Reconstructing intracell polarization with calibrated sapphire-window optics for collimated blue-light generation in a rubidium cell
Abstract
We study the polarization dependence of collimated blue light (CBL) generated near 420~nm by resonant four-wave mixing in thermal rubidium vapor in a sapphire-window cell driven at 780 and 776~nm. Sapphire windows can transform the polarization of pump light before it reaches the vapor, complicating the interpretation of polarization-dependent nonlinear emission. We measured the 780-nm pump Stokes state at an external before-cell reference plane to calibrate the common HWP/QWP preparation optics and recorded 266 off-resonant external output Stokes states after the complete sapphire-window rubidium cell at 90, 100, and 110~∘C in two propagation orientations. Direct paired-wavelength measurements show a mean before-cell 780/776 separation of 4.29∘ and temperature- and orientation-specific complete-cell rotations of 22.20∘--32.02∘, with rms residuals of 4.83∘--12.87∘. Using this calibrated co-prepared pump description, we analyzed 2574 measurements of total spectrally filtered 420-nm CBL intensity. Across the six temperature--orientation data sets, a complete nine-coefficient second-order response yielded cross-validated R2 values of 0.636 to 0.828. These paired-wavelength measurements establish, for each temperature--orientation data set, a fixed relative Stokes-space map between the two co-prepared pump trajectories, with the residual of this mapping defining the experimental uncertainty of the correlated two-pump reduction used in the response model. Thus, the resulting framework combines a reconstructed vapor-entrance polarization coordinate with direct two-wavelength calibration of the assembled cell and provides a practical basis for polarization-controlled nonlinear-optical experiments in sapphire-window vapor cells.
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BibTeX
@misc{ashby2026reconstructing,
title = {{Reconstructing intracell polarization with calibrated sapphire-window optics for collimated blue-light generation in a rubidium cell}},
author = {Sarah Ashby and David Bostanjyan and Mikayel Khanbekyan},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.09441},
eprint = {2611.09441},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.09441},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Reconstructing intracell polarization with calibrated sapphire-window optics for collimated blue-light generation in a rubidium cell
AU - Sarah Ashby
AU - David Bostanjyan
AU - Mikayel Khanbekyan
PY - 2026
DA - 2026/11/06
PB - arXiv
DO - 10.48550/arxiv.2611.09441
UR - https://arxiv.org/abs/2611.09441
AB - We study the polarization dependence of collimated blue light (CBL) generated near 420~nm by resonant four-wave mixing in thermal rubidium vapor in a sapphire-window cell driven at 780 and 776~nm. Sapphire windows can transform the polarization of pump light before it reaches the vapor, complicating the interpretation of polarization-dependent nonlinear emission. We measured the 780-nm pump Stokes state at an external before-cell reference plane to calibrate the common HWP/QWP preparation optics and recorded 266 off-resonant external output Stokes states after the complete sapphire-window rubidium cell at 90, 100, and 110~^∘C in two propagation orientations. Direct paired-wavelength measurements show a mean before-cell 780/776 separation of 4.29^∘ and temperature- and orientation-specific complete-cell rotations of 22.20^∘--32.02^∘, with rms residuals of 4.83^∘--12.87^∘. Using this calibrated co-prepared pump description, we analyzed 2574 measurements of total spectrally filtered 420-nm CBL intensity. Across the six temperature--orientation data sets, a complete nine-coefficient second-order response yielded cross-validated R^2 values of 0.636 to 0.828. These paired-wavelength measurements establish, for each temperature--orientation data set, a fixed relative Stokes-space map between the two co-prepared pump trajectories, with the residual of this mapping defining the experimental uncertainty of the correlated two-pump reduction used in the response model. Thus, the resulting framework combines a reconstructed vapor-entrance polarization coordinate with direct two-wavelength calibration of the assembled cell and provides a practical basis for polarization-controlled nonlinear-optical experiments in sapphire-window vapor cells.
ER -