Abstract
Advances in vectorial polarisation-resolved imaging are bringing new capabilities to applications ranging from fundamental physics through to clinical diagnosis. Imaging polarimetry requires determination of the Mueller matrix (MM) at every point, providing a complete description of an object's vectorial properties. Despite forming a comprehensive representation, the MM does not usually provide easily-interpretable information about the object's internal structure. Certain simpler vectorial metrics are derived from subsets of the MM elements. These metrics permit extraction of signatures that provide direct indicators of hidden optical properties of complex systems, while featuring an intriguing asymmetry about what information can or cannot be inferred via these metrics. We harness such characteristics to reveal the spin-Hall effect of light, infer microscopic structure within laser-written photonic waveguides, and conduct rapid pathological diagnosis through analysis of healthy and cancerous tissue. This provides new insight for the broader usage of such asymmetric inferred vectorial information.
Highlights
It explains the scope of interpretation of the Δ and allows further applications. Using this newly unified representation, we emphasize illustration of the derived vectorial metrics through Mueller matrix (MM) measurements of various objects—objective lenses, photonic waveguides, and biological tissue. Through analysis of such metrics, we reveal the appearance of circular retardance (M1); the combination of linear diattenuation (LD) and linear polarizance (M2), multilayered linear retardance (LR) (M3); and the sequence of a linear diattenuator and a linear retarder (M4)
The observation of trends in the vectorial metric values and their analysis give us a better insight into the vectorial properties of the photonic waveguides, including a better understanding of the loss and polarization effects as well as providing guidance for further customized fabrication. It reveals that (1) different types of complex layered polarization structures exist inside the waveguides; as Metric 2 (M2) can be interpreted as indicating an anisotropic absorption layer before a depolarization layer, Metric 3 (M3) can be used to characterize the contributions from stress birefringence induced, form birefringence induced, as well as scattering induced retardance; (2) M2 decreased with increasing pulse energy, whereas the scattering induced depolarization increased
We took advantage of the vectorial metrics derived from the MM—that can provide a simple representation of complex vectorial phenomena—to demonstrate the spin Hall effect of light (SHEL), to analyze the vectorial characteristics of laser written waveguides, and to facilitate the discrimination between healthy and cancerous tissue
Summary
Light and the optical properties of matter have long been harnessed across different areas of research and applications.[1]. As it constrains the physical information that the metrics could extract from objects, such as how multiple layers are constituted [see Fig. 1(c), Supplementary Material 2] It explains the scope of interpretation of the Δ and allows further applications. Using this newly unified representation, we emphasize illustration of the derived vectorial metrics through MM measurements of various objects—objective lenses, photonic waveguides, and biological tissue. New metrics could be developed that enable extraction of more useful physical information about the target and benefit more applications, whereas the asymmetric inference behind the metrics can be explored again (see Sec. 5). Future impact of these developments could range from quantum physics to clinical diagnosis
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