DOI: 10.17035/d.2022.0138005445
title: Gain measurements on VCSEL material using segmented contact technique - data

description: This dataset is organised into 7 folders: FIG2_TopMirrorReflectivity - Contains two datafiles which contain the simulated top mirror reflectivities for different cap thicknesses. "AirTopMirrorReflectivity" is with air above the cap layer, and "CrAuTopMirrorReflectivity" with a 10nm Chromium layer and a 300nm Gold layer above the cap. Column 1 gives the Cap Thickness (nm), Column 2 the Cavity Resonance Wavelength (nm), Column 3 the Top Mirror Reflectivity at the cavity resonance wavelength (dimensionless). FIG3_SegmentedContactPI - Contains four datafiles with the power-current characteristics of two different segmented contact sections, one with a nominally 62nm cap thickness, and the other with a nominally 124nm cap thickness. For each device, section 2 was pumped and the light emission in the in-plane and vertical direction was measured. Column 1 gives the raw current output (mA) of the pulsed current source, column 2 the current density (kA/cm^2) after correcting for leakage currents and current spreading, column 3 gives the average optical power output (uW). The current density values in column 2 are only valid above 0.1kA/cm^2, where the diode I-V curve is close to linear. FIG4_GainResults - Contains the measured gain spectra for a range of temperatures and current densities, the in-plane mode loss values, and the raw amplified spontaneous emission (ASE) data used to obtain the gain spectra. This folder contains 3 sub-folders that correspond to each run, as the gain measurement for carried out 3 times, and a datafile called "InplaneInternalModeLoss_Summary" with the measured in-plane mode loss. In each run sub-folder, for each temperature, there is a datafile ("Run#_#degC_GainSummary") that contains the gain spectra and a folder that contains the raw ASE datafiles ("#_#_S#S#_#mA_#mA"). The ASE datafile filename gives the temperature (Celsius), current density (kA/cm^2), the sections that are pumped, and the current (mA) suppled by each current source. Note that the letter d is used instead of a decimal point. - For "InplaneInternalModeLoss_Summary", column 1 gives the temperature, column 2-4 gives the mode loss (cm^-1) for each run. The mode loss values were obtained by averaging over a 5nm wavelength range for each current density and then taking the mean of those values. Column 5 gives the mean (cm*-1) of columns 2-4, and column 6 gives the standard error. - For "Run#_#degC_GainSummary", column 1 gives the wavelength (nm) and columns 2-8 gives the gain spectra (cm^-1) for each current density. - For "#_#_S#S#_#mA_#mA", column 1 gives the wavelength (nm) and column 2 gives the ASE intensity (counts). Below this contains the spectrometer settings that were used. FIG5_SPVS -Contains 6 datafiles in total. There are 5 datafiles with a filename format "SPVS#", where the # is replaced by the temperature in Celsius, that contain the photovoltage response. The datafile "SPVS_PeakWavelengthSummary" contains the cavity resonance wavelength, determined from the photovoltage peak, at each temperature. - For the files "SPVS#", column 1 gives the wavelength (angstroms) of the light incident on the sample, column 2 gives the photovoltage response (V), and column 3 gives the standard error (V) of the photovoltage. - For the file "SPVS_PeakWavelengthSummary", column 1 gives the temperature (Celsius), column 2 gives photovoltage peak wavelength (nm). FIG6_PI - Contains the measured threshold current density, and the Power-Current (P-I) curves of VCSEL devices used to determine the threshold current. There are 5 folders containing raw Power-Current curves of devices, where the folder name gives the temperature (Celsius) at which measurements were taken. The filename of the P-I datafiles give the mesa diameter (um), pulsewidth (us), and temperature (Celsius). There are 3 datafiles called "DeviceOxideSize" which contain device geometry information, "ThresholdCurrentSummary" which contains a summary of the threshold currents obtained from the peak in the 2nd derivative of the P-I curves after smoothing using an n-point linear fit, and "ThresholdCurrentDensitySummary" which contains a summary of the measured threshold current density of each device at each temperature. - For the P-I datafiles, P-I data starts from row 20 with measurement parameters given in previous rows. Column 1 gives the injection current (mA), and column 2 gives the average power (W). - For "DeviceOxideSize", column 1 gives the mesa diameter (um), column 2 gives the nominal oxide aperture diameter (um), column 3 gives the area for a circular oxide aperture (um^2), and column 4 gives the corrected area (um^2), due to a slightly non-circular oxide aperture, which was used to convert the threshold currents into threshold current densities.. - For "ThresholdCurrentSummary", column 1 gives the temperature (Celsius), columns 2-5 gives the threshold current (mA) with the