README
Data and code package for:

Broadband Achromatic Metalens for the Short-Wave Infrared

This archive contains the data files and code used to generate the figures and analysis presented in the manuscript titled “Broadband Achromatic Metalens for the Short-Wave Infrared”.

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1. TOP-LEVEL STRUCTURE
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The archive is organised into the following folders:

Manuscript Data/
├── Codes/
├── Figure 2/
├── Figure 4/
├── Figure 5/
├── Figure 6/
├── Figure 7/
├── Figure 8/
└── Readme.txt

Each figure folder contains the data files associated with that figure in the manuscript. The Codes folder contains the scripts used to generate analytical targets, process simulation outputs, or prepare the plotted data.

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2. SOFTWARE AND SCRIPT LANGUAGES
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The work was carried out mainly using:

- Lumerical FDTD / Lumerical scripting language
- MATLAB

The code files in the Codes folder are plain-text files, but they correspond to the following scripting environments:

1. MATLAB scripts
- metalens_phase2geometry.txt
- phase_compensation.txt

These files use MATLAB syntax (for example: clear all, load, meshgrid, linspace, zeros, for-loops in MATLAB format).

2. Lumerical script files
- Phase_Conversion_responds.txt
- unitcell_sweep_with_differ_wavelength.txt

These files use the Lumerical scripting language associated with Lumerical FDTD / MODE (for example: getresult, getsweepdata, getdata, matlabsave, integrate, matrix, and Lumerical-style for-loops).

Note:
Although the Lumerical scripts are saved here as .txt files for readability and portability, they are intended to be run inside the Lumerical scripting environment.

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3. FOLDER-BY-FOLDER DESCRIPTION
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Manuscript Data/Codes/
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This folder contains the main scripts used in the workflow.

Files:
- metalens_phase2geometry.txt
  Language: MATLAB
  Purpose:
  Used to generate the target phase-compensation and target group-delay data, and to support mapping from the target phase profile to metalens geometry.

- phase_compensation.txt
  Language: MATLAB
  Purpose:
  Used to compute the phase-compensation curves used in Figure 2.

- Phase_Conversion_responds.txt
  Language: Lumerical script
  Purpose:
  Used to process or generate phase-response and conversion-efficiency data for selected unit-cell geometries used in Figure 5.

- unitcell_sweep_with_differ_wavelength.txt
  Language: Lumerical script
  Purpose:
  Used to sweep the unit-cell structural parameters in FDTD across different wavelengths and generate the phase/transmission data used in Figure 4.

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Manuscript Data/Figure 2/
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This folder contains the calculated phase-compensation profiles used for Figure 2.

Files:
- phi_max.mat
- phi_mid.mat
- phi_min.mat

Description:
These data files contain the phase profiles calculated at the selected design wavelengths. They were obtained using the script:
- Codes/phase_compensation.txt (MATLAB)

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Manuscript Data/Figure 4/
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This folder contains the unit-cell phase-map dataset used for Figure 4.

Files:
- unitcell_PhaseMap_ExEy.mat

Description:
This file contains phase and transmission data obtained by sweeping the unit-cell structural parameters in the Ex and Ey directions using FDTD across different wavelengths. These data were used to produce the phase-response maps shown in the manuscript.

Generated using:
- Codes/unitcell_sweep_with_differ_wavelength.txt (Lumerical script)

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Manuscript Data/Figure 5/
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This folder contains the datasets used for Figure 5, including phase response, conversion efficiency, PB-phase analysis, and target/derived phase and group-delay data.

Files:
- Efficiency_f_L_620_W_150.mat
- Efficiency_f_L_750_W_310.mat
- Parameter_ExEy.mat
- PB_phase_f_L_700_W_130_deg0.mat
- PB_phase_f_L_700_W_130_deg30.mat
- PB_phase_f_L_700_W_130_deg60.mat
- PB_phase_f_L_700_W_130_deg90.mat
- Phase_f_L_620_W_150.mat
- Phase_f_L_750_W_310.mat
- Phi_group_delay.mat
- Phi_phase_compensation.mat
- Target_group_delay.mat
- Target_phase_compensation.mat

Description:
1. Efficiency_f_L_620_W_150.mat and Efficiency_f_L_750_W_310.mat
   Conversion-efficiency data for two representative unit-cell geometries.

2. Phase_f_L_620_W_150.mat and Phase_f_L_750_W_310.mat
   Phase-response data for the same representative geometries.

3. PB_phase_f_L_700_W_130_deg0.mat, PB_phase_f_L_700_W_130_deg30.mat,
   PB_phase_f_L_700_W_130_deg60.mat, and PB_phase_f_L_700_W_130_deg90.mat
   PB-phase response data for different incident polarisation angles.

4. Target_group_delay.mat and Target_phase_compensation.mat
   Target group-delay and phase-compensation data.

5. Phi_group_delay.mat and Phi_phase_compensation.mat
   Processed group-delay and phase-compensation data used in the analysis.

