Experimental observation of optical differentiation and optical Hilbert transformation using a single SOI microdisk chip.

Optical differentiation and optical Hilbert transformation play important roles in communications, computing, information processing and signal analysis in optical domain offering huge bandwidth. Meanwhile, silicon-based photonic integrated circuit is one of the most promising candidates for all-optical signal processing due to its intrinsic advantages of low power consumption, compact footprint, ultra-high speed and compatibility with electronic integrated circuits. In this study, we analyze the interrelation between first-order optical differentiation and optical Hilbert transformation and then experimentally demonstrate a feasible integrated scheme which can simultaneously function as first-order optical differentiation and optical Hilbert transformation based on a single microdisk resonator.

All-optical 10 Gb/s AND logic gate in a silicon microring resonator.

An all-optical AND logic gate in a single silicon microring resonator is experimentally demonstrated at 10 Gb/s with 50% RZ-OOK signals. By setting the wavelengths of two intensity-modulated input pumps on the resonances of the microring resonator, field-enhanced four-wave mixing with a total input power of only 8.5 dBm takes place in the ring, resulting in the generation of an idler whose intensity follows the logic operation between the pumps.

Silicon based polarization insensitive filter for WDM-PDM signal processing.

We propose and fabricate a novel circuit that combines two two-dimensional (2D) grating couplers and a microring resonator (MRR). According to the polarization states, one 2D grating coupler first splits the input signals into two orthogonal paths, which co-propagate in the loop and share a common MRR, and then the two paths are combined together by the other 2D grating coupler. The proposed circuit is polarization insensitive and can be used as a polarization insensitive filter.

High-order all-optical differential equation solver based on microring resonators.

We propose and experimentally demonstrate a feasible integrated scheme to solve all-optical differential equations using microring resonators (MRRs) that is capable of solving first- and second-order linear ordinary differential equations with different constant coefficients. Employing two cascaded MRRs with different radii, an excellent agreement between the numerical simulation and the experimental results is obtained. Due to the inherent merits of silicon-based devices for all-optical computing, such as low power consumption, small size, and high speed, this finding may motivate the development of integrated optical signal processors and further extend optical computing technologies.

SOI based ultracompact polarization insensitive filter for PDM signal processing.

We propose and fabricate a scheme that combines a two-dimensional (2D) grating coupler and a delay interferometer (DI) in a loop configuration. According to the polarization states, the 2D grating coupler first splits the input signals into two paths, which copropagate in the loop and share a common DI, and then combines the two paths together to the same input port. The proposed device is polarization insensitive and can be used for polarization division multiplexed (PDM) signal processing.

Efficient second harmonic generation from mid-infrared to near-infrared regions in silicon-organic hybrid plasmonic waveguides with small fabrication-error sensitivity and a large bandwidth.

We theoretically investigate the quadratic nonlinear property of a silicon-organic hybrid plasmonic waveguide with a thin polymer layer deposited on top of a silicon slab and covered by a metal cap. Due to the hybridization property of the waveguide modes, efficient phase-matched second harmonic generation (SHG) from mid-infrared (IR) (~3.1 μm) to near-IR (~1.

An optically tunable wideband optoelectronic oscillator based on a bandpass microwave photonic filter.

An optoelectronic oscillator (OEO) with wideband frequency tunability and stable output based on a bandpass microwave photonic filter (MPF) has been proposed and experimentally demonstrated. Realized by cascading a finite impulse response (FIR) filter and an infinite impulse response (IIR) filter together, the tunable bandpass MPF successfully replaces the narrowband electrical bandpass filter in a conventional single-loop OEO and serves as the oscillating frequency selector. The FIR filter is based on a tunable multi-wavelength laser and dispersion compensation fiber (DCF) while the IIR filter is simply based on an optical loop.

Impact of molecular solvophobicity vs. solvophilicity on device performances of dimeric perylene diimide based solution-processed non-fullerene organic solar cells.