mesa diameter (um) of the device it corresponds to given in the headers in row 1. - For "ThresholdCurrentDensitySummary", column 1 gives the temperature (Celsius), columns 2-5 gives the threshold current density (mA) with the mesa diameter (um) of the device it corresponds to given in the headers in row 1, column 6 gives the mean threshold current density (kA/cm^2), column 7 gives the standard error (kA/cm^2). FIG7_ThresholdGain - Contains 4 folders called "2ParameterGainFit" which gives the in-plane modal gain-current density fits at the resonance wavelength, "MaterialGain" which gives the threshold material gain values determined from experimental measurements, "SimulationFits" which gives the in-plane optical mode parameters determined through simulation that was used to convert the in-plane gain into the material gain, and "ThresholdGainSimulation" which gives the simulated threshold material gain for different internal optical loss values. -Within "2ParameterGainFit" are 3 datafiles which correspond to the 3 gain measurement runs. A function of the form g = g_0*LN(J/J_tr) was fitted to the experimental in-plane net modal gain values at the cavity resonance wavelength (obtained from SPVS). g is the in-plane net modal gain, and J is the current density. g_0 and J_tr are fit parameters. Column 1 gives the temperature (Celsius), column 2 gives the fitted g_0 (/cm), and column 3 gives the fitted J_tr (kA/cm^2). -Within "MaterialGain" are 2 datafiles called "ExperimentalMaterialGain" which contain the threshold gain values and "ExperimentalMaterialGainError" which contain the associated errors. For "ExperimentalMaterialGain", column 1 gives the temperature (Celsius), column 2-4 gives the in-plane net modal gain (/cm) at threshold current density for each run, determined from the fit parameters in "2ParameterGainFit", column 5 gives the mean in-plane modal gain value, column 6 gives the in-plane modal gain (/cm) after adding the internal mode loss values from "InplaneInternalModeLoss_Summary", column 7 gives the material gain (/cm) that was after multiplying the in-plane modal gain value with the in-plane material gain conversion factor in "SimulationFits". For "ExperimentalMaterialGainError", column 1 gives the temperature (Celsius), column 2 gives the standard error (/cm) of the mean threshold net modal gain (/cm), column 3 gives the threshold net modal gain error contribution (/cm) due to the error in the measured threshold current density, column 4 gives the threshold net modal gain error contribution (/cm) due to the error in the measured cavity resonance wavelength, column 5 gives the combined threshold net modal gain error (/cm), column 6 gives the threshold material gain error (/cm) by multiplying the column 5 values with the conversion factor. -Within "SimulationFits" are 4 datafiles called "confinement_factor" which gives the confinement factor (dimensionless) of the simulated in-plane TE mode, "group_velocity" which gives the the group velocity (m/s) of the simulated in-plane TE mode, "normalised_effective_index" which gives the effective index divided by the refractive index (dimensionless) of the quantum well material, and "InPlaneModalGainToMaterialGain" which gives the conversion factor (dimensionless) used to convert the in-plane modal gain into the material gain of the vertical mode. Quadratic functions of the form, a*lambda^2 + b*lambda + c, where lambda is the optical wavelength (nm) and a,b,c are the coefficients, were fitted to simulation results over the wavelength range 880-920nm. Column 1 gives the temperature (Celsius), column 2 gives a, column 3 gives b, column 4 gives c. -Within "ThresholdGainSimulation" are 3 datafiles which give the threshold material gain values calculated from simulated mirror reflectivities. The internal optical mode loss value (/cm) used is given in the filename. Column 1 gives the temperature, column 2 gives the cavity resonance wavelength (nm), column 3 gives the gain enhancement factor due to standing wave effects (dimensionless), column 4 gives the top mirror reflectivity (dimensionless), column 5 gives the bottom mirror reflectivity (dimensionless), and column 6 gives the threshold material gain (/cm). FIG8_GainPeak -Contains the measured peak gain values and gain-peak wavelengths which were determined by fitting 3rd order polynominals to the gain spectra around the gain peak. There are 5 datafiles with the temperature (Celsius) given in the filename. Column 1 gives the current density (/cm), columns 2-4 gives the measured gain-peak wavelengths (nm) for each run, column 5-7 gives the measured peak net modal gain values (/cm), column 8 gives the mean gain-peak wavelength (nm), column 9 gives the mean peak net modal gain value (/cm), column 10 gives the peak material gain (/cm), column 11 gives the standard error in the mean gain-peak wavelength (nm), column 12 gives the standard error in the mean peak net modal gain (/cm), column 13 gives the standard error in the mean peak material gain (/cm).