Near-Field Coupled Integrable Two-Dimensional InSe Photosensor on Optical Fiber

Anisotropic van der Waals Tellurene-Based Multifunctional, Polarization-Sensitive, In-Line Optical Device

Polarization plays a paramount role in scaling the optical network capacity. Anisotropic two-dimensional (2D) materials offer opportunities to exploit optical polarization-sensitive responses in various photonic and optoelectronic applications. However, the exploration of optical anisotropy in fiber in-line devices, critical for ultrafast pulse generation and modulation, remains limited. In this study, we present a fiber-integrated device based on a single-crystalline tellurene nanosheet. Benefiting from the chiral-chain crystal lattice and distinct optical dichroism of tellurene, multifunctional optical devices possessing diverse excellent properties can be achieved. By inserting the in-line device into a 1.5 μm fiber laser cavity, we generated both linearly polarized and dual-wavelength mode-locking pulses with a degree of polarization of 98% and exceptional long-term stability. Through a twisted configuration of two tellurene nanosheets, we realized an all-optical switching operation with a fast response. The multifunctional device also serves as a broadband photodetector. Notably, bipolar polarization encoding communication at 1550 nm can be achieved without any external voltage. The device's multifunctionality and stability in ambient environments established a promising prototype for integrating polarization as an additional physical dimension in fiber optical networks, encompassing diverse applications in light generation, modulation, and detection.

Integration of multiple electronic components on a microfibre towards an emerging electronic textile platform

Electronic fibres have been considered one of the desired device platforms due to their dimensional compatibility with fabrics by weaving with yarns. However, a precise connecting process between each electronic fibre is essential to configure the desired electronic circuits or systems. Here, we present an integrated electronic fibre platform by fabricating electronic devices onto a one-dimensional microfibre substrate. Electronic components such as transistors, inverters, ring oscillators, and thermocouples are integrated together onto the outer surface of a fibre substrate with precise semiconductor and electrode patterns. Our results show that electronic components can be integrated on a single fibre with reliable operation. We evaluate the electronic properties of the chip on the fibre as a multifunctional electronic textile platform by testing their switching and data processing, as well as sensing or transducing units for detecting optical/thermal signals. The demonstration of the electronic fibre suggests significant proof of concepts for the realization of high performance with wearable electronic textile systems.

Towards further integration and miniaturization of e-textiles, in this work, authors demonstrate an integrated electronic fibre platform by fabricating multiple electronic components such as transistors, inverters, ring oscillators, and thermocouples onto the outer surface of a microfibre substrate.

Self-powered and high-performance all-fiber integrated photodetector based on graphene/palladium diselenide heterostructures

An all-fiber integrated photodetector is proposed and demonstrated by assembling a graphene/palladium diselenide (PdSe₂) Van der Waals heterostructure onto the endface of a standard optical fiber. A gold film is covered on the heterostructure working as an electrode and a mirror, which reflects back the unabsorbed residual light for further reusage. Owing to the low bandgap of PdSe₂, the all-fiber photodetector shows a broadband photoresponse from 650 to 1550 nm with a high photoresponsivity of 6.68×10⁴ AW^-1, enabling a low light detection of 42.5 pW. And the fastest temporal response is about 660 µs. Taking advantage of heterostructures, the photodetector can work in self-powered mode with the on/off ratio about 82. These findings provide new strategies for integrating two-dimensional materials into optical fibers to realize integrated all-fiber devices with multi-function applications.

Silica optical fiber integrated with two-dimensional materials: towards opto-electro-mechanical technology

In recent years, the integration of graphene and related two-dimensional (2D) materials in optical fibers have stimulated significant advances in all-fiber photonics and optoelectronics. The conventional passive silica fiber devices with 2D materials are empowered for enhancing light-matter interactions and are applied for manipulating light beams in respect of their polarization, phase, intensity and frequency, and even realizing the active photo-electric conversion and electro-optic modulation, which paves a new route to the integrated multifunctional all-fiber optoelectronic system. This article reviews the fast-progress field of hybrid 2D-materials-optical-fiber for the opto-electro-mechanical devices. The challenges and opportunities in this field for future development are discussed.

n-type polyaniline hole-blocking layer for high-efficiency QDSC by one-pot electropolymerization and selective aprotic cation ([EMIM]+) doping

