Proper characterization of molecular chiroptical properties is vital for organic chemistry and drug development. Nonetheless, narrow spectral ranges and the necessity for specialized equipment often limit traditional methods such as optical rotatory dispersion and electronic circular dichroism. Here, we introduce Mueller matrix polarimetry (MMP) as a more versatile tool for chiroptical analysis, capable of simultaneously capturing circular dichroism and optical rotatory dispersion spectra across ultraviolet to near-infrared wavelengths in a single measurement. We applied MMP to chiral metal complexes of Al, Mn, and Co, commonly used as catalysts in asymmetric syntheses. Using a robust experimental methodology, MMP distinguished enantiomeric forms and provided reliable chiroptical information by leveraging the inherent relationship between circular dichroism and optical rotatory dispersion. We interpreted our findings on the basis of density functional theory simulations, compared them to traditional electronic circular dichroism and absorption spectroscopies, and performed the Kramers-Kronig analysis. The combined approach of chiroptical MMP and ab-initio, for example, reveals delicate near-infrared chiroptical spectra of a neutral cobalt metal complex. Although MMP is more commonly used for solid state, the developed experimental protocol significantly expands its capabilities to solutions. It allows measurements without the need for both enantiomers and offers new insights into molecular chirality with potential applications across traditional and interdisciplinary branches of science and industry.

Optically pumped spintronic terahertz emitters (STEs) have, in less than a decade, strongly impacted terahertz (THz) source technology, by the combination of their Fourier‐limited ultrafast response, their phononless emission spectrum and their wavelength‐independent operation. However, the intrinsic strength of the inverse spin Hall effect governing these devices introduces a challenge: the optical‐to‐terahertz conversion efficiency is considerably lower than traditional sources. It is therefore primordial to maximize at least their electromagnetic efficiency independently of the spin dynamics at play. Using a rigorous time‐domain treatment of the electromagnetic generation and extraction processes, an optimized design is presented and experimentally confirmed. With respect to the strongest reported spintronic THz emitters it achieves a 250% enhancement of the emitted THz field and therefore an 8 dB increase of emitted power. This experimental achievement brings STE close to the symbolic barrier of mW levels. The design strategy is generically applicable to any kind of ultrafast spin‐to‐charge conversion (S2C) system. On a broader level, our work highlights how a rigorous handling of the purely electromagnetic aspects of THz spintronic devices can uncover overlooked aspects of their operation and lead to substantial improvements.

Optical metasurface technology promises an important potential for replacing bulky traditional optical components, in addition to enabling new compact and lightweight metasurface-based devices. Since even subtle imperfections in metasurface design or manufacture strongly affect their performance, there is an urgent need to develop proper and accurate protocols for their characterization, allowing for efficient control of the fabrication. We present non-destructive spectroscopic Mueller matrix ellipsometry in an uncommon off-specular configuration as a powerful tool for the characterization of orthogonal polarization beam-splitters based on a-Si:H nanopillars. Through Mueller matrix analysis, the spectroscopic polarimetric performance of the ±1 diffraction orders is experimentally demonstrated. This reveals a wavelength shift in the maximum efficiency caused by fabrication-induced conical pillars while still maintaining a polarimetric response close to ideal non-depolarizing Mueller matrices. We highlight the advantage of the spectroscopic Mueller matrix approach, which not only allows for monitoring and control of the fabrication process itself, but also verifies the initial design and produces feedback into the computational design.

Unlike traditional group-6 transition metal dichalcogenides (TMDs), group-10 TMDs such as PtSe2 and PdTe2 possess highly tuneable indirect bandgaps, transitioning from semiconducting in the near-infrared to semimetal behavior with a number of monolayers (MLs). This opens up the possibility of TMD-based mid-infrared and terahertz optoelectronics. Despite this large potential, the optical properties of such materials have shown an extremely large disparity between that predicted and measured. For example, simulations show that a few MLs is required for the semiconductor-semimetal transition, whilst tens of MLs is found experimentally. This is a result of widely used optical extrapolation methods to determine bandgaps, such as the Tauc plot approach, that are not adapted here owing to i) nearby direct transitions, ii) the material dimensionality and iii) large changes in the non-parabolic bandstructure with MLs. Here, uniquely combining optical ellipsometry to determine the complex permittivity, terahertz time resolved spectroscopy for the complex conductivity and in-depth density functional theory (DFT) simulations, it is shown that the optical properties and bandstructure can be determined reliably and demonstrate clearly that the semiconductor-semimetal transition occurs for PtSe2 layers approximate to 5 MLs. The microscopic origins of the observed transitions and the crucial role of the Coulomb interaction for thin semiconducting layers, and that of interlayer van der Waals forces for multilayer semimetallic samples are also demonstrated. This work of combining complimentary experimental techniques and extensive simulations avoids the application of constrained extrapolation methods to determine the optical properties of group-10 TMDs, and will be of importance for future mid-infrared and terahertz applications.

