Experimental Investigation of All-Optical NRZ-DPSK to RZ-DPSK Format Conversion Based on TOAD

We propose and experimentally demonstrate a novel all-optical non-return-to-zero differential-phase-shift-keying （NRZ-DPSK） to return-to-zero differentiM-phase-shift-keying （RZ-DPSK） format conversion scheme. This scheme is based on the terahertz optical asymmetric demultiplexer （TOAD）. A 10 Gb/s converted RZ-DPSK signal is obtained with a wide duty cycle tuning range from 16% to 66%. For all converted RZ-DPSK signals, the receiver sensitivities at BER of 10-9 are 0.4 to 1.7dB higher compared with the original NRZ-DPSK signal. The clear and open eye diagrams are presented to demonstrate the high quality format conversion performance. Moreover, the optical spectra show that this conversion is in a wavelength-preserving operation.

All-optical two-channel polarization-multiplexing format conversion from QPSK to BPSK signals in a silicon waveguide

All-optical two-channel format conversion is proposed and experimentally demonstrated from a 40 Gbit/s polarization multiplexing(Pol-MUX) non-return-to-zero quadrature phase-shift keying(QPSK) signal to Pol-MUX binary phase-shift keying(BPSK) signals by using phase-doubled four-wave mixing effects with two polarization-angled pumps in a silicon waveguide. The eye diagrams and constellation diagrams of the original QPSK sequences and the converted BPSK sequences of each channel are clearly observed on the two polarization states. Moreover,the bit error rates(BERs) of the two converted idlers are measured. The power penalties of all these converted BPSK sequences on both X and Y polarization states are less than 3.4 dB at a BER of 3.8 × 10^(-3).

Theoretical study of all-optical RZ-OOK to NRZ-OOK format conversion in uniform FBG for mixed line-rate DWDM systems

In this work we study all-optical multi-channel return-to-zero （RZ）-on-off keying （OOK） to nonreturn-to-zero （NRZ）-OOK format conversion in single uniform fiber Bragg grating （FBG） for mixed line-rate dense wave- length-division multiplexing systems using mathematical simulations. Forty and 20 Gbit/s RZ-OOK signals with 33% and 50% duty cycles are converted to NRZ-OOK signals in single uniform FBG with 21~ reflectivity. Impact of amplitude noise from FBG contrast profile on modulation format conversion efficiency is also studied.

All-optical clock recovery from 10-Gb/s NRZ data and NRZ to RZ format conversion

A non-return-to-zero （NRZ） to pseudo-return-to-zero （PRZ） converter consisting of a semiconductor optical amplifier （SOA） and an arrayed waveguide grating （AWG） is proposed, by which the enhancement of clock frequency component and clock-to-data suppression ratio of the XRZ data are evidently achieved. All- optical clock recovery from XRZ data at 10 Gb/s is successfully demonstrated with the proposed XRZ-to- PRZ converter and a mode-locked SOA fiber laser. Furthermore, XRZ-to-RZ format conversion of 10 Gb/s is realized bv using the recovered clock as the control light of terahertz optical asymmetric demultiplexer （TOAD）, which further proves that the proposed clock recovery scheme is applicable.

Mutual optical format conversion between on-of keying and binary phase-shift keying based on stimulated brillouin scattering

We propose and experimentally demonstrate mutual optical format conversion between signals characterized as 10-Gb/s nonreturn-to-zero on-of-keying(NRZ-OOK) and NRZ binary phase-shift keying(BPSK) types. The conversion is based on stimulated Brillouin scattering(SBS) in a single-mode optical fber. An OOK signal is converted into a BPSK signal through optical carrier absorption, for which a SBS loss of 30 MHz is used in long-haul transmission. The converted BPSK signal is reverted to an OOK signal with a corresponding SBS gain of 30 MHz for direct detection. The proposed OOK-to-BPSK and BPSK-to-OOK format conversions can be implemented in transmitter and receiver nodes by using a laser source as the Brillouin pump.