In the field of clean solar-to-current devices, the photoelectron transfer process is essential for photovoltaic conversion in the typical n-i-p solar-cell structure. With regard to the oriented injection and ejection of photoelectrons, the development of hole-blocking layer (HBL) materials with a high electron transfer capability are exceedingly desirable. Profiting from the distortion of the p-π electron cloud attracted by a doped aprotic cation, a modified n-type polyaniline (PANI) as the HBL of a photoanode has been successfully fabricated through a facial one-pot square-wave potentiostatic electropolymerization method. In terms of flat-band potential, charge-carrier concentration and device impedance, the synthesized n-type polyaniline layer doped by aprotic ionic liquid (AIL; [EMIM] [EtSO₄]) (AIL-PA layer) for quantum dot solar cells (QDSCs) directly facilitates the high electron carrying capacity as well as the electron transfer driving force. Furthermore, the n-type polyaniline layer doped by AIL ([EMIM] [EtSO₄]) (AIL-PA layer) has a widely matching band gap for electron exportation and improved photovoltaic performance of CdS_xSe_1-x QDSCs: the power conversion efficiency is 10.5% and the J _sc is 21.59 mA cm^-2 for the device with an AIL-PA HBL. The electron diffusion length L _D is 8.07 μm for the photoanode with AIL-PA I and 7.58 μm for the photoanode with AIL-PA II.

Biomolecular sensing by surface-enhanced Raman scattering of monolayer Janus transition metal dichalcogenide

In this work, we demonstrate that monolayer Janus MoSSe is an effective and universal platform for enhancing Raman signal and detecting biomolecules for the first time. The out-of-plane dipoles in monolayer Janus MoSSe redistribute charges of adsorbed biomolecules, polarize biomolecules and enhance their Raman vibrational intensity. The estimated Raman enhancement factor is higher than 10⁵, which is comparable with the highest reported enhancement factor for 2D substrates. The C-C stretching Raman peak around 1360 cm^-1 is used to indicate the glucose concentration, and its peak-integrated intensity increases linearly with the glucose concentration in the range of 1-10 mM. DFT calculations also confirm that charge redistribution in glucose induced by dipole interactions can enhance Raman intensity significantly when glucose molecules are adsorbed onto monolayer Janus MoSSe.

Development of highly efficient chemosensors for Cu2+ and N2H4 detection based on 2D polyaniline derivatives by template-free chemical polymerization method

Chemosensors play an important role in environmental protection, medical diagnosis and energy conservation. Although polyaniline and its derivatives and two-dimensional (2D) materials have been applied as chemosensors in many reports, the concept of two-dimensional (2D) polyaniline derivatives has not been achieved in chemosensors. Here, two kinds of two-dimensional (2D) polyaniline derivatives are designed and synthesized by template-free chemical polymerization. It can be found that these two two-dimensional (2D) chemosensors exhibit high selectivity and sensitivity to Cu²⁺ and N₂H₄. Moreover, it is noteworthy that one of the two-dimensional materials can achieve the limit of detection (LOD) of 45 nM and 8 nM for Cu²⁺ and N₂H₄, respectively. Especially, these results imply that this two-dimensional polyaniline derivative is promising as the chemosensor in sensing field.

Enhancing monolayer photoluminescence on optical micro/nanofibers for low-threshold lasing

Although monolayer transition metal dichalcogenides (TMDs) have direct bandgaps, the low room-temperature photoluminescence quantum yields (QYs), especially under high pump intensity, limit their practical applications. Here, we use a simple photoactivation method to enhance the room-temperature QYs of monolayer MoS₂ grown on to silica micro/nanofibers by more than two orders of magnitude in a wide pump dynamic range. The high-density oxygen dangling bonds released from the tapered micro/nanofiber surface are the key to this strong enhancement of QYs. As the pump intensity increases from 10^-1 to 10⁴ W cm^-2, our photoactivated monolayer MoS₂ exhibits QYs from ~30 to 1% while maintaining high environmental stability, allowing direct lasing with greatly reduced thresholds down to 5 W cm^-2. Our strategy can be extended to other TMDs and offers a solution to the most challenging problem toward the realization of efficient and stable light emitters at room temperature based on these atomically thin materials.