光纤中线性偏振模式的选择是影响模分复用系统传输质量的关键因素.为此首先设计了基于模分与波分混合复用的直接检测光纤传输系统;其次,基于光纤中线性偏振模式理论,利用Optisystem15.0软件仿真研究LP01、LP11、LP02、LP12、LP215个模式在该光纤传输系统中的传输特性;然后,将LP01、LP11、LP02、LP12四模式复用,仿真得到了折射率渐变多模光纤纤芯半径在19～25μm范围内变化时,各通道Q因子均在7以上的纤芯半径最优化值为21～22μm,且此最优值不随传输距离而变化;最后,在八通道混合复用系统中采用直接检测方式实现了误码率在10-9以下的2.0 km短距离传输.

Cognitive radio is a kind of intelligent reasoning learning communication system, and fuzzy Q learning method is introduced to realize the cognitive radio spectrum allocation intelligent learning process. Cognitive users adjust the fuzzy inference system through online Q learning, obtain the optimal fuzzy rules of spectrum allocation and realize the adaptive spectrum allocation scheme. The fuzzy Q spectrum allocation algorithm is compared with non intelligent learning algorithm (fuzzy spectrum allocation algorithm and random distribution algorithm). And the simulation results show that this algorithm improves the system bandwidth income and reduces the system conflict rate.

Characteristics of time domain on low-repetition-rate pulse amplification was analyzed,the time domain theory of laser pulse amplification was obtained.The different low-repetition-rate pulse amplification was studied by using the time domain theory,and the amplification project was presented when the optimum conversion efficiency was gained,the time domain theory has been tested in reported experiments adequately,the improved project is proposed for the part of experiments.

In view of the lack of theoretical research of multi-pass pulse amplification system, established multi-pass pulsed amplification theoretical model based on the basic principle of multi-pass amplification and the rate equation of pulse laser multi-pass amplification, and studied the transmission characteristics of pulse in multi-pass amplifying system. Through the simulation research of the theoretical model, obtained the relation of output power and pump power and the relation of output single pulse energy and pulse repetition frequency.

In order to improve the optical-optical conversion efficiency of the pulse amplification system model,the output characteristics of the dual-pass pulse amplification were studied by means of modeling and simulation. From the transmission characteristics,the relationship between output power and pump power,the relationship between output single pulse energy and pulse repetition frequency,and the relationship between conversion efficiency and