Media 3: A 2.95 GHz, femtosecond passive harmonic mode-locked fiber laser based on evanescent field interaction with topological insulator film

Originally published in Optics Express on 12 January 2015 (oe-23-1-154

Media 1: A 2.95 GHz, femtosecond passive harmonic mode-locked fiber laser based on evanescent field interaction with topological insulator film

Originally published in Optics Express on 12 January 2015 (oe-23-1-154

Media 4: A 2.95 GHz, femtosecond passive harmonic mode-locked fiber laser based on evanescent field interaction with topological insulator film

Originally published in Optics Express on 12 January 2015 (oe-23-1-154

Gate-Programmable Electro-Optical Addressing Array of Graphene-Coated Nanowires with Sub-10 nm Resolution

The rapid development of highly integrated photonic circuits has been driving electro-optic (EO) devices to increasingly compact sizes, with the perspective of being able to control light at the nanoscale. However, tunability with spatial resolution below 10 nm scale with conventional approaches, such as metallic nanowires, remains a challenge. Here, we show a graphene-coated nanowire system aiming at beam spatial modulation at a deeply subwavelength scale. By analytically and numerically investigating the eigenmodal properties of this system, we found that beam power can propagate along either a swinging or a helical path in the hybrid nanowire. In particular, the period of the swing beam and the chirality and period of the helix beam can be flexibly controlled by tuning the chemical potential of graphene via the gate voltage. Significantly, due to its good modal confinement, such a beam can be independently manipulated even in the presence of another nanowire at a separation of 40 nm, which opens a realistic path toward gate-programmable EO addressing or data storage with ultrahigh density (64 terabyte/μm). At the same time, by fulfilling the phase matching condition between the two supported guided modes operating at different wavelengths, either a full band or band-tunable terahertz wave at the nanoscale may be achieved by nonlinear difference frequency generation. Our proposed hybrid nanowire system opens interesting potentials to accomplish gate-programmable EO devices at sub-10 nm scale

Laser Direct Writing of Tree-Shaped Hierarchical Cones on a Superhydrophobic Film for High-Efficiency Water Collection

Directional water collection has stimulated a great deal of interest because of its potential applications in the field of microfluidics, liquid transportation, fog harvesting, and so forth. There have been some bio or bioinspired structures for directional water collection, from one-dimensional spider silk to two-dimensional star-like patterns to three-dimensional <i>Nepenthes alata</i>. Here we present a simple way for the accurate design and highly controllable driving of tiny droplets: by laser direct writing of hierarchical patterns with modified wettability and desired geometry on a superhydrophobic film, the patterned film can precisely and directionally drive tiny water droplets and dramatically improve the efficiency of water collection with a factor of ∼36 compared with the original superhydrophobic film. Such a patterned film might be an ideal platform for water collection from humid air and for planar microfluidics without tunnels