-13 September 2024, Naples, Italy

Superchiral Light: Enhancing Chiral Light-Matter Interaction

Dipartimento di Fisica - Università di Pavia

Finazzi, Marco, et al. "Quasistatic limit for plasmon-enhanced optical chirality." Physical Review B 91.19 (2015): 195427.

Schäferling, Martin. "Chiral nanophotonics." Springer Series in Optical Sciences 205 (2017): 159.

C = -\frac{\varepsilon_{0} \omega}{2} Im(\mathrm{\mathbf{E}}^{*} \cdot \mathrm{\mathbf{B}})

Mattioli, F. et al. Plasmonic Superchiral Lattice Resonances in the Mid-Infrared. ACS Photonics 7, 2676–2681 (2020)

Local optical chirality

Optical chirality enhancement

\frac{C}{C_{\mathrm{CPL}}}

Eosam 2024, 9-13 September 2024, Naples, Italy

Superchiral Light with a Planar Geometry

Dipartimento di Fisica - Università di Pavia

  • Large optical chirality enhancement

  • Uniformity over large areas

  • Optical chirality switching

  • Broadband operation

  • Flat spectral response

Planar Geometries as an Ideal Candidate

Eosam 2024, 9-13 September 2024, Naples, Italy

A Planar Geometry for Superchiral Light: Take 1

Dipartimento di Fisica - Università di Pavia

TE ± i*TM

TE ± i*TM

Surface Plasmon

Eosam 2024, 9-13 September 2024, Naples, Italy

A Planar Geometry for Superchiral Light: Take 2

Dipartimento di Fisica - Università di Pavia

Bloch Surface Waves (BSW)

TE ± i*TM

TE ± i*TM

\[ \mathrm{ (\lambda_{TM},\theta_{TM})} \]

\[ \mathrm{ (\lambda_{TE},\theta_{TE})} \]

\[ \mathrm{ (\lambda_{TM},\theta_{TM})} \neq \mathrm{ (\lambda_{TE},\theta_{TE})} \]

Eosam 2024, 9-13 September 2024, Naples, Italy

Aligning the Dispersion Relations

Dipartimento di Fisica - Università di Pavia

\[ \mathrm{ (\lambda_{TM},\theta_{TM})} \neq \mathrm{ (\lambda_{TE},\theta_{TE})} \]

Eosam 2024, 9-13 September 2024, Naples, Italy

\[ \mathrm{ (\lambda_{TM},\theta_{TM})} = \mathrm{ (\lambda_{TE},\theta_{TE})} \]

A Hard Earned Solution: SiO2-Ta2O5 1PDC

Dipartimento di Fisica - Università di Pavia

  • Pellegrini, Giovanni, et al. "Chiral surface waves for enhanced circular dichroism." Physical Review B 95.24 (2017): 241402.

  • Pellegrini, Giovanni, et al. "Surface‐enhanced chiroptical spectroscopy with superchiral surface waves." Chirality 30.7 (2018): 883-889.

  • Pellegrini, Giovanni, et al. "Superchiral surface waves for all-optical enantiomer separation." The Journal of Physical Chemistry C 123.46 (2019): 28336-28342.

Eosam 2024, 9-13 September 2024, Naples, Italy

The Lazy Man Solution: Multi Objective Optimization

Dipartimento di Fisica - Università di Pavia

Eosam 2024, 9-13 September 2024, Naples, Italy

\omega_1 \, (\lambda_1)
\omega_2 \, (\lambda_2)
\begin{cases} C(\omega_1) = -\frac{\varepsilon_{0} \omega_1}{2} Im(\mathrm{\mathbf{E}}^{*} \cdot \mathrm{\mathbf{B}}) \\ C(\omega_2) = -\frac{\varepsilon_{0} \omega_2}{2} Im(\mathrm{\mathbf{E}}^{*} \cdot \mathrm{\mathbf{B}}) \end{cases}

Maximize \(C \)

@ \(\omega_1\) and \(\omega_2\)

@ the 1DPC Surface

SIMULTANEOUSLY!!! 

Band Alignement

Genetically Evolved (NSGAII) SiO2-Ta2O5 1PDC

Dipartimento di Fisica - Università di Pavia

Eosam 2024, 9-13 September 2024, Naples, Italy

SiO\(_{2}\)

Ta\(_{2}\)O\(_{5}\)

Vilfredo Pareto

Genetically Evolved Cellulose-Polystyrene 1PDC

Dipartimento di Fisica - Università di Pavia

Eosam 2024, 9-13 September 2024, Naples, Italy

Polystyrene

Cellulose

Genetically Evolved Low Contrast 1PDC

Dipartimento di Fisica - Università di Pavia

High Contrast

Ta\(_{2}\)O\(_{5}\)

SiO\(_{2}\)

SiO\(_{2}\)

SiO\(_{x}\)

Low Contrast

Eosam 2024, 9-13 September 2024, Naples, Italy

High vs Low Dielectric Contrast: Zooming in the Bands

Dipartimento di Fisica - Università di Pavia

High Contrast

Ta\(_{2}\)O\(_{5}\)

SiO\(_{2}\)

SiO\(_{2}\)

SiO\(_{x}\)

Low Contrast

Eosam 2024, 9-13 September 2024, Naples, Italy

High vs Low Dielectric Contrast: Reflection Maps for 1DPCs

Dipartimento di Fisica - Università di Pavia

High Contrast

Ta\(_{2}\)O\(_{5}\)

SiO\(_{2}\)

SiO\(_{2}\)

SiO\(_{x}\)

Low Contrast

Eosam 2024, 9-13 September 2024, Naples, Italy

High vs Low Dielectric Contrast: CD Enhancement

Dipartimento di Fisica - Università di Pavia

High Contrast

Ta\(_{2}\)O\(_{5}\)

SiO\(_{2}\)

SiO\(_{2}\)

SiO\(_{x}\)

Low Contrast

Eosam 2024, 9-13 September 2024, Naples, Italy

G. Pellegrini, F. Michelotti, A. Occhicone, M. Celebrano, M. Finazzi, and P. Biagioni

Towards Surface Mode Polarization Control

Dipartimento di Fisica - Università di Pavia

Mogni, Erika, et al. "One‐Dimensional Photonic Crystal for Surface Mode Polarization Control." Advanced Optical Materials (2022): 2200759.

Eosam 2024, 9-13 September 2024, Naples, Italy

Eosam2024 DerivativeFreeOptimalChirality

By Giovanni Pellegrini

Eosam2024 DerivativeFreeOptimalChirality

  • 121