Recent years have witnessed an increasing interest in highly-efficient absorbers of visible light for the conversion of solar energy into electrochemical energy. This study presents a TiO2-Au bilayer that consists of a rough Au film under a TiO2 film, which aims to enhance the photocurrent of TiO2 over the whole visible region and may be the first attempt to use rough Au films to sensitize TiO2. Experiments show that the bilayer structure gives the optimal optical and photoelectrochemical performance when the TiO2 layer is 30 nm thick and the Au film is 100 nm, measuring the absorption 80–90% over 400–800 nm and the photocurrent intensity of 15 μA·cm−2, much better than those of the TiO2-AuNP hybrid (i.e., Au nanoparticle covered by the TiO2 film) and the bare TiO2 film. The superior properties of the TiO2-Au bilayer can be attributed to the rough Au film as the plasmonic visible-light sensitizer and the photoactive TiO2 film as the electron accepter. As the Au film is fully covered by the TiO2 film, the TiO2-Au bilayer avoids the photocorrosion and leakage of Au materials and is expected to be stable for long-term operation, making it an excellent photoelectrode for the conversion of solar energy into electrochemical energy in the applications of water splitting, photocatalysis and photosynthesis.

We report a one-step strategy for the formation of an artificial photosystem I, with an enhanced coenzyme regeneration rate.

Far-infrared radiation (FIR) possesses various promising properties that are beneficial to an individuals’ health. Exploring the interaction between fiber shapes and FIR performance is thought to be a significant means to develop highly-efficient FIR textile products. In this study, a non-additive triangular polyamide (PA) fiber showed excellent FIR properties in both theoretical simulation and experimental verification aspects. The triangular PA fiber affords a higher probability to facilitate large optical path difference, improving both FIR absorption and emission. Textiles woven with the specific triangular PA fiber achieved a remarkable emissivity of 91.85% and temperature difference of 2.11 Celsius, which is obviously superior to the reference circular fiber (86.72%, 1.52 Celsius). Considering the low cost, environmental stability, facile fabrication, as well as being environmentally friendly, this non-additive triangular PA fiber has great potential for high-performance and cost-effective FIR textiles in the future.

Artificial photosynthesis (APS) mimics natural photosynthesis (NPS) to store solar energy in chemical compounds for applications such as water splitting, CO2 fixation and coenzyme regeneration. NPS is naturally an optofluidic system since the cells (typical size 10 to 100 µm) of green plants, algae, and cyanobacteria enable light capture, biochemical and enzymatic reactions and the related material transport in a microscale, aqueous environment. The long history of evolution has equipped NPS with the remarkable merits of a large surface-area-to-volume ratio, fast small molecule diffusion and precise control of mass transfer. APS is expected to share many of the same advantages of NPS and could even provide more functionality if optofluidic technology is introduced. Recently, many studies have reported on optofluidic APS systems, but there is still a lack of an in-depth review. This article will start with a brief introduction of the physical mechanisms and will then review recent progresses in water splitting, CO2 fixation and coenzyme regeneration in optofluidic APS systems, followed by discussions on pending problems for real applications.

This paper reports a tunable in-plane optofluidic lens by continuously tuning a silicone oil-air interface from concave to convex using the dielectrophoresis (DEP) force. Two parallel glasses are bonded firmly on two sides by NOA 81(Norland Optical Adhesive 81) spacers, forming an open microfluidic channel. An ITO (indium tin oxide) strip and another unpatterned ITO layer are deposited on two glasses as the top and bottom electrodes. Initially, a capillary concave liquid-air interface is formed at the end of the open channel. Then the DEP force is enabled to continuously deform the interface (lens) from concave to convex. In the experiment, the focal length gradually decreases from about -1 mm to infinite and then from infinite to around + 1 mm when the driving voltage is increased from 0 V to 260 V. Particularly, the longitudinal spherical aberration (LSA) is effectively suppressed to have LSA < 0.04 when the lens is operated in the focusing state. This work is the first study of in-plane tunable lenses using the DEP force and possesses special merits as compared to the other reported tunable lenses that are formed by pumping different liquids or by temperature gradient, such as wide tunability, no need for continuous supply of liquids, low power consumption (~81 nJ per switching) due to the capacitor-type driving, and the use of only one type of liquid. Besides, its low aberration makes it favorable for light manipulation in microfluidic networks.

We present a method for the calculation of the beam quality factor of an aberrated laser beam. The closed-form equations are proved, and it is shown that the beam quality factor of an aberrated Gaussian beam depends directly on the Hermite coefficient of the wavefront, as well as the truncation ratio. Further numerical calculation proves that the proposed model leads to results matching those in published work.

This paper presents the device design and performance analysis of a novel design of planar optical cross-connect (OXC) using nematic liquid crystal (NLC) waveguides. It employs N × N switching matrix in cross-bar fabric. In each unit cell, the input light is set in either the transverse electric (TE) mode or the transverse magnetic (TM) mode by electrically reorienting the NLC in the waveguide. The light then enters a passive waveguide and is routed to different paths depending on the polarization state (TE/TM mode). A sample device of 8 × 8 OXC is analyzed for performance estimation, which predicts a maximum on-chip insertion loss of 3 dB, an average cross-talk of -40 dB, ~1 ms switching time, and 2 mm × 2 mm footprint. The proposed OXC is unique in the switching mechanism of polarization-dependent routing and allows non-blocking switching with high compactness and broad bandwidth. It is potential for optical circuit switching in data centers and optical communication networks.

Based on a mathematic model, the relation between the accuracy of the influence matrix and the performance of the wavefront correction is established. Based on the least squares method, a two-step system identification is proposed to improve the accuracy of the influence matrix, where the measurement noise can be suppressed and the nonlinearity of the deformable mirror can be compensated. The validity of the two-step system identification method is tested in the experiment, where improvements in wavefront correction precision as well as closed-loop control efficiency were observed.