Because of their outstanding molecular optoelectronic properties, perylene diimides (PDIs) are promising alternatives to the commonly used PCBM. However, the overly strong aggregation ability, poor solution-processability and compatibility of PDIs severely limit their photovoltaic applications. We turned to borrowing the amphiphile concept to improve these supramolecular properties.

Comparison analysis of optical frequency comb generation with nonlinear effects in highly nonlinear fibers.

We compare several schemes for broadband optical frequency comb (OFC) generation based on several nonlinear effects in highly nonlinear fiber (HNLF). Cascaded four wave mixing (CFWM) and self-phase modulation (SPM) processes in HNLF are proved to be effective ways for spectrum broadening. We investigate some parameters affecting the performance of the output OFC in detail.

In-line polarization-dependent microfiber interferometers and their applications in UWB signal generation.

A novel in-line polarization-dependent microfiber interferometer (PD-MFI) is proposed and experimentally demonstrated, which is tapered from a commercial polarization-maintaining fiber. Different from conventional MFIs, the transmission spectra of such MFIs are highly polarization-dependent, due to the mode-sensitive birefringence. The experimental results agree well with the theoretical predictions.

Compact, flexible and versatile photonic differentiator using silicon Mach-Zehnder interferometers.

We propose and experimentally demonstrate the flexibility and versatility of photonic differentiators using a silicon-based Mach-Zehnder Interferometer (MZI) structure. Two differentiation schemes are investigated. In the first scheme, we demonstrate high-order photonic field differentiators using on-chip cascaded MZIs, including first-, second-, and third-order differentiators.

All-optical computation system for solving differential equations based on optical intensity differentiator.

We propose and experimentally demonstrate an all-optical differentiator-based computation system used for solving constant-coefficient first-order linear ordinary differential equations. It consists of an all-optical intensity differentiator and a wavelength converter, both based on a semiconductor optical amplifier (SOA) and an optical filter (OF). The equation is solved for various values of the constant-coefficient and two considered input waveforms, namely, super-Gaussian and Gaussian signals.

Single SOA based simultaneous amplitude regeneration for WDM-PDM RZ-PSK signals.

We propose and demonstrate all-optical amplitude regeneration for the wavelength division multiplexing and polarization division multiplexing (WDM-PDM) return-to-zero phase shift keying (RZ-PSK) signals using a single semiconductor optical amplifier (SOA) and subsequent filtering. The regeneration is based on the cross phase modulation (XPM) effect in the saturated SOA and the subsequent narrow filtering. The spectrum of the distorted signal can be broadened due to the phase modulation induced by the synchronous optical clock signal.

Phase regeneration of phase-shift keying signals in highly nonlinear hybrid plasmonic waveguides.

Phase regeneration of phase-shift keying signals is theoretically proposed, we believe for the first time, based on the efficient optical parametric amplification (OPA) process in a highly nonlinear symmetric hybrid plasmonic waveguide. This optimized stacked waveguide with nonlinear organic materials has a relatively low loss of about 0.005 dB/μm and an effective nonlinear OPA coupling coefficient up to 60 ps/m/W(1/2).

High-order photonic differentiator employing on-chip cascaded microring resonators.

We propose and experimentally demonstrate a high-order photonic differentiator using on-chip complementary metal oxide semiconductor-compatible cascaded microring resonators, including first-, second-, and third-order differentiators. All the microring resonator units have a radius of 150 μm and a free spectral range of 80 GHz. The microring resonator can implement the first-order derivative of the optical field near its critical coupling region.

Slow light in an alternative row of ellipse-hole photonic crystal waveguide.

High normalized delay-bandwidth product (NDBP) and wideband slow light are achieved in an alternative row of ellipse-hole photonic crystal waveguide. Two different criteria of flat ratio are adopted. Under a constant group index criterion, a high NDBP of 0.

Cardioprotective effect of erythropoietin on sepsis-induced myocardial injury in rats.

