Polarization-preserving wavefront rotator

Fuente: arXiv
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Main Authors: Karan, Suman, Srivastava, Aman, Todkar, Pratham Sachin, Jha, Anand K.
Format: Preprint
Published: 2026
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_version_ 1866914513870127104
author Karan, Suman
Srivastava, Aman
Todkar, Pratham Sachin
Jha, Anand K.
author_facet Karan, Suman
Srivastava, Aman
Todkar, Pratham Sachin
Jha, Anand K.
contents A K-mirror rotates the wavefront of an incident optical field. However, the rotation always introduces polarization changes in the transmitted field. This is a serious concern for applications ranging from astronomical image derotation to orbital angular momentum spectrum characterization in photonic quantum technology. Recent efforts have shown that the polarization change can be minimized significantly, but these require either a very small base angle that limits the field of view, or mirrors with a customized refractive index. Making the transmitted polarization state completely independent of the rotation angle has remained an open problem. In this work, we show that placing half-wave plates before and after a K-mirror and rotating them synchronously at half the K-mirror rotation angle makes the polarization change in the transmitted field exactly independent of the rotation angle. This works for any wavefront rotator, any base angle, any mirror refractive index, and any input state of polarization. We experimentally demonstrate the approach using a K-mirror with a base angle of $30^{\circ}$, which gives the largest field of view among practical designs, and find a mean polarization error of ~1%, limited only by the retardance imperfection of commercially available half-wave plates. This has significant practical implications for applications that require precise wavefront rotation without polarization change.
format Preprint
id arxiv_https___arxiv_org_abs_2604_25475
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Polarization-preserving wavefront rotator
Karan, Suman
Srivastava, Aman
Todkar, Pratham Sachin
Jha, Anand K.
Optics
Instrumentation and Methods for Astrophysics
Quantum Physics
A K-mirror rotates the wavefront of an incident optical field. However, the rotation always introduces polarization changes in the transmitted field. This is a serious concern for applications ranging from astronomical image derotation to orbital angular momentum spectrum characterization in photonic quantum technology. Recent efforts have shown that the polarization change can be minimized significantly, but these require either a very small base angle that limits the field of view, or mirrors with a customized refractive index. Making the transmitted polarization state completely independent of the rotation angle has remained an open problem. In this work, we show that placing half-wave plates before and after a K-mirror and rotating them synchronously at half the K-mirror rotation angle makes the polarization change in the transmitted field exactly independent of the rotation angle. This works for any wavefront rotator, any base angle, any mirror refractive index, and any input state of polarization. We experimentally demonstrate the approach using a K-mirror with a base angle of $30^{\circ}$, which gives the largest field of view among practical designs, and find a mean polarization error of ~1%, limited only by the retardance imperfection of commercially available half-wave plates. This has significant practical implications for applications that require precise wavefront rotation without polarization change.
title Polarization-preserving wavefront rotator
topic Optics
Instrumentation and Methods for Astrophysics
Quantum Physics
url https://arxiv.org/abs/2604.25475