Plasmonic metafibers electro-optic modulators.

Digitalizing optical signals through electric driving signals, electro-optic modulators (EOMs) are one of the cardinal elements in modern optical communications. Most of current EOM devices are targeting on-chip integrations, which routinely suffer from high coupling losses, complex optical alignments and single-band operations. In this study, we for the first time integrate a lumped EOM device on the endfaces of a single-mode optical fiber jumper for fast amplitude modulations. Profiting from ultrathin and high quality-factor plasmonic metasurfaces, nanofabrication-friendly and highly efficient EO polymers and coupling-free connections with fiber networks, our EOM is demonstrated to allow dual-band operations (telecom O band and S band) and high-speed modulations (~1 GHz at a bias voltage of ±9 V). This work offers an avenue to 'plug-and-play' implementations of EO devices and ultracompact "all-in-fibers" optical systems for communications, imaging, sensing and many others.

Degradable silk-based soft actuators with magnetic responsiveness.

Soft actuators with stimuli-responsiveness have great potential in biomedical applications such as drug delivery and minimally invasive surgery. In this study, protein-based soft actuators with magnetic actuation are fabricated using naturally occurring silk proteins and synthesized Fe3O4 magnetic nanoparticles (NPs). Briefly, magnetic silk films are first prepared by solution casting of a mixture containing silk proteins, synthesized Fe3O4 NPs, and glycerol. The molecular structures of the magnetic silk films are characterized by FTIR spectroscopy, which show that the ß-sheet content in the films is about 20%. The mechanical tests show that the magnetic silk films can be stretched to over 200% under wet conditions and Young's modulus is estimated to be 4.89 ± 0.69 MPa, matching the stiffness of soft tissues. Furthermore, the enzymatic degradability, good biocompatibility, and in vivo X-ray visibility of the films are demonstrated by the in vitro enzymatic degradation test, in vivo biocompatibility test, and micro-CT imaging, respectively. Degradable silk-based soft actuators with magnetic responsiveness are successfully prepared by thermal forming or plastic molding of the magnetic silk films. The fabricated soft actuators can be actuated and move with precise locomotive gaits in solutions using a magnet. In addition, the retention of the soft actuators and localized drug delivery in gastrointestinal tracts by attaching a magnet to the abdominal skin are demonstrated using model systems. The degradable silk-based soft actuators provide many opportunities for improving current therapeutic strategies in biomedicine.

Natural polymer-based scaffolds for soft tissue repair.

Soft tissues such as skin, muscle, and tendon are easily damaged due to injury from physical activity and pathological lesions. For soft tissue repair and regeneration, biomaterials are often used to build scaffolds with appropriate structures and tailored functionalities that can support cell growth and new tissue formation. Among all types of scaffolds, natural polymer-based scaffolds attract much attention due to their excellent biocompatibility and tunable mechanical properties. In this comprehensive mini-review, we summarize recent progress on natural polymer-based scaffolds for soft tissue repair, focusing on clinical translations and materials design. Furthermore, the limitations and challenges, such as unsatisfied mechanical properties and unfavorable biological responses, are discussed to advance the development of novel scaffolds for soft tissue repair and regeneration toward clinical translation.

Electro-optic polymer and silicon nitride hybrid spatial light modulators based on a metasurface.

Spatial light modulators (SLMs) are important for various applications in photonics, such as near-infrared imaging, beam steering and optical communication. After decades of advances, current commercial devices are typically limited to kilohertz modulating speeds. To realize higher operating speeds, an electro-optic (EO) polymer and silicon nitride hybrid SLM has been demonstrated in this work. We utilize a specially designed metasurface to support a relatively high quality resonance and simultaneously confine most of the incident light in the active EO polymer layer. Combing with the high EO coefficient of the polymer, a clear modulation at 10 MHz with a driving voltage of Vp-p=±10 V has been observed in the proof-of-concept device. Our first-generation device leaves vast room for further improvement and may open an attractive route towards compact SLM with an RF modulation higher than 100 GHz.

Gas environment independent temperature sensor via double-metal surface plasmon resonance.

