分别用980 nm和830 nm的半导体激光器作为泵浦源激发铋/铒共掺光纤，采用前向和背向泵浦方式分析放大的自发辐射谱特性.实验结果表明：随着泵浦功率的增大，荧光强度显著增强.利用980 nm半导体激光器，采用前向泵浦方式可激发以1 142 nm和1 536 nm为中心的两个辐射带，以1 142 nm为最高辐射峰的3 dB带宽是141 nm，以1 536 nm为最高辐射峰的3 dB带宽是29 nm.利用830 nm半导体激光器，采用前向泵浦方式可激发以1 421 nm为中心的荧光谱，3 dB带宽是447 nm.980 nm和830 nm激光器分别前向泵浦铋/铒共掺光纤时，随着光纤长度的增加，荧光先增强后减弱；分别背向泵浦铋/铒共掺光纤时，随着光纤长度的增加，荧光强度先逐渐增强后保持稳定.在25~80℃的温度范围内，铋/铒共掺光纤的荧光强度几乎不受温度的影响.使用980 nm和830 nm泵浦源同时激发铋/铒共掺光纤，结果表明铋/铒共掺光纤的发光中心具有相对独立性，发光范围存在部分重叠.

To evaluate the light field display system with a liquid crystal display (LCD) and a holographic functional screen (HFS), the voxel theory based on the ray tracing is used. By analyzing the voxels defined by the cases of corresponding pixels overlapping completely and partially in the image space, the resolution characteristics of the system are discussed. The theoretical model is verified in the reconstruction experiment of a resolution target and compared with the calculation result of the presented system. Finally, we give an optimization method for the display image quality.

We propose a novel scheme for synchronous optical sampling based on multicast parametric process. The linearly chirped and time-broadened pulses are utilized to replace the traditional mode-locked sampling pulses. An optical sampling rate of 80 Gbit/s is realized by using only one sampling source with repetition rate of 10 GHz.

提出一种稳定的波长间隔可调谐的双波长单纵模环形光纤激光器.在复合环形谐振腔中，采用由数字微镜装置（DMD）滤波器和两个不同长度的次级环形谐振腔组成的多重滤波的方式来选择激光器的工作模式.其中，DMD滤波器可以从掺铒光纤的自发增益谱中任意选择两个波长并将它们耦合进光路中；次级环形谐振腔作为模式滤波器，可以保证激光器输出单纵模激射；利用非线性光子晶体光纤（HN-PCF）的四波混频（FWM）效应，使激光器输出均衡平稳的双波长激射.在室温条件下，不用移动实验装置中的任何器件，通过将位置不同的光栅映射在DMD滤波器上来实现双波长间隔可调谐，调谐范围为0.165 nm到1.08 nm，调谐步长为0.055 nm.

针对伪毫米波超宽带信号脉冲宽度窄且信号强度低而不易探测的特点, 本文提出了两种光学辅助包络探测方案.将伪毫米波超宽带信号调制到光载波上, 利用光纤布喇格光栅带通滤波器滤出调制器输出的第一边带信号, 通过光电探测器和低通滤波器便可以得到用于判决的伪毫米波超宽带信号的包络信息.数学推导和仿真分析了分别采用相位调制器和强度调制器对输出包络信号振幅的影响. 研究结果表明：强度调制器需要偏置控制电路来稳定偏置点的位置, 当强度调制器工作在最小传输点时, 得到的包络信号幅值最大;相位调制器无需偏置控制电路, 其输出信号包络的幅值等于使用强度调制器的系统可得到的最大值;使用相位调制器的系统较使用强制调制器的系统具有结构更简单和插入损耗更低的特点.

A new receiver is proposed, which uses the fiber optical parametric amplifier (FOPA) in optical code division multiple access (OCDMA) over free space optic (FSO) communication system. The noise tolerance as the performance index in this receiver is derived. The receiver can not only improve the noise tolerance but also change the pump data conveniently for adapting to the length variation of the coding sequence under a complex and fast-changing weather condition. The influence of different factors on the noise tolerance is analyzed, and a significant improvement of about 18.77 dB for the noise tolerance can be achieved when the pump power and the length of coding sequence are 5 W and 256, respectively.

We investigate the spectra of the gain and pump-to-signal relative intensity noise (RIN) transfer in silicon optical parametric amplifier (SOPA) with Raman effect, and draw a conclusion that Raman effect makes the spectra narrower from 260 nm to 180 nm. A maximum gain also appears at 1622 nm. Moreover, the effects of the related parameters in SOPA on the gain and the pump-to-signal RIN transfer characteristics are also discussed. The high gain (16 dB) and low pump-to-signal RIN transfer (7 dB) can be obtained by using the appropriate parameters of pump and silicon waveguide.

This paper proposes a kind of modulation architecture for wavelength-division-multiplexing passive optical network (WDMPON) employing optical differential quadrature phase shift keying (DQPSK) downstream signals and two different modulation formats of re-modulated upstream signals. At the optical line terminal (OLT), 10 Gbit/s signal is modulated with DQPSK. At the optical network unit (ONU), part of the downstream signal is re-modulated with on-off keying (OOK) or inverse-return-to-zero (IRZ). Simulation results show the impact on the system employing NRZ, RZ and carrier-suppressed return-to-zero (CSRZ). The analyses also reflect that the architecture can restrain chromatic dispersion and channel crosstalk, which makes it the best architecture of access network in the future.

We propose the single feeder fiber architecture for wavelength division multiplexing passive optical network (WDM-PON) based on directly modulated chirp managed laser (CML). The downlink (DL) signal output from the laser is converted to return-to-zero (RZ) differential phase shift signal using a pulse carver. The downstream signal is reused as a carrier for the upstream using intensity modulation technique. Simulation results show the error-free performance at symmetric data rate of 10 Gbit/s per channel with negligible power penalty and improved receiver sensitivity for the uplink (UL), over 25 km standard single-mode fiber (SSMF). A low-cost and reduced circuitry network design is implemented on a single feeder fiber with the elimination of differential encoder and one external modulator.

The performance of colorless wavelength-division multiplexed passive optical network (WDM-PON) systems suffers from the transmission impairments mainly due to Rayleigh backscattering (RB). In this paper, we propose and demonstrate a single fiber colorless WDM-PON which enhances the tolerance to RB induced noise. The high extinction ratio in both return-to-zero (RZ)-shaped differential phase shift keying (DPSK) downstream (DS) data signal and intensity-remodulated upstream (US) data signal helps to improve the tolerance to RB induced noise. Simulation results show that downstream and upstream signals can achieve error-free performance at 10 Gbit/s with negligible penalty and improve the tolerance to RB induced noise over 25 km standard single-mode fiber.