This project provides tools for simulating the optical and plasmonic properties of nanoshell structures, particularly in the quasi-static regime, both below and above the emission threshold. The core theory behind this project has been published in the open-access paper:
Reference: "Emission and lasing properties of a single nanoshell spaser nanoparticle", Nanophotonics (2024).
This repository contains:
- Source codes for simulating nanoshells with gain-enhanced cores.
- Headers defining material models and key functions.
- Tools for calculating steady-state polarizabilities and time-dependent dynamics.
- Example input files and testing scripts.
The code uses the GNU Scientific Library (GSL) and Armadillo for numerical computations.
To compile the project, ensure the following dependencies are installed:
- A C++ compiler (e.g., g++)
- GNU Scientific Library (GSL)
- Armadillo C++ library
-
Run the
configurescript to check dependencies:./configure
-
Compile the project using the Makefile:
make
-
To clean compiled binaries:
make clean
This file describes the nanoshell structure parameters:
| Parameter | Description | Example Value |
|---|---|---|
| External radius (nm) | Radius of the nanoshell, (a) in the paper | 10 |
| Emission width (eV) | (\hbar \Delta), amplitude of the emission permittivity of the gain medium | 0.15 |
| Emission frequency (eV) | (\hbar \omega_g), emission frequency of the gain medium | 2.8122 |
| Gain level | (-G), negative gain level (future versions may switch to (G)) | -0.033 |
| Spectrum bounds (eV) | (\omega_{min}), (\omega_{max}), bounds of the spectral range of interest | 2.0, 4.5 |
| Metal type | Material of the shell (e.g., silver) |
silver |
| Metal model | Model for the metal (drude, spline) |
drude |
| Gain medium model | Model for the active core medium (lorentz, flat) |
lorentz |
| Host material | Surrounding medium (e.g., water) |
water |
| Excitation field amplitude | (E_0), excitation field (arbitrary units); compare with saturation field amplitude (E_{sat}) (see Esat.cxx in src) | 1.e-30 |
| Radius ratio | (\rho), ratio of inner to outer radius | 0.6 |
| Core material | Material of the nanoshell core (e.g., silica) |
silica |
This file specifies time-dependent simulation parameters:
| Parameter | Description | Example Value |
|---|---|---|
| Total time (ps) | Duration of the simulation. | 100 |
| Pump-on time (ps) | Time at which the pump is switched on (in ns). | 10 |
To include and use the functions defined in cup.H, you must include the following headers in your code in the specified order:
#include "../src/headers/math33.H"
#include "../src/headers/nanoshell.H"
#include "../src/headers/cup.H"Before using subroutines in cup.H, you must:
- Define a
nanosphereinstance (e.g.,nanosphere ns). - Initialize it using:
ns.init();
- Set the metal and active medium using:
ns.set_metal("<metal type>", "<model>", 1); ns.set_active("<gain medium model>");
The tests directory includes sample programs demonstrating the functionality of the Nano-Shell Simulation Project. These programs can be compiled and executed to verify specific features of the code. Below is an overview of the included test programs:
- time_behavior.cxx: Simulates the time-dependent behavior of the complex dipole moment for a given frequency.
- threshold.cxx: Calculates the threshold gain ( G_{\text{th}} ) and the threshold frequency ( \omega_{\text{th}} ), as defined in the associated publication.
- steady_state.cxx: Computes the steady-state spectrum of the polarizability.
To compile and run the test programs, navigate to the tests directory and use the following commands:
g++ -Wall -I../src/headers -L../src/lib time_behavior.cxx -o time_behavior -lgsl -lgslcblas -lm -larmadillo
./time_behavior
g++ -Wall -I../src/headers -L../src/lib threshold.cxx -o threshold -lgsl -lgslcblas -lm -larmadillo
./threshold
g++ -Wall -I../src/headers -L../src/lib steady_state.cxx -o steady_state -lgsl -lgslcblas -lm -larmadillo
./steady_stateThis project is released under the GNU GENERAL PUBLIC LICENSE. See LICENSE for details.
Contributions are welcome! If you find any bugs or have feature requests, feel free to open an issue or submit a pull request.
For questions or collaboration opportunities, please reach out to Alessandro Veltri at alessandro.veltri@gmail.com.