Current clinical management of vocal fold (VF) scarring produces inconsistent and often suboptimal results. Researchers are investigating a number of alternative treatments for VF lamina propria (LP) scarring, including designer implant materials for functional LP regeneration. In the present study, we investigate the effects of the initial scaffold elastic modulus and mesh size on encapsulated VF fibroblast (VFF) extracellular matrix (ECM) production toward rational scaffold design. Polyethylene glycol diacrylate (PEGDA) hydrogels were selected for this study since their material properties, including mechanical properties, mesh size, degradation rate and bioactivity, can be tightly controlled and systematically modified. Porcine VFF were encapsulated in four PEGDA hydrogels with degradation half lives of ~25 days and initial elastic compressive moduli ranging from ~30 to 100 kPa and initial mesh sizes ranging from ~9 to 27 nm. After 30 days of static culture, VFF ECM production and phenotype in each formulation was assessed biochemically and histologically. Sulfated glycosaminoglycan synthesis increased in similar degree with both increasing initial modulus and decreasing initial mesh size. In contrast, elastin production decreased with increasing initial modulus but increased with decreasing initial mesh size. Both collagen deposition and the induction of a myofibroblastic phenotype depended strongly on initial mesh size but appeared largely unaffected by variations in initial modulus. The present results indicate that scaffold mesh size warrants further investigation as a critical regulator of VFF ECM synthesis. Furthermore, this study validates a systematic and controlled approach for analyzing VFF response to scaffold properties, which should aid in rational scaffold selection/design.

Directional light scattering is important in basic research and real applications. This area has been successfully downscaled to wavelength and subwavelength scales with the development of optical antennas, especially single-element nanoantennas. Here, by adding an auxiliary resonant structure to a single-element plasmonic nanoantenna, we show that the highly efficient lowest-order antenna mode can be effectively transferred into inactive higher-order modes. On the basis of this mode conversion, scattered optical fields can be well manipulated by utilizing the interference between different antenna modes. Both broadband directional excitation of surface plasmon polaritons (SPPs) and inversion of SPP launching direction at different wavelengths are experimentally demonstrated as typical examples. The proposed strategy based on mode conversion and mode interference provides new opportunities for the design of nanoscale optical devices, especially directional nanoantennas.

The manipulation of light propagation is a basic subject in optics and has many important applications. With the development of nano-optics, this area has been downscaled to wavelength or even subwavelength scales. One of the most efficient ways to control light propagation is to exploit interference effects. Here, by manipulating the interference between two nanogrooves on a metal surface, we realize a submicron broadband surface-plasmon-polariton (SPP) unidirectional coupler. More importantly, we find an anomalous bandwidth shrinking behavior in the proposed SPP unidirectional coupler as the groove separation is down to a subwavelength scale of one-quarter of the SPP wavelength. This abnormal behavior is well explained by considering the contribution of the near-field quasi-cylindrical waves in addition to the interference of propagating SPPs and the dispersion effects of individual grooves. Such near-field effects provide new opportunities for the design of ultracompact optical devices.

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Linear-optical logic gates have the potential to be the bases of the next-generation information technology (IT) because of the low power consumption and rapid response. This study proposes a general theoretical model to obtain the optimal solutions for linear-optical logic gates. All common logic gates (AND, OR, NOT, NAND, NOR, XOR, and XNOR) are experimentally demonstrated with one single sample structure based on ultracompact plasmonic waveguides. The measured intensity contrast ratio between the outputlogic "1" and "0" states reaches 28 dB for the OR gate and 9.4 dB for the AND gate, thereby approaching the theoretical maximum of infinity and 9.5 dB, respectively. The proposed logic gates provide uniform output intensities for identical output logics when the input logics are different. The measured intensity discrepancies are below 1% for the three output-logic "1" states of the OR gate and the three output-logic "0" states of the AND gate. This phenomenon is favored in practical applications and the cascading of logic gates. The proposed universal linear-optical logic gate with maximal intensity contrast ratios may find important future applications in the field of IT.