Design and fabrication all-dielectric broadband reflection phase shifting mirror at near-infrared wavelengths for high intensity lasers

Abstract

In this paper, we designed the broadband all-dielectric reflection phase shifting mirror to convert the linear polarization incident light to circularly polarization reflected light in the design wavelength range (750nm~850nm) for ultra-high intensity laser application. The 48 multilayer coated mirror used Ta2O5 and SiO2 as high and low refractive index materials. The theoretical design results indicated that at the incident angle 45 degree, the reflectivity of s- polarization light exceeded 99.9% and p- polarization light exceeded 99.5%, and phase shift values between s- and p- polarization lights were -90±5 degrees in the design wavelength range. The all-dielectric broadband reflection phase shifting mirror was fabricated with an ion beam sputtering system. The measurement results indicated that the reflectivity of s-polarization light exceeded 99.9% and p- polarization light exceeded 99.3%, and phase shift values between s- and p-polarization lights were -95~-77 degrees. The reflectivity of s- polarization light and p- polarization light conform well to theoretical design values. However, the phase shift values slightly deviated from theoretical design results in part of the wavelength range. With features of high reflectivity and invertible linear to circular polarization conversion, the all-dielectric broadband reflection phase shifting mirror can be a good replacement for quarter wave plate in high intensity laser region, and offers a further step in developing polarization and phase manipulation devices.