Design of a frequency-independent optic axis Pancharatnam-based achromatic half-wave plate

Kavli Affiliate: Nobuhiko Katayama

| First 5 Authors: [#item_custom_name[1]], [#item_custom_name[2]], [#item_custom_name[3]], [#item_custom_name[4]], [#item_custom_name[5]]

| Summary:

Pancharatnam-based achromatic half-wave plates (AHWP) achieve high
polarization efficiency over a broad waveband. These AWHPs generally contain a
property whereby the optic axis is dependent on the electromagnetic frequency
of the incident radiation. When the AHWP is used to measure incident polarized
radiation with a finite detection bandwidth, this frequency dependence causes
an uncertainty in the determination of the polarization angle due to the
limited knowledge of the shape of the source spectrum and detection band. To
mitigate this problem, we propose new designs of the AHWP which eliminate the
frequency dependence of the optic axis over the bandwidth whilst maintaining
high modulation efficiency. We carried out this optimization by tuning the
relative angles among the individual half-wave plates of the five and nine
layer AHWPs. The optimized set of relative angles achieves a
frequency-independent optic axis over the fractional bandwidth, a bandwidth
over which polarization efficiency is greater than 0.9, of 1.3 and 1.5 for the
five and nine layer AHWPs, respectively. We also study the susceptibility of
the alignment accuracy on the polarization efficiency and the frequency
dependence of the optic axis, which provides a design guidance for each

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