The boom in terahertz technologies of the last few decades is now not limited to the use of electric charge, but also fully exploits spin. Revolutionary spintronic terahertz emitters (STEs) offer versatile usage under a wide range of visible and infrared excitation wavelengths, arbitrary reflection/transmission excitation geometries, and utilization with most femtosecond oscillators and amplifiers. STE emission results in a 30THz-broad and gapless spectrum with easily controllable polarization. However, the optical-to-terahertz conversion efficiency is lower than traditional THz sources. Here, we demonstrate experimentally the enhancement of factor 6 in STEs power, which is the highest improvement nowadays. We integrate STEs with our optimized photonic cavities and provide procedures on how to dramatically increase efficiency.

As a two-dimensional (2D) material for terahertz (THz) applications, platinum diselenide (PtSe 2 ) can be uniquely tuned from a semiconductor in the near infrared to a semimetal with the number of atomic layers, in contrast to other transition metal dichalcogenides (TMDs). Consequently, the material has unique photonic properties at THz frequencies that can be enhanced by atomic layer engineering. Here, we demonstrate that a controlled THz nonlinearity - tuned from monolayer to bulk PtSe 2 - can be realized in wafer size PtSe 2 through the generation of ultrafast photocurrents and the engineering of the bandstructure valleys. Further, we show layer dependent circular dichroism, where the sign of the ultrafast currents and hence the phase of the emitted THz pulse can be controlled through the excitation of different bandstructure valleys. In particular, we show that a semimetal has a strong dichroism that is absent in the monolayer and few layer semiconducting limit. The microscopic origins of this TMD bandstructure engineering is highlighted through detailed DFT simulations, and shows the circular dichroism can be controlled when PtSe 2 becomes a semimetal and when the K-valleys can be excited. As well as showing that PtSe 2 is a promising material for THz generation through layer controlled optical nonlinearities, this work opens up new class of circular dichroism materials beyond the monolayer limit that has been the case of traditional TMDs, and impacting a range of domains from THz valleytronics to harmonic generation.

Optical metasurface technology promises an important potential for replacing bulky traditional optical components, in addition to enabling new compact and lightweight metasurface-based devices. Since even subtle imperfections in metasurface design or manufacture strongly affect their performance, there is an urgent need to develop proper and accurate protocols for their characterization, allowing for efficient control of the fabrication. We present non-destructive spectroscopic Mueller matrix ellipsometry in an uncommon off-specular configuration as a powerful tool for the characterization of orthogonal polarization beam-splitters based on a-Si:H nanopillars. Through Mueller matrix analysis, the spectroscopic polarimetric performance of the ±1 diffraction orders is experimentally demonstrated. This reveals a wavelength shift in the maximum efficiency caused by fabrication-induced conical pillars while still maintaining a polarimetric response close to ideal non-depolarizing Mueller matrices. We highlight the advantage of the spectroscopic Mueller matrix approach, which not only allows for monitoring and control of the fabrication process itself, but also verifies the initial design and produces feedback into the computational design.

Spectroscopic Mueller matrix ellipsometry is becoming increasingly routine across physical branches of science, even outside optics. The highly sensitive tracking of the polarization-related physical properties offers a reliable and non-destructive analysis of virtually any sample at hand. If coupled with a physical model, it is impeccable in performance and irreplaceable in versatility. Nonetheless, this method is rarely adopted interdisciplinarily, and when it is, it often plays a supporting role, which does not take benefit of its full potential. To bridge this gap, we present Mueller matrix ellipsometry in the context of chiroptical spectroscopy. In this work, we utilize a commercial broadband Mueller ellipsometer to analyze the optical activity of a saccharides solution. We verify the correctness of the method in the first place by studying the well-known rotatory power of glucose, fructose, and sucrose. By employing a physically meaningful dispersion model, we obtain 2π-unwrapped absolute specific rotations. Besides that, we demonstrate the capability of tracing the glucose mutarotation kinetics from just one set of measurements. Coupling the Mueller matrix ellipsometry with the proposed dispersion model ultimately leads to the precisely determined mutarotation rate constants and spectrally and temporally resolved gyration tensor of individual glucose anomers. In this view, Mueller matrix ellipsometry may stand as an offbeat yet equal technique to those considered classical chiroptical spectroscopy techniques, which may help open new opportunities for broader polarimetric applications in biomedicine and chemistry.

