Grating-lobe-free optical phased array with 2-D circular sparse array aperture and high-efficiency phase calibration.

An optical phased array (OPA) with 2-D circular sparse array aperture has been proposed and demonstrated in the silicon integrated photonic platform. The sparse distribution of the antenna array can realize no grating lobes in 2-D full field of view (FOV). To achieve fast and accurate phase calibration for OPA, an improved rotating element electric field vector algorithm based on golden section search method (GSS-REV) has also been proposed and verified.

Rational Design of Hierarchical Structure Electrodes to Suppress Shuttle Diffusion in Redox-Enhanced Supercapacitors.

In carbon-based supercapacitors, redox couples can effectively improve the energy density of supercapacitors; however, most redox couples still suffer from serious shuttle diffusion. Currently, there is no universal strategy to effectively constrain their shuttle diffusion. Therefore, developing a simple, effective, and universal method to suppress shuttle diffusion remains a great challenge.

Coaxial transceiving LiDAR based on a silicon photonic optical phased array.

A high performance optical phased array (OPA) combined with frequency-modulated continuous-wave (FMCW) technology is essential for coherent all-solid-state light detection and ranging (LiDAR). In this work, we propose and experimentally demonstrate a coaxial transceiver based on a single OPA for a LiDAR system, which releases the off-chip circulator and collimator. The proposed scheme is demonstrated on the commonly used silicon-on-insulator (SOI) platform.

An acid-chromic luminescent lanthanide metallogel for time-dependent information encryption and anti-counterfeiting.

Luminescent materials with dynamic color transformation demonstrate significant potential in advanced information encryption and anti-counterfeiting. In this study, we designed multi-color luminescent lanthanide metallogels featuring time-dependent color transformation. These materials are based on Förster resonance energy transfer (FRET) platforms, facilitating cascade energy transfer from the ligand 4,4',4''-[1,3,5-benzenetriyltris (carbonylimino)]trisbenzoic acid (HL) to Tb ions and subsequently to Sulforhodamine 101.

Polarization multiplexing silicon photonic optical phased array with a wide scanning range.

We propose and experimentally demonstrate a polarization multiplexed silicon optical phased array (OPA) with a wide scanning range. The two polarization states share the same power splitter tree and the phase shifter array. A polarization switch is introduced in front of the power splitter tree to manipulate the polarization state of the light in OPA.

Metabolic Responses to Manganese Toxicity in Soybean Roots and Leaves.

Soybean is one of the most crucial beans in the world. Although Mn (manganese) is a kind of important nutritive element helpful to plant growth and health, excess Mn is harmful to crops. Nevertheless, the effect of Mn toxicity on soybean roots and leaves metabolism is still not clear.

Low-loss and power-efficient phase shifter based on an optimized multimode spiral silicon waveguide.

Low-loss and energy-efficient phase shifters are an effective tool to reduce the power consumption of large-scale photonic integrated circuits. In this work, a low-loss and power-efficient thermo-optic phase shifter has been demonstrated on the silicon-on-insulator platform. The multimode spiral waveguide is optimized to obtain lower power consumption and low cross talk.

Transcriptome Sequencing Analysis of Root in Soybean Responding to Mn Poisoning.

Manganese (Mn) is among one of the essential trace elements for normal plant development; however, excessive Mn can cause plant growth and development to be hindered. Nevertheless, the regulatory mechanisms of plant root response to Mn poisoning remain unclear. In the present study, results revealed that the root growth was inhibited when exposed to Mn poisoning.

Grating lobe-free silicon optical phased array with periodically bending modulation of dense antennas.

A grating lobe-free silicon optical phased array with large field of view is demonstrated. Antennas with periodically bending modulation are spaced at half wavelength or less. The experimental results show that the crosstalk between adjacent waveguides is negligible at 1550 nm wavelength.

Manipulating leaky mode in silicon waveguides harnessing bound states in the continuum.

A low-loss ridge waveguide is proposed and demonstrated with a novel, to the best of our knowledge, bound state in the continuum (BIC)-based structure on the silicon-on-insulator (SOI) platform. The presented waveguide is designed appropriately to suppress TM-mode leakage, and has a theoretically low propagation loss of ∼0.0027 dB/cm at 1550 nm.

Ultra-broadband dual-polarization and arbitrary ratio power splitters based on Bezier curve optimized multimode interference.