Background: Sepsis-induced myocardial injury is one of the major predictors of morbidity and mortality of sepsis. The cytoprotective function of erythropoietin (EPO) has been discovered and extensively studied. However, the cardioprotective effects of EPO on sepsis-induced myocardial injury in the rat sepsis model has not been reported.

Nanohole induced microfiber Bragg gratings.

We demonstrate the fabrication of high-index-contrast microfiber Bragg gratings (MFBGs) using phase-mask technique under seconds' femtosecond laser ablation to drill periodic nanoholes in microfibers and study the aging properties of the gratings at room temperature. These sub-micrometer-diameter holes, benefited from the resolution of femtosecond laser micromachining beyond-diffraction limit, results in an effective negative refractive index change Δn ~-10(-3). Transmission dips over -23 dB are achieved for the gratings with excellent Gaussian apodization and 3-dB reflection bandwidths up to 1.

Simultaneous RZ-OOK to NRZ-OOK and RZ-DPSK to NRZ-DPSK format conversion in a silicon microring resonator.

Simultaneous RZ-OOK to NRZ-OOK and RZ-DPSK to NRZ-DPSK modulation format conversion in a single silicon microring resonator with free spectral range equal to twice the signal bit rate is experimentally demonstrated for the first time at 41.6 Gb/s. By utilizing an optimized custom-made microring resonator with high coupling coefficient followed by an optical bandpass filter with appropriate bandwidth, good conversion performances for both modulation formats are achieved according to the converted signals eye diagrams and bit-error-rate measurements.

Photonic generation of ultra-wideband doublet pulse using a semiconductor-optical-amplifier based polarization-diversified loop.

We propose and demonstrate a novel scheme of ultra-wideband (UWB) doublet pulse generation using a semiconductor optical amplifier (SOA) based polarization-diversified loop (PDL) without any assistant light. In our scheme, the incoming gaussian pulse is split into two parts by the PDL, and each of them is intensity modulated by the other due to cross-gain modulation (XGM) in the SOA. Then, both parts are recombined with incoherent summation to form a UWB doublet pulse.

[Effects of fluid resuscitation on myocardial injury in patients with severe sepsis and septic shock].

Objective: To observe the influence of fluid resuscitation on patients suffered from myocardial injury with severe sepsis and septic shock, and to evaluate the markers of myocardial injury during fluid resuscitation.

Methods: Acute physiology and chronic health evaluation II (APACHE II) score of 78 patients with severe sepsis and septic shock induced by combined injuries was 18-35. Serum cardiac troponin I (cTnI), N-terminal-ventricular natriuretic peptide precursor (NT-proBNP) and the hemodynamic parameters were recorded before, 3 days, and 5 days after treatment, and correlative analysis was conducted.

Dual-band optical filter based on a single microdisk resonator.

We propose and experimentally demonstrate a dual-band optical filter based on a single microdisk resonator. An analytical model is built based on the transfer matrix method and is applied to simulate the properties of such a device. Competition and interference of the dual modes in the resonator lead to dual-band filtering with high isolation.

All-optical clock recovery from 40 Gbit/s RZ signal based on microring resonators.

A scheme for high-speed clock recovery from return-to-zero (RZ) signal with microring resonators is presented. By using a silicon microring resonator (MRR) for clock extraction and a 3-order nonlinear series-coupled microring resonator (SCMR) for amplitude equalization, clock pulses with amplitude modulation less than 1 dB can be obtained. The proposed scheme is also designed and numerically studied by 3D full vectorial film mode matching method (FMM) and coupled mode theory (CMT).

All-optical parallel NRZ-DPSK to RZ-DPSK format conversion at 40 Gb/s based on XPM effect in a single SOA.

We propose and demonstrate multi-channel parallel format conversions from the non return-to-zero differential phase shift keying (NRZ-DPSK) to the return-to-zero DPSK (RZ-DPSK) using a single semiconductor optical amplifier (SOA). The simultaneous conversions are based on the cross phase modulation (XPM) effect, which is induced by a synchronous optical clock signal with high input power. The XPM adds an identical phase shift onto every input bit, resulting in the phase difference unchanged.