Predistortion of high speed optical OFDM signal for aliasing-free receiving in multiple low-bandwidth receiver system

<正>A cost-effective method of multi-receiver optical orthogonal frequency-division multiplexing(OOFDM) system is proposed to reduce the requirement for the speed of the receiver and the size of fast Fourier transform(FFT).The sampling rate of analog-to-digital converters(ADCs) can be reduced to 1/N of the original signal bandwidth in an N-receiver system.Aided by signal predistortion at the transmitter, aliasing-free signal can be retrieved independently and directly at the low speed receivers.A back-to-back experimental result is given for a two-receiver system.The effect of the electrical filters added before the ADC is studied and the analysis for filters optimization is given.     

All-Optical AND Logic Gate without Additional Input Beam by Utilizing Cross Polarization Modulation Effect

A novel design of all-optical AND gate is proposed by using cross polarization modulation effect in a semiconductor optical amplifier. In this scheme, an additional continuous-wave beam is not required as that in traditional scheme. AND output is obtained on either of two input signal wavelengths. The AND scheme is numerically simulated and experimentally demonstrated at a bit rate of 10 Gb/s successfully.     

Heterodyne direct-detection OOFDM system with low sampling rate

A method of multi-channel receiving for high bit rate heterodyne direct-detection optical orthogonal frequency-division-multiplexing （OOFDM） system is proposed to reduce the sampling rate demand of analog-to-digital converter （ADC）. The sampling rate of ADCs can be reduced to 1/N that of the original signal bandwidth in an N-channel receiving system. Aided by a succeeding digital signal processing （DSP） at the receiver, aliasing free signal can be recovered. A back-to-back experimental result is given for a 4-channel system, based on which, a down conversion process for heterodyne can be reduced. The signal rebuilding algorithm is given and analyzed in its complexity and noise tolerance.     

A Step—by—Step Tunable Compound External Cavity Semiconductor Laser with Two—Side Feedback Coupling

A kind of compound external cavity semiconductor lasers(CECSL) is presented,by which laser with a discretely tunable wavelength can be obtained to meet the potential demands of the wavelength division multiplexing system.By the introduction of two-side feedback coupling in the CECSL,the CeCSL can operate more efficiently,and its side-mode suppression ratio is high up to 50dB.     

Waveguide structure optimization of arrayed waveguide gratings concatenation in cascaded optical add/drop multiplexers

The dimensions of input waveguide and output waveguide of arrayed waveguide gratings (AWGs) determine the crosstalk, insertion loss and 1-dB bandwidth. In cascaded optical add/drop multiplexers (OADMs), the value of these parameters will largely affect the power penalty of system. The power penalty of cascaded OADMs is calculated with different waveguide dimensions of AWGs in this paper. Considering of wavelength misalignment, an optimization design of AWGs is obtained.     

可调谐单模窄线宽外腔半导体激光器

可谐谐单模窄线宽外腔半导体激光器具有光谱纯度高，波长覆盖范围广（０．６－３５μｍ）、结构紧凑、效率高，寿命长，成本低，可靠性高，使用方便等突出优点，９０年代以来已在新兴的光纤通信，光学元件测试，计量检测传感、高分辨率光谱分析、生物医学等领域推广应用，本文对外腔半导体激光器的工作原理，结构性能，发展历史及应用前景作了简要的介绍。     

两套小冰麦异附加系的建立

本文报道了把天兰冰草(Agropyrn intermedium)的两个染色体组的14对染色体分别加入小麦,建立起两套小冰麦异附加系列的程序和方法,并对所建立的14种异附加系的表型特征进行了观察分析,查明有些小冰麦异附加系中的冰草染色体上携带有抗锈病基因。此外,本文还讨论了与一些农艺性状有关的基因在不同冰草染色体上的分布。     

Tunable multi-wavelength microwave photonic filter based on the superposition of transfer functions

A microwave photonic filter （MPF） with reconfigurability and tunability resulting from the superposition of the transfer functions is proposed. Based on the Vernier effect between the optical frequency combs and the periodic optical filters, each comb line can be mapped into a sub-filter in the electronic field. The sub-filters are superposed to obtain the total transfer function of the MPF. By manipulating a few comb lines, we can reconfigure the passband shape, tune the bandwidth, and adjust the center frequency independently. Experiments verify that the bandwidth can be tuned from 224.8 to 674.3 MHz, and that the center frequency ranges from 1 to 4 CHz.     

IM分担一个或两个小函数的亚纯函数的唯一性

In this paper, the uniqueness problems of two meromorphic functions sharing one or two small functions IM are studied. By imposing certain conditions on the counting functions of four or three other small functions and constructing auxiliary function, some general uniqueness results are obtained.     

Amplitude Regenerative Characteristics of RZ-DPSK Wavelength Converter Based on Four-Wave Mixing in SOA

We investigate the phase-preserving amplitude regenerative characteristics of the return-to-zero （RZ） differential- phase-shift-keying （DPSK） wavelength conversion based on four-wave m/xing （FWM） in a semiconductor optical amplifier （SOA）. The Q-factor and the optical signal-to-noise ratio （OSNR） before and after conversion are experimentally obtained and analysed in different input noise power levels. In both the continuous-wave and synchronous clock pumping cases, we find that there is amplitude clamping in the FWM conversion due to the gain saturation of SOA, which can suppress the amplitude fluctuation of the converted DPSK signal before and after demodulation. We have achieved 2-dB Q penalty improvement in our experiment demonstration of lOGbit/s RZ-DPSK signal with OSNR lower than 19dB.