As the sensitivity of the optical temperature sensor increases, one of the most important noise sources may be from the fluctuation of the surrounding gas environment (refractive index change). In this work, we have designed and fabricated an optical temperature sensor with a device size of 15 µm2. The sensor is constructed by a titanium dioxide grating on top of a double-metal surface plasmon resonance (SPR) structure. Our design can provide minimal gas environment dependence without compromising the performance in terms of temperature sensitivity. In addition, the design also facilitates a generous dimensional tolerance in the device fabrication. Based on the design, a proof-of-concept device has been fabricated and characterized. The obtained sensitivity of the fabricated sensor reaches 135 pm/℃. Meanwhile, the measured resonance wavelength shift is ∼0.004 pm in different gases (air, CH4, and CO2). The presented temperature sensor should be convenient and valuable for high-accuracy temperature measurements and integrated opto-electronic sensing chips.

Design and theoretical characterization of high speed metasurface modulators based on electro-optic polymer.

Metasurfaces have attracted extraordinary interest in achieving novel, ultrathin and compact photonic devices. To date, however, the realization of electrically tunable high-speed metasurfaces remains a great challenge. In this work, we present an electro-optic (EO) polymer/silicon hybrid metasurface modulator with an estimated 3dB modulation bandwidth up to 118 GHz. The specially designed metasurface utilizes a broken in-plane inversion symmetry structure to generate a high-Q resonance. The high-Q property enhances the EO modulation effect, so that a 16 dB extinction ratio is theoretically verified under a driving voltage Vp-p of 4V. The pulse modulation results in an ultra-fast single-lane data rates up to 300 Gbps driven by a low RF power. The presented modulator should be applicable for high-speed and low-energy intelligent tunable metasurface, space optical communication and so on.

Nitrogen-Centered Concave Molecules with Double Fused Pentagons.

Distinctive concave compounds bearing a nitrogen core and double fused pentagons were synthesized with a palladium-catalyzed intramolecular coupling of 1-chloro-8 H-indolo[3,2,1- de]acridine as the key step. Structural analysis confirmed the formation of bowl-shaped molecules. Experimental characterizations and theoretical calculations reveal the incorporation of nitrogen is crucial to alleviate the pentagon fusing strain, as well as in property regulation.

A novel 3D heteropoly blue type photo-Fenton-like catalyst and its ability to remove dye pollution.

A environment-friendly 3D inorganic heteropoly blue (HPB) Ba2Na2 [HPWV4WVI8O40]·26H2O was directly synthesized by hydrothermal method and characterized by means of ICP, IR, XPS, X-ray single crystal and X-ray powder diffraction. It was an efficient heterogeneous photo-Fenton-like catalyst to degrade anionic dye methyl orange under visible light irradiation. It removed cationic dyes methylene blue in neutral environment and rhodamine B in acidic condition via flocculation. The removal efficiency of methylene blue and rhodamine B by flocculation was more than 95%. Moreover, it could degrade methyl orange and flocculate rhodamine B at the same time. For MO and MO-RhB solutions, the degradation rates of MO in 60 min were 85.5% and 49.1%, respectively. Furthermore, the possible pathways for the production of active species in the MO degradation reaction were discussed. This is the first HPB constructed with 4e-reduced phosphotungstate, Ba and Na ions, having the properties of photo-Fenton-like catalyst and flocculant.

A heteropoly blue as environmental friendly material: An excellent heterogeneous Fenton-like catalyst and flocculent.

The first 3D heteropoly blue Ba2Na4[SiW4VW8VIO40]·19H2O (1) as heterogeneous Fenton-like catalyst and flocculent was hydrothermally synthesized and fully characterized by various methods 1 was an efficient Fenton-like catalyst for degradation of phenol with degradation rate of 92.1% (visible light irradiation), and 89.0% (no light) in 90min, respectively. The degradation efficiency of anionic dye methyl orange was 97.0% in 5min, when 1 was used as photo-Fenton-like catalyst under visible light. And 1 was a nice flocculent for cationic dyes methylene blue and rhodamine B, the removal rates were both above 95%. Moreover, 1 could degrade methyl orange and flocculate rhodamine B at the same time, but the degradation rate decreased from 100% to 77.5% in 60min, while the flocculation of RhB in 10min was not affected.