Enhancing the photoluminescence response from thick Ge-on-Si layers using the photonic crystals

More than an order of magnitude enhancement of the room-temperature photoluminescence (PL) signal from rather thick Ge layers grown on Si(001) was obtained by utilization of the two-dimensional photonic crystals (PhC). A set of PhCs with different periods and filling factors was fabricated and studied using a micro-PL spectroscopy. Optical features of the fabricated PhCs were also theoretically modeled using a rigorously coupled wave analysis which allowed to bring the observed peaks in the PL response into correlation with the different modes of PhC. In particular, we were able to associate the well-resolved peaks in the PL spectra with the optically active modes of the PhCs. The obtained results proved the possibility of using a homogeneously distributed active medium in PhCs without the formation of specially designed cavities in order to redistribute the internal emitted light into the required modes and efficiently extract it to the far field. The relative simplicity and higher tolerance to fabrication imperfections, as well as the large working area of such kind of PhCs as compared to PhCs with microcavities can be advantageous for creating a PhC-based Si-compatible light source for the telecom band.

Fluorescent nematic liquid crystalline oligomers with Reversible Texture and Photoluminescence response to Temperature

Fluorescent liquid crystalline in luminescent materials have attracted interest for their unique feature of fluorescence in response to external stimulus and their applicability in information security and anti-counterfeiting. Herein, fluorescent...

Reverse photoluminescence responses of Ln(iii) complexes to methanol vapor clarify the differentiated energy transfer pathway and potential for methanol detection and encryption

A VOC detection and optical encryption model based on the uncommon reverse photoluminescence response of isomorphic Eu(iii) and Tb(iii) complexes to MeOH vapor.

Mechanically controlled reversible photoluminescence response in all-inorganic flexible transparent ferroelectric/mica heterostructures

The ability to reversibly control the luminescent properties of functional materials with diverse external stimuli, such as an electric field, strain, and temperature, is crucial for designing high-performance optical devices. Here, we demonstrate that a purely mechanical strain in a flexible mica substrate triggered by bending can be used to dramatically modify the photoluminescence response of a Pr-doped Ba0.85Ca0.15Ti0.9Zr0.1O3 epitaxial thin film in a stable and repeatable manner with a large gauge factor of up to 6853. The strong dependence of the photoluminescence performance on the mechanical bending arises from strain-induced variations in the lattice symmetry of the host film and the local crystal field around the Pr3+. In particular, because of the nature of mica, the film structure exhibits excellent antifatigue characteristics after 104 bending cycles as well as high optical transparency in the range of 450–780 nm. This study provides a viable route for exploring the correlation between structural symmetry and photoluminescence in ferroelectric thin-film systems and offers new possibilities for developing all-inorganic, reconfigurable, transparent and flexible light sources, photodetectors, and wearable sensors.