6. Parameter_ExEy.mat
   Parameter-sweep data associated with the Ex/Ey unit-cell geometry space.

Generated or processed using:
- Codes/Phase_Conversion_responds.txt (Lumerical script)
- Codes/metalens_phase2geometry.txt (MATLAB)

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Manuscript Data/Figure 6/
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This folder contains the far-field electric-field distributions used for Figure 6.

Files:
- farfield_E_xz_1.8.mat
- farfield_E_xz_1.9.mat
- farfield_E_xz_2.0.mat
- farfield_E_xz_2.1.mat
- farfield_E_xz_2.2.mat
- farfield_E_xz_2.3.mat

Description:
These files contain the simulated electric-field distributions in the x-z plane at wavelengths from 1.8 µm to 2.3 µm. They were used to generate the wavelength-dependent focusing profiles shown in the manuscript.

Main simulation environment:
- Lumerical FDTD

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Manuscript Data/Figure 7/
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This folder contains the datasets used for Figure 7.

Files:
- allband_trade_off.mat
- farfield_focalE_1.8_200.mat
- focal_efficiency_1.8.mat
- focal_efficiency_1.9.mat
- focal_efficiency_2.0.mat
- focal_efficiency_2.1.mat
- focal_efficiency_2.2.mat
- focal_efficiency_2.3.mat

Description:
1. allband_trade_off.mat
   Data used to plot the all-band trade-off between transmission and polarisation-related performance.

2. farfield_focalE_1.8_200.mat
   Focal-plane field distribution at 1.8 µm, used for focal-plane / PSF-related analysis.

3. focal_efficiency_1.8.mat to focal_efficiency_2.3.mat
   Wavelength-dependent focusing-efficiency data calculated from the far-field results in Figure 6.

Main simulation / processing environments:
- Lumerical FDTD
- MATLAB (for further data processing and plotting where applicable)

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Manuscript Data/Figure 8/
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This folder contains the focal-point polarisation / Stokes-parameter datasets used for Figure 8.

Files:
- stokes_polarisation_focal_1.8.mat
- stokes_polarisation_focal_1.9.mat
- stokes_polarisation_focal_2.0.mat
- stokes_polarisation_focal_2.1.mat
- stokes_polarisation_focal_2.2.mat
- stokes_polarisation_focal_2.3.mat

Description:
These files contain the focal-point polarisation-state information at wavelengths from 1.8 µm to 2.3 µm. They were used to compute and visualise the wavelength-dependent Stokes parameters / polarisation states discussed in the manuscript.

Main processing environment:
- MATLAB

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4. FIGURE-BY-FIGURE SUMMARY
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Figure 2:
- Uses phi_max.mat, phi_mid.mat, and phi_min.mat
- Generated using Codes/phase_compensation.txt (MATLAB)

Figure 4:
- Uses unitcell_PhaseMap_ExEy.mat
- Generated using Codes/unitcell_sweep_with_differ_wavelength.txt (Lumerical script)

Figure 5:
- Uses:
  Efficiency_f_L_620_W_150.mat
  Efficiency_f_L_750_W_310.mat
  Phase_f_L_620_W_150.mat
  Phase_f_L_750_W_310.mat
  PB_phase_f_L_700_W_130_deg0.mat
  PB_phase_f_L_700_W_130_deg30.mat
  PB_phase_f_L_700_W_130_deg60.mat
  PB_phase_f_L_700_W_130_deg90.mat
  Target_group_delay.mat
  Target_phase_compensation.mat
  Phi_group_delay.mat
  Phi_phase_compensation.mat
  Parameter_ExEy.mat
- Generated/processed using Codes/Phase_Conversion_responds.txt (Lumerical script) and Codes/metalens_phase2geometry.txt (MATLAB)

Figure 6:
- Uses farfield_E_xz_1.8.mat to farfield_E_xz_2.3.mat
- Main simulation environment: Lumerical FDTD

Figure 7:
- Uses focal_efficiency_1.8.mat to focal_efficiency_2.3.mat
- Uses allband_trade_off.mat
- Uses farfield_focalE_1.8_200.mat
- Main simulation / processing environments: Lumerical FDTD and MATLAB

Figure 8:
- Uses stokes_polarisation_focal_1.8.mat to stokes_polarisation_focal_2.3.mat
- Main processing environment: MATLAB

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5. FILE FORMATS
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- Most datasets are provided as MATLAB .mat files.
  These can be opened using MATLAB, GNU Octave, or Python (for example via scipy.io.loadmat, depending on MAT-file version).

- The code files are provided as plain-text .txt files.
  Some are MATLAB scripts and some are Lumerical script files, as described above.

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6. NOTES
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- The folders are organised by manuscript figure number for ease of traceability.
- File names have been preserved as used during the analysis workflow.
- Some files are processed datasets rather than raw solver output files.
- The main electromagnetic simulations were performed using Lumerical FDTD.
- Subsequent data processing and plotting were carried out using MATLAB and the scripts provided in the Codes folder.

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7. CONTACT
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For questions about the datasets, code, or file structure, please contact the corresponding author associated with the manuscript.
