Comparison of grain cadmium and arsenic concentration between main and ratoon crop in rice ratooning system.

Rice ratooning system is becoming increasingly important for food security in China, however, information on grain cadmium (Cd) and arsenic (As) levels is lacking. We collected grain samples of main crop (MC) and ratoon crop (RC) from five sites, where the same eleven varieties were planted, and determined the Cd and As concentration in brown rice. Results showed that differences in grain Cd level between MC and RC were inconsistent across experimental sites, although the average value was comparable.

Physics-informed recurrent neural network for time dynamics in optical resonances.

Resonance structures and features are ubiquitous in optical science. However, capturing their time dynamics in real-world scenarios suffers from long data acquisition time and low analysis accuracy due to slow convergence and limited time windows. Here we report a physics-informed recurrent neural network to forecast the time-domain response of optical resonances and infer corresponding resonance frequencies by acquiring a fraction of the sequence as input.

InP high power monolithically integrated widely tunable laser and SOA array for hybrid integration.

We present a monolithic InP-based photonic integrated circuit (PIC) consisting of a widely tunable laser master oscillator feeding an array of integrated semiconductor optical amplifiers that are interferometrically combined on-chip in a single-mode waveguide. We demonstrate a stable and efficient on-chip coherent beam combination and obtain up to 240 mW average power from the monolithic PIC, with 30-50 kHz Schawlow-Townes linewidths and >180 mW average power across the extended C-band. We also explored hybrid integration of the InP-based laser and amplifier array PIC with a high quality factor silicon nitride microring resonator.

Design of a broadband GeSi electro-absorption modulator based on the Franz-Keldysh effect with thermal tuning.

We present the design of an adiabatic taper coupled GeSi electro-absorption modulator, which is based on Franz-Keldysh effect. The device has an active region of 0.8×50 µm, an extinction ratio of more than 6 dB and an insertion loss less than 3 dB at the wavelength of 1550 nm.

Effect of Yiqi Huayu Jiedu decoction on stages II and III gastric cancer: A multicenter, prospective, cohort study.

Background: This study aimed to explore the effect of YHJD (Yiqi Huayu Jiedu decoction) in patients with stages II and III gastric cancer.

Methods: A multicenter, prospective, cohort study was conducted in Jiangsu Province Hospital of Traditional Chinese Medicine, Jiangsu Cancer Hospital, Nanjing Drum Tower Hospital, People's Liberation Army Bayi Hospital, Changzhou Traditional Chinese Medicine Hospital, Changzhou Tumor Hospital, Traditional Chinese Medicine Hospital of Kunshan, Yangzhou Hospital of Traditional Chinese Medicine, and Yixing Tumor Hospital. A total of 489 patients with stage II or III gastric cancer were enrolled after radical gastrectomy.

Characterizing pump line phase offset of a single-soliton Kerr comb by dual comb interferometry.

We report phase retrieval of a single-soliton Kerr comb using electric field cross-correlation implemented via dual-comb interferometry. The phase profile of the Kerr comb is acquired through the heterodyne beat between the Kerr comb and an electro-optic comb with a pre-characterized phase profile. The soliton Kerr comb has a nearly flat phase profile, and the pump line is observed to show a phase offset which depends on the pumping parameters.

Observation of Breathing Dark Pulses in Normal Dispersion Optical Microresonators.

Breathers are localized waves in nonlinear systems that undergo a periodic variation in time or space. The concept of breathers is useful for describing many nonlinear physical systems including granular lattices, Bose-Einstein condensates, hydrodynamics, plasmas, and optics. In optics, breathers can exist in either the anomalous or the normal dispersion regimes, but they have only been characterized in the former, to our knowledge.

Controlling evanescent waves using silicon photonic all-dielectric metamaterials for dense integration.

Ultra-compact, densely integrated optical components manufactured on a CMOS-foundry platform are highly desirable for optical information processing and electronic-photonic co-integration. However, the large spatial extent of evanescent waves arising from nanoscale confinement, ubiquitous in silicon photonic devices, causes significant cross-talk and scattering loss. Here, we demonstrate that anisotropic all-dielectric metamaterials open a new degree of freedom in total internal reflection to shorten the decay length of evanescent waves.

High-order coherent communications using mode-locked dark-pulse Kerr combs from microresonators.