All-optical format conversion from RZ-QPSK to NRZ-QPSK

We proposed and demonstrated an all-optical format conversion fi：om return-to-zero quadrature phase shift keying （RZ-QPSK） to non-return-to-zero QPSK （NRZ-QPSK） at 40 Gb/s using a half bit delay inter- ferometer （DI）. Due to the constructive interference in the DI, the format conversion was achieved with the phase information preserved. Q penalty for the format conversion was less than 1.8 dB for I and Q data.

Formation of Methane and Ethylene in Methanol Conversion over HZSM-5 Catalyst

Primary formation of methane and secondary formation of ethylene in methanol conversion are evidenced by temperature-programmed-surface- reaction of adsorbed methanol on HZSM-5 catalyst.A reaction mechanism accounts for the observed results is described.

Densely packed ultrafine SnO_(2) nanoparticles grown on carbon cloth for selective CO_(2) reduction to formate

Electrochemical reduction of CO_(2) to fuels and chemicals is a viable strategy for CO_(2) utilization and renewable energy storage.Developing free-standing electrodes from robust and scalable electrocatalysts becomes highly desirable.Here,dense SnO_(2) nanoparticles are uniformly grown on three-dimensional(3D)fiber network of carbon cloth(CC)by a facile dip-coating and calcination method.Importantly,Zn modification strategy is employed to restrain the growth of long-range order of SnO_(2) lattices and to produce rich grain boundaries.The hybrid architecture can act as a flexible electrode for CO_(2)-to-formate conversion,which delivers a high partial current of 18.8 m A cm-2 with a formate selectivity of 80%at a moderate cathodic potential of-0.947 V vs.RHE.The electrode exhibits remarkable stability over a 16 h continuous operation.The superior performance is attributed to the synergistic effect of ultrafine SnO_(2) nanoparticles with abundant active sites and 3D fiber network of the electrode for efficient mass transport and electron transfer.The sizeable electrodes hold promise for industrial applications.

Digitization and DICOM Standardization of X-ray Image Signal

Picture archiving and communication system (PACS) has played an important role in hospital and developed rapidly in recent years. It is an important part of PACS architecture that X-ray video output connects with PACS. In this paper, a method to digitize the video signals of X-ray facility is introduced. By means of the video capture card, we can acquire digital medical images from X-ray facility. The American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) developed a standard for Digital Imaging and Communications in Medicine (DICOM), this DICOM standard introduces a rule of medical image conversion from conventional format to DICOM one. According to abovementioned standard, X-ray video signals can be connected to PACS easily. This project has been applied in some hospitals successfully and there is satisfied result. Key words image acquisition - image compression - format conversion - DICOM - PACS CLC number TP 391 Foundation item: Supported by the Enterprise Innovation Foundation of Wuhan (WS(2001)14)Biography: ZHOU Li (1977-), male, Master, research direction: microelectronics and solid electronics.

Linear optical signal processing with optical filters： a tutorial

An effective theoretical analysis method is presented to analyze different linear optical signal processing functions with optical fikers reported in literatures. For different applications, the optical filters are supposed to operate on the analog or digital part of the signal separately, namely analog spectrum conversion and digital spectrum conversion. For instance, the return-to-zero （RZ） to non-return-to-zero （NRZ） format conversion for intensity or phase modulated signals are based on the analog spectrum conversion process, while the （N）RZ to （N）RZ phase-shift-keying （PSK） format conversion, logic NOT gate and clock recovery for RZ signals are based on the digital spectrum conversion process. Theoretical analyses with the help of numerical simulation are used to verify the reported experimental results, and all the experimental results can be effectively analyzed with this analytical model. The effect of the transmission spectrum of the filter on the performance of the converted signal is investigated. The most important factor is that the theoretical analysis provides an effective way to optimize the optical filter for different optical signal processing functions.