READ ME File For 'Supporting Data for Doctoral Thesis 'Development of PPLN waveguides for IR upconversion detection and imaging''

Dataset DOI: 10.5258/SOTON/D3567

Date that the file was created: June, 2025

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GENERAL INFORMATION
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ReadMe Author: Noelia Palomar Davidson, University of Southampton [0000-0002-6413-5858]

Date of data collection: 2022-2024

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DATA & FILE OVERVIEW
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This dataset contains:

Figure5.1.xlsx
Total number of 1064nm modes supported in a simulated 5um and 7um wide waveguide, modelled in FIMMWAVE, for a range of refractive index profile parameters 

Figure5.2.xlsx and Figure5.3.xlsx
Effective area values of the 1064nm SHG nonlinear interaction of fundamental modes in a 5um and 7um ridge waveguide

Figure5.4.xlsx
Effective area values of the 1064nm SHG nonlinear interaction of 1064nm fundamental modes with 1st-order vertical 532nm modes in a 5um and 7um ridge waveguide

Figure5.5.xlsx
Overlap integral values for a 1064nm fundamental waveguide mode at a range of parameters in a 7um ridge waveguide, with a 6um MFD Gaussian mode and an 8um MFD Gaussian mode

Figure5.8.xlsx
Calculated average and range for refractive index change and indiffusion depths for a set of Zn deposition powers, thicknesses, and indiffusion temperatures at 532nm

Figure5.9.xlsx
Vertical(Y MFD) and horizontal(X MFD) mode field diameter values measured at 1041nm in waveguides with nominal ridge width 5-7um, and a Zn deposition thickness of 47nm and indiffusion temperature of 900C, alongside model X and Y MFD for the waveguide parameters calculated from Metricon prism coupling measurements.

Figure5.11.xlsx
Experimental phasematching spectra and modelled phasematching spectra of 1064nm SHG in a 7um wide waveguide ridge, with refractive index change 0.0046 and indiffusion depth 4.6um

Figure5.14.xlsx
Experimental phasematching spectra fitted with a sinc^2 curve of 1064nm SHG in a 20mm long and 40mm long waveguide ridge, with fabrication parameters of 47nm Zn deposition thickness and indiffusion temperature of 900C

Figure5.15.xlsx
Experimental phasematching spectra fitted with a sinc^2 curve of 1064nm SHG in waveguide ridges diced with 100um and 300um kerf blades, with fabrication parameters of 40nm Zn deposition thickness and indiffusion temperature of 900C

Figure5.16.xlsx
Waveguide width measured by white light interferometry, smoothed data and polynomial fit. Optical characterisation data and numerical simulated phasematching spectra for waveguide ridges diced with 100um and 300um kerf blades

Figure5.18.xlsx 
Experimental SHG and efficiency data for increasing pump power in a 20mm long 1064nm SHG waveguide, with 7um ridge width, refractive index change 0.0046 and indiffusion depth 4.6um

Figure5.20.xlsx
Experimental phasematching spectra 776nm SHG in a 7um wide waveguide ridge with a 6.1um poling period, for a 10mm and a 20mm long waveguide, with fabrication parameters of 47nm Zn deposition thickness and indiffusion temperature of 900C


Figure5.21.xlsx
Modelled phasematching spectra of 757.3nm SHG in a 7um wide waveguide ridge with a 6.1um poling period, with refractive index change 0.0046 and indiffusion depth 4.6um

Figure5.22.xlsx
Experimental phasematching spectra 757.3nm SHG in a 7um wide waveguide ridge with a 6.1um poling period, for a 20mm long waveguide, with fabrication parameters of 47nm Zn deposition thickness and indiffusion temperature of 900C