Microresonator frequency combs harness the nonlinear Kerr effect in an integrated optical cavity to generate a multitude of phase-locked frequency lines. The line spacing can reach values in the order of 100 GHz, making it an attractive multi-wavelength light source for applications in fiber-optic communications. Depending on the dispersion of the microresonator, different physical dynamics have been observed.

50-GHz-spaced comb of high-dimensional frequency-bin entangled photons from an on-chip silicon nitride microresonator.

Quantum frequency combs from chip-scale integrated sources are promising candidates for scalable and robust quantum information processing (QIP). However, to use these quantum combs for frequency domain QIP, demonstration of entanglement in the frequency basis, showing that the entangled photons are in a coherent superposition of multiple frequency bins, is required. We present a verification of qubit and qutrit frequency-bin entanglement using an on-chip quantum frequency comb with 40 mode pairs, through a two-photon interference measurement that is based on electro-optic phase modulation.

Long-haul coherent communications using microresonator-based frequency combs.

Microresonator-based frequency combs are strong contenders as light sources for wavelength-division multiplexing (WDM). Recent experiments have shown the potential of microresonator combs for replacing a multitude of WDM lasers with a single laser-pumped device. Previous demonstrations have however focused on short-distance few-span links reaching an impressive throughput at the expense of transmission distance.

Direct soliton generation in microresonators.

We investigate, numerically and experimentally, the effect of thermo-optical (TO) chaos on soliton generation dynamics in microresonators. Numerical simulations that include the thermal dynamics show that the generated solitons can either survive or annihilate when the pump laser is scanned from blue to red and then stop at a fixed wavelength; the outcome is stochastic and is strongly related to the number of solitons generated. The random fluctuations of the cavity resonance occurring under TO chaos are also found to trigger delayed spontaneous soliton generation after the laser scan ends, which could enable soliton excitation with slow laser tuning speed.

Dispersion engineering and frequency comb generation in thin silicon nitride concentric microresonators.

Kerr nonlinearity-based frequency combs and solitons have been generated from on-chip microresonators. The initiation of the combs requires global or local anomalous dispersion which leads to many limitations, such as material choice, film thickness, and spectral ranges where combs can be generated, as well as fabrication challenges. Using a concentric racetrack-shaped resonator, we show that such constraints can be lifted and resonator dispersion can be engineered to be anomalous over moderately broad bandwidth.

Solasodine inhibits human colorectal cancer cells through suppression of the AKT/glycogen synthase kinase-3β/β-catenin pathway.

Solasodine is a main active component isolated from Solanum incanum L. that performs a wide range of functions containing anti-oxidant, anti-infection, and neurogenesis promotion. In this study, we explored the influence of solasodine on three types of human colorectal cancer (CRC) cell lines.

Second-harmonic-assisted four-wave mixing in chip-based microresonator frequency comb generation.

Simultaneous Kerr comb formation and second-harmonic generation with on-chip microresonators can greatly facilitate comb self-referencing for optical clocks and frequency metrology. Moreover, the presence of both second- and third-order nonlinearities results in complex cavity dynamics that is of high scientific interest but is still far from being well-understood. Here, we demonstrate that the interaction between the fundamental and the second-harmonic waves can provide an entirely new way of phase matching for four-wave mixing in optical microresonators, enabling the generation of optical frequency combs in the normal dispersion regime under conditions where comb creation is ordinarily prohibited.

Soliton repetition rate in a silicon-nitride microresonator.

The repetition rate of a Kerr comb composed of a single soliton in an anomalous group velocity dispersion silicon-nitride microcavity is measured as a function of pump frequency. By comparing operation in the soliton and non-soliton states, the contributions from the Raman soliton self-frequency shift (SSFS) and the thermal effects are evaluated; the SSFS is found to dominate the changes in the repetition rate, similar to silica cavities. The relationship between the changes in the repetition rate and the pump frequency detuning is found to be independent of the nonlinearity coefficient and dispersion of the cavity.

Observation of Fermi-Pasta-Ulam Recurrence Induced by Breather Solitons in an Optical Microresonator.