We propose and demonstrate two types of 1 × 2 power splitters based on multimode interference (MMI), which are ultra-compact, fabrication friendly, and low loss. The contours of MMI and output tapers are optimized with Bezier curves, which can implement arbitrary ratio power splitters (ARPSs) and ultra-broadband dual-polarization power splitters (UDPSs). For ARPSs, the experimental results show that arbitrary power splitting ratios can be obtained with an average excess loss (EL) of 0.

Silicon optical phased array with calibration-free phase shifters.

Optical phased array (OPA) based on silicon photonics is considered as a promising candidate for realizing solid-state beam steering. However, the high refractive index contrast of the silicon waveguides leads to conventional silicon based OPA suffering from large random phase errors, which require complex post-processing such as time-consuming phase calibration. We propose and demonstrate a calibration-free silicon OPA with optimized optical waveguides width as well as the compact 90° waveguide bends beyond the single mode regime.

All-Solid-State Beam Steering via Integrated Optical Phased Array Technology.

Light detection and ranging (LiDAR), combining traditional radar technology with modern laser technology, has much potential for applications in navigation, mapping, and so on. Benefiting from the superior performance, an all-solid-state beam steering realized by integrated optical phased array (OPA) is one of the key components in the LiDAR system. In this review, we first introduce the basic principle of OPA for beam steering.

Polarization tunable color filters based on all-dielectric metasurfaces on a flexible substrate.

Structural color filters based on all-dielectric materials are considered to be promising alternatives to metal nanostructures due to significant advantages, such as high-quality resonance effects and low losses of Ohmic effects. We demonstrate a polarization tunable color filter based on all-dielectric metasurfaces, which is based on the arrays of asymmetric monocrystalline silicon nanoblocks on the flexible substrate. By adjusting the physical dimensions of nanoblocks, the filter can exhibit a variety of bright transmission colors.

On-chip simultaneous sensing of humidity and temperature with a dual-polarization silicon microring resonator.

It is still challenging to realize an on-chip optical sensor that can detect humidity and temperature at the same time. In this paper, we demonstrate a silicon-based dual-polarization micro-ring resonator (MRR) with a polyvinyl-alcohol (PVA) upper-cladding, which enables the simultaneous measurement of humidity and temperature. Due to the significant polarization-dependence of the silicon-on-insulator (SOI) nanophotonic waveguide, the transverse electric (TE) and transverse magnetic (TM) polarization modes have quite different sensitivities towards the changes of ambient relative humidity (RH) and temperature.

Toward a Brain-Inspired System: Deep Recurrent Reinforcement Learning for a Simulated Self-Driving Agent.

An effective way to achieve intelligence is to simulate various intelligent behaviors in the human brain. In recent years, bio-inspired learning methods have emerged, and they are different from the classical mathematical programming principle. From the perspective of brain inspiration, reinforcement learning has gained additional interest in solving decision-making tasks as increasing neuroscientific research demonstrates that significant links exist between reinforcement learning and specific neural substrates.

Polarization-insensitive silicon waveguide crossing based on multimode interference couplers.

A polarization-insensitive waveguide crossing based on multimode interference (MMI) couplers is proposed and demonstrated on a silicon-on-insulator (SOI) platform. By utilizing two orthogonal MMIs, the footprint of the device is about 23  μm×23  μm. The proposed device, easily fabricated with only one fully etched step, is characterized with low insertion losses and low crosstalks for both transverse-electric and transverse-magnetic polarizations from 1520 to 1610 nm bands.

Compact high-efficiency perfectly-vertical grating coupler on silicon at O-band.

A compact, high-efficiency grating coupler is demonstrated for interfacing a silicon waveguide and a perfectly-vertical fiber at O-band. The grating lies on a tilted silicon membrane for minimizing the reflections. Circular grating lines are adopted to shorten the overall device length to about 60μm.

High sensitivity temperature sensor based on cascaded silicon photonic crystal nanobeam cavities.

We present the design, fabrication and characterization of a high sensitivity temperature sensor based on cascaded silicon photonic crystal (PhC) nanobeam cavities. Two PhC nanobeam cavities, one with stack width modulated structure and the other one with parabolic-beam structure are utilized to increase the sensitivity. Most of the light is designed to be confined in the cladding and the core for these two cavities, respectively.