The Development of Broadband Reflective Phase Retarder and Retardance-Free Mirror Sets to Generate and Maintain Circularly Polarized Light at the Target Plane for Multipetawatt Lasers

The advancement of high-power lasers reaching intensities of up to 10²³ W/cm² [1] has unlocked new possibilities in laser–plasma interactions. At these high intensities, the polarization state of the laser plays a crucial role in controlling plasma dynamics and improving ion-acceleration processes [2]. Although conventional wave plates are not suitable for achieving circular polarization at high intensities due to B-integral, there are other ways to control the polarization of the beam through metallic mirrors with dielectric overcoating. Our research focuses on designing broadband all-reflective phase retarders to generate circularly polarized light for the MTW-OPAL Laser System[3] while maintaining its polarization up to the target location. This all-reflective phase retarder can act as the phase retarder when it is out-of-plane configuration while it will act as normal mirrors when it is in-plane configuration. This same mechanism applies to the final focusing optics (off-axis parabolic mirror), which have both in- and out-of-plane configuration due to their physical characteristics. The effect of retardance caused by an OAP to the focal volume of the beam will also be discussed.

[1] J. W. Yoon et al., Optica 8, 630 (2021).

[2] A. Sharma, Sci. Rep. 8, 2191 (2018).

[3] J. Bromage et al., High Power Laser Sci. Eng. 9, e63 (2021).