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METHODOLOGICAL INFORMATION
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Description of methods used for collection/generation of data: 
Figure5.1.xlsx - LN waveguide model was built in FIMMWAVE, using a finite difference mode solver, using Sellmeier values given by Gayer(https://doi.org/10.1007/s00340-008-2998-2) and a script was used to iterate over refractive index parameters, set to solve for the number of TM modes where imaginary effective index was smaller than 1E-7, with perfectly matched layers of 1um on all borders, and save the complex effective index and MFD values
Figure5.2.xlsx and Figure5.3.xlsx - Modelling software FIMMWAVE was used to save the Ey fundamental (TM00) mode profiles at 1064nm and 532nm for the range of waveguide parameters
Figure5.4.xlsx and Figure5.5.xlsx - Modelling software FIMMWAVE was used to save the Ey fundamental (TM00) mode profiles at 1064nm and the Ey 1st-order vertical (TM01) mode profiles at 532nm for the range of waveguide parameters
Figure5.8.xlsx - Effective index values were measured as described in Chapter 4/README_CH4.txt, using a 532nm source
Figure5.9.xlsx - Waveguide ridge widths were measured using a Leica DM microscope, x100 objective, GX Capture software was used to measure the distance between two parallel lines (waveguide edges) by manually choosing 3 points, this was done at 3 points along the waveguide, on the left-hand side, in the centre and on the right hand side. 1041nm light was butt-coupled from fibre into the TM fundamental waveguide mode, and MFD was measured using the beam profiler described in Chapter 5 of the thesis found at https://eprints.soton.ac.uk/455861/. FIMMWAVE waveguide model parameters were set to refractive index change 0.0044-0.0048 and indiffusion depth 4.4-4.8um, with ridge widths of 5-7um in 0.5um steps, and was set to solve at 1041nm, the complex effective index and MFD values were saved
Figure5.11.xlsx - Experimental data was taken with the setup shown in Figure 5.10 of the thesis, a Thorlabs BP209-VIS beam profiler was used to capture the mode profile images. FIMMWAVE waveguide model parameters were set to refractive index change 0.0046 and indiffusion depth 4.6um, in a 7um ridge width, and a script was used to iterate over temperatures 20-200C for 532nm and 1064nm, set to solve for the first 12 TM modes found by the solver. The complex effective index, MFD values and Ey mode profiles were saved.
Figure5.14.xlsx - Experimental data was taken with the setup shown in Figure 5.10 of the thesis
Figure5.15.xlsx - Experimental data was taken with the setup shown in Figure 5.10 of the thesis
Figure5.16.xlsx - Waveguide width data was taken by Matthew D'Souza, 34mm of a 40mm long waveguide were measured. Experimental data was taken with the setup shown in Figure 5.10 of the thesis. Simulations were generated by numerically solving the three photon ordinary differential equations with a variable propagation constant defined by the polynomial fit to the measured waveguide width
Figure5.18.xlsx - Experimental data was taken with the setup shown in Figure 5.10 of the thesis, for increasing pump powers, where pump power throughput was measured away from the phasematching peak
Figure5.20.xlsx - Experimental data was taken with the setup shown in Figure 5.19 of the thesis, a Thorlabs BP209-VIS beam profiler was used to capture the mode profile images.
Figure5.21.xlsx - FIMMWAVE waveguide model parameters were set to refractive index change 0.0046 and indiffusion depth 4.6um, in a 7um ridge width, and a script was used to iterate over temperatures 120-200C for 378.65nm and 757.3nm, set to solve for the first 12 TM modes found by the solver. The complex effective index, MFD values and Ey mode profiles were saved.
Figure5.22.xlsx - Experimental data was taken with the setup shown in Figure 5.19 of the thesis, a Thorlabs BP209-VIS beam profiler was used to capture the mode profile images.

Methods for processing the data: 
Figure5.1.xlsx - Number of 1064nm modes where the imaginary effective index was smaller than 1E-7 were counted
Figure5.2.xlsx, Figure5.3.xlsx and Figure5.4.xlsx- Equation 2.17 in the thesis was used to calculate the nonlinear overlap integral of the interaction, and then effective area by 1E12/(overlap integral)^2
Figure5.5.xlsx - Overlap integral (Equation 5.1 in thesis) was used to calculate overlap between Ey fundamental (TM00) mode profiles at 1064nm and a Gaussian generated using the fspecial MATLAB function
Figure5.8.xlsx - An average of the effective indices was calculated, and the refractive index change and indiffusion depth values were processed as described in Section 4.1.1 of the thesis
Figure5.9.xlsx - The measured ridge widths were averaged, and their range was used as error. The beam profiler LabView software outputs w0 values for the measured waveguide mode, where MFD=2*w0. The model X and Y MFD values for each ridge width were averaged over the range of refractive index profile parameters the modes were found for.
Figure5.11.xlsx - Experimental data was taken with Dr. Goronwy Tawy, signal power was divided by the transmission listed on the Thorlabs website for the components used (DMLP950,FGB37), conversion is calculated as signal power/pump power and the propagation loss as 10*log(incident pump power/max throughput pump power). Modelled phasematching spectrum; The real component of the effective refractive index at 532nm and 1064nm as a function of temperature was used to calculate the momentum mismatch for a crystal with a 6.7um poling period, the phasematching curve was then found (Equation 2.11 of the thesis), normalised to 1 then multiplied by a factor eta, the waveguide efficiency calculated as Equation 3.1 in the thesis. The Ey mode profiles were used to calculate the nonlinear overlap integral of the different possible interactions.
Figure5.14.xlsx - Signal power was divided by the transmission listed on the Thorlabs website for the components used (DMLP950,FGB37), conversion is calculated as signal power/pump power
Figure5.15.xlsx - Signal and pump powers have to be divided by the transmission listed on the Thorlabs website for the components used (DMLP950,FGB37), and an additional ND filter on the pump beam with 0.3098 transmission, conversion is calculated as signal power/pump power
Figure5.16.xlsx - Outliers of raw waveguide width data were identified as elements more than three scaled median absolute deviations from the median and replaced with the moving median with a 3 point sliding window, the data was then smoothed with a 15 point sliding window moving mean, and fitted with a low-order polynomial. SHG power and numerical data were normalised 
Figure5.18.xlsx - Signal power was divided by the transmission listed on the Thorlabs website for the components used (DMLP950,FGB37), conversion is calculated as signal power/pump power
Figure5.20.xlsx - Experimental data was taken with Dr. Goronwy Tawy. Signal power was divided by the transmission listed on the Thorlabs website for the components used (DMLP505,FGB37), conversion is calculated as signal power/pump power
Figure5.21.xlsx - The real component of the effective refractive index at 378.65nm and 757.3nm as a function of temperature was used to calculate the momentum mismatch for a crystal with a 6.1um poling period, the phasematching curve was then found (Equation 2.11 of the thesis), normalised to 1 then multiplied by a factor eta, the waveguide efficiency calculated as Equation 3.1 in the thesis. The Ey mode profiles were used to calculate the nonlinear overlap integral of the different possible interactions.
Figure5.22.xlsx - Experimental data was taken with Dr. Goronwy Tawy. Signal power was divided by the transmission listed on the Thorlabs website for the components used (DMLP505,FGB37), conversion is calculated as signal power/pump power