We present, experimentally and numerically, the observation of Fermi-Pasta-Ulam recurrence induced by breather solitons in a high-Q SiN microresonator. Breather solitons can be excited by increasing the pump power at a relatively small pump phase detuning in microresonators. Out of phase power evolution is observed for groups of comb lines around the center of the spectrum compared to groups of lines in the spectral wings.

Intracavity characterization of micro-comb generation in the single-soliton regime.

Soliton formation in on-chip micro-comb generation balances cavity dispersion and nonlinearity and allows coherent, low-noise comb operation. We study the intracavity waveform of an on-chip microcavity soliton in a silicon nitride microresonator configured with a drop port. Whereas combs measured at the through port are accompanied by a very strong pump line which accounts for >99% of the output power, our experiments reveal that inside the microcavity, most of the power is in the soliton.

Strip-slot direct mode coupler.

We present a direct strip-slot waveguide mode coupler without any auxiliary structures. Contrary to popular belief, an apparent mode mismatch between strip and slot waveguide does not deteriorate conversion efficiency. Separated electric and magnetic field distributions in a slot waveguide lead to highly efficient modal coupling in the direct strip-slot coupler and result in high conversion efficiency.

Broadband second-harmonic phase-matching in dispersion engineered slot waveguides.

Parametric optical nonlinearities are usually weak and require both high optical field intensity and phase-matching. Micro/nanophotonics, with strong confinement of light in waveguides of nanometer-scale cross-sections, can provide high field intensity, but is still in need of a solution for phase-matching across a broad bandwidth. In this article, we show that mode-coupling in slot waveguides can engineer the waveguide modal dispersion, and with proper choice of materials, can achieve on-chip broadband second-harmonic phase-matching.

Thermal tuning of Kerr frequency combs in silicon nitride microring resonators.

Microresonator based Kerr frequency comb generation has many attractive features, including ultrabroad spectra, chip-level integration, and low power consumption. Achieving precise tuning control over the comb frequencies will be important for a number of practical applications, but has been little explored for microresonator combs. In this paper, we characterize the thermal tuning of a coherent Kerr frequency comb generated from an on-chip silicon nitride microring.

Mode-evolution-based polarization rotation and coupling between silicon and hybrid plasmonic waveguides.

Hybrid plasmonic (HP) modes allow strong optical field confinement and simultaneously low propagation loss, offering a potentially compact and efficient platform for on-chip photonic applications. However, their implementation is hampered by the low coupling efficiency between dielectric guided modes and HP modes, caused by mode mismatch and polarization difference. In this work, we present a mode-evolution-based polarization rotation and coupling structure that adiabatically rotates the TE mode in a silicon waveguide and couples it to the HP mode in a strip silicon-dielectric-metal waveguide.

Ligand-Free Pd-Catalyzed Double Carbonylation of Aryl Iodides with Amines to α-Ketoamides under Atmospheric Pressure of Carbon Monoxide and at Room Temperature.

A general Pd-catalyzed double carbonylation of aryl iodides with secondary or primary amines to produce α-ketoamides at atmospheric CO pressure has been developed. This transformation proceeds successfully even at room temperature and in the absence of any ligand and additive. A wide range of aryl iodides and amines can be coupled to the desired α-ketoamides in high yields with excellent chemoselectivities.

A silicon-on-insulator polarization diversity scheme in the mid-infrared.

We propose a silicon-on-insulator (SOI) polarization diversity scheme in the mid-infrared wavelength range. In consideration of absorption loss in silicon dioxide (SiO), the polarization splitter-rotator (PSR) is designed and optimized with silicon nitride (SiN) upper-cladding and SiO lower-cladding. This asymmetry allows the PSR, which consists of mode-conversion tapers and subsequent mode-sorting asymmetric Y-junctions, to be fabricated with a simple one-step etching process.

Polarization rotation and coupling between silicon waveguide and hybrid plasmonic waveguide.

We present a polarization rotation and coupling scheme that rotates a TE(0) mode in a silicon waveguide and simultaneously couples the rotated mode to a hybrid plasmonic (HP(0)) waveguide mode. Such a polarization rotation can be realized with a partially etched asymmetric hybrid plasmonic waveguide consisting of a silicon strip waveguide, a thin oxide spacer, and a metal cap made from copper, gold, silver or aluminum. Two implementations, one with and one without the tapering of the metal cap are presented, and different taper shapes (linear and exponential) are also analyzed.