We demonstrate a Mueller polarimeter in which the polarization-state generator and analyzer are both composed of a linear polarizer and two liquid-crystal variable retarders. The polarimeter is designed to optimize the accuracy of the final results by minimization of the condition numbers of the modulation and analysis matrices. The polarimeter calibration, a difficult task by conventional procedures, is achieved easily by use of the eigenvalue method of Compain et al. [Appl. Opt. 38, 3490 (1999)]. The overall polarimeter performance is tested with a linear polarizer at various angles and a compensator at various retardations.
This article provides a brief overview of both established and novel ellipsometry techniques, as well as their applications. Ellipsometry is an indirect optical technique, in that information about the physical properties of a sample is obtained through modeling analysis. Standard ellipsometry is typically used to characterize optically isotropic bulk and/or layered materials. More advanced techniques such as Mueller ellipsometry, also known as polarimetry in the literature, are necessary for the complete and accurate characterization of anisotropic and/or depolarizing samples that occur in many instances, both in research and in real-life activities. In this article, we cover three main subject areas: Basic theory of polarization, standard ellipsometry, and Mueller ellipsometry. The first section is devoted to a short, pedagogical introduction of the formalisms used to describe light polarization. The second section is devoted to standard ellipsometry. The focus is on the experimental aspects, including both pros and cons of commercially available instruments. The third section is devoted to recent advances in Mueller ellipsometry. Application examples are provided in the second and third sections to illustrate how each technique works.
Compact sources in the mid-wave infrared (MWIR) are needed for applications ranging from spectroscopy to free-space communication. Ultrathin incandescent metasurfaces are promising candidates, offering the possibility to tune the emission spectrum, directivity, and modulation speed. However, control over polarization remains a challenge, especially when it comes to the emission of circularly polarized light. Here, we report the emission of polarized MWIR radiation from a 700 nm thick incandescent chiral metasurface. The degree of polarization is above 0.5 with degree of circular polarization of 0.38 at 5 µm. The metasurface is heated by the Joule effect, and the emission can be modulated beyond 10 MHz. This could enable detection techniques that use polarization as an additional degree of freedom.
We propose a photovoltaic solar cell design based on a 100 nm thick absorbing layer made of hydrogenated amorphous silicon and patterned as a two-dimensional planar photonic crystal (PPC). After scanning the parameters of the PPC within the patterned cell, optical simulations performed on the best configuration obtained reveal that a relative increase in the integrated absorption inside the active layer of 28% can be expected between 300 and 720 nm compared to an equivalent but nonpatterned cell under normal incidence. Besides, this integrated absorption is found to be robust toward the angle of incidence. Incident light is efficiently coupled to leaky mode resonances of the PPC provided an appropriated tuning of its parameters. The effects of the reflectance of the back contact coupled to a conductive optical spacer on the absorption are also discussed.