Linear Dichroism Conversion in Quasi‐1D Perovskite Chalcogenide

Abstract

Anisotropic photonic materials with linear dichroism property are crucial components in many sensing, imaging and emerging light based quantum communication applications. Such materials play an important role as polarizers, filters, wave-plates, phase-matching elements in photonic devices and circuits. Conventional crystalline materials with optical anisotropy typically show strong unidirectional linear dichroism over a broad wavelength range and even bandgap variations along different crystal directions. On the other hand, the linear dichroism conversion phenomenon -the orthogonal switch in the principle dichroism axis of the material across different optical wavelengthhas not been observed in crystalline materials. Here, we report the investigation of the unique linear dichroism conversion phenomenon in quasi-one-dimensional (quasi-1D) hexagonal perovskite chalcogenide BaTiS3. The material shows record level of optical anisotropy within the visible wavelength range. In contrast to conventional anisotropic optical materials, the linear dichroism polarity in BaTiS3 makes an orthogonal change at an optical wavelength corresponding to the photon energy of 1.78 eV. First principle calculations reveal that this anomalous linear dichroism conversion behavior originates from different selection rules of the optical transitions from the parallel bands in the BaTiS3 material. Wavelength dependent polarized Raman spectroscopy further confirms this phenomenon. Such material with linear dichroism conversion property can facilitate new ability to control and sense the energy, phase, and polarization of light, and lead to novel photonic devices such as polarization-wavelength selective detectors and lasers for multispectral imaging, sensing and optical communication applications.

Giant anisotropic photonics in the 1D van der Waals semiconductor fibrous red phosphorus

“…Remarkably, the linear dichroism of PL peak P6 can reach more than 90%, being comparable to the highest values obtained among the well-known quasi-1D van der Waals materials (Fig. 3i ) 3 , 6 , 50 – 55 . The linear dichroism of other PL peaks can be found in Supplementary Fig.…”

“…The results further confirm the highly anisotropic PL emission. To quantify the magnitude of PL anisotropy, we define the degree of linear dichroism as , where I c o ( I cross ) denotes the PL intensity detected copolarized (cross-polarized) to the laser polarization 8 , 49 , 50 . The inset of Fig.…”

Emerging low-dimensional materials for mid-infrared detection

“…The anisotropic absorption edges were also certified through density-functional calculations of absorption coefficients for polarized light along the intrachain and interchain directions. More detailed study from Wu et al revealed a unique linear dichroism conversion behavior in the quasi-1D BaTiS3 at an optical wavelength of 0.7 μm, corresponding to the excitation photon energy of 1.78 eV [48], which is due to polarization-resolved localized joint density of states of the crystal resulting from the parallel energy bands in this optical transition energy range. Moreover, an unprecedentedly giant and broadband birefringence of up to 0.76 was confirmed in the mid-to long-wave infrared ranging from 8 to 16.7 μm.…”

“…6(a) [16]. Ideally, the polarization dependent absorption can be described as, η(θ) = ηmaxcos 2 (θ) + ηminsin 2 (θ), where θ is the angle with the main axis, which has the strongest absorption (ηmax), ηmax is the absorption along the second axis that is orthogonal to the main axis for all the materials discussed here [18,37,40,46,48,183]. For the other materials with lower symmetry, such as ReS2 [184] and ReSe2 [185], the main axis and second axis are no longer orthogonal, thus, it needs new equation to describe the angle-dependent absorption.…”

“…Low-dimensional semiconductor, such as black phosphors (BP) [37][38][39], black arsenic phosphorus (b-AsP) [40][41][42], Tellurene (Te) [43][44][45] and BaTiS3 (BTS) [46][47][48], can enable mid-IR detectors with high responsivity and detectivity [16-18, 21, 24, 25]. Due to their self-terminated material surface resulting from their layered van der Waals (vdW) lattices, most of these materials can be easily integrated with the silicon platform and processed with the standard nanofabrication, resulting in good CMOS compatibility [43,46,[49][50][51].…”