Platinum diselenide (PtSe2) is a promising two-dimensional (2D) material for the terahertz (THz) range as, unlike other transition metal dichalcogenides (TMDs), its bandgap can be uniquely tuned from a semiconductor in the near infrared to a semimetal with the number of atomic layers. This gives the material unique THz photonic properties that can be layer-engineered. Here, we demonstrate that a controlled THz nonlinearity-tuned from monolayer to bulk PtSe2-can be realized in wafer size polycrystalline PtSe2 through the generation of ultrafast photocurrents and the engineering of the bandstructure valleys. This is combined with the PtSe2 layer interaction with the substrate for a broken material centrosymmetry, permitting a second order nonlinearity. Further, we show layer dependent circular dichroism, where the sign of the ultrafast currents and hence the phase of the emitted THz pulse can be controlled through the excitation of different bandstructure valleys. In particular, we show that a semimetal has a strong dichroism that is absent in the mono layer and few layer semiconducting limit. The microscopic origins of this TMDb and structure engineering are highlighted through detailed DFT simulations, and shows the circular dichroism can be controlled when PtSe2 becomes a semimetal and when the K-valleys can be excited. As well as showing that PtSe2 is a promising material for THz generation through layer controlled optical nonlinearities, this work opens up a new class of circular dichroism materials beyond the monolayer limit that has been the case of traditional TMDs, and impacting a range of domains from THz valleytronics, THz spintronics to harmonic generation.

Chirality – the non-superimposability of an object on its mirror image – shows its twists at all scales, from giant stellar galaxies to the electronic structure of materials. It enters into nearly every aspect of everyone’s daily routine without acknowledging it. Yet, it governs the stereochemistry of all molecular processes in nature, making them life-forming or life-incompatible. It makes the knowledge of molecular spatial configuration essential in pharmacy, medicine, and biochemistry. Here, by combining spectroscopic Mueller matrix ellipsometry and suitable theory, we experimentally demonstrate and theoretically verify the advantage of the proposed method to determine dispersion characteristics of molecular chirality. We first show how the Mueller matrix relates to both macroscopic and microscopic physical quantities used commonly in description of molecular chirality. Next, we experimentally determine quantitative observables such as specific rotation (with sensitivity 0.001 rad) of limonene enantiomers. We believe that our findings may provide a deeper insight into the problematics and potentially extend the scope of the state-of-the-art Mueller matrix ellipsometry beyond the classical optics and photonics.

Mueller matrix ellipsometry has been used to precisely characterize quartz waveplates for demanding applications in the semiconductor industry and high precision polarimetry. We have found this experimental technique to be beneficial to use because it enables us to obtain absolute and precise measurement of retardation in a wide spectral range, waveplate orientation, and compound waveplate adjustment. In this paper, the necessity of including the optical activity in the Mueller matrix model and data treatment is demonstrated. Particularly, the optical activity of the quartz influences the adjustment of misalignment between the perpendicularly oriented waveplates of the compound biplate. We demonstrate that omitting the optical activity from the model leads to inaccurate values of the misalignment. In addition, the depolarization effects caused by a finite monochromator bandwidth is included in the model. Incorporation of the optical activity to the Mueller matrix model has required a development of rigorous theory based on appropriate constitutive equations. The generalized Yeh's matrix algebra to bianisotropic media has been used for the calculation of the eigenmodes propagation in chiral materials with reduced symmetry. Based on the applied method, the authors have proposed approximated analytical form of the Mueller matrix representing optically active waveplate and biplate and provided discussion on the analytical and numerical limits of the method.

In this paper, the authors characterize high-order quartz waveplates in the wide spectral range (from 193 to 1700 nm) using a commercial Mueller matrix ellipsometer RC2-DI-Woollam. They demonstrate that Mueller matrix ellipsometry is a powerful tool to obtain the waveplate retardation in a wide spectral range together with azimuthal angles of optical axes with good accuracy. Moreover, they deal with depolarization caused by a finite monochromator bandwidth, which is included in the model using incoherent averaging of Mueller matrices. The application of Lu–Chipman Mueller matrix decomposition to extract depolarization from data is also demonstrated. Finally, Lu–Chipman decomposition is used to demonstrate the presence of the optical activity in quartz, which one may misinterpret with incorrect alignment of the waveplate azimuth angle.

This diploma thesis deals with the reconstruction of the existing intersection of rounds I/9 and II/244, III/0085 near the village of Libeznice, in the Central Bohemia Region. The aim of the thesis is to increase the safety, fluency and comfort of transport. From the point of view of the driver's psychological certainty, the turning to the left of the secondary communication is problematic. Based on these facts, it is proposed to reconstruct the intersection at the junction of the turbo-circular junction.

The optical activity measurements have been widely performed using a simple polarimeter with a monochromatic source so far. This work introduces versatile and simple technique of the optical activity measurements using Mueller matrix spectroscopic ellipsometer (Woollam RC2-DI) with the spectral range from 0.73 eV to 6.42 eV (wavelength range from 193 nm to 1700 nm). First, we present the measurements of chiral solutions under constant temperature, where the dependences of the optical activity on solution concentration were determined. The measured spectra were compared to a dispersion model and the specific rotatory powers were calculated. Second, temperature-dependent measurements were performed using homemade, specially designed temperature control cells with 1 °C accuracy. The calculated specific rotatory powers were compared to commonly tabulated data for the wavelength of 589 nm with a good agreement, which proves us repeatability and robustness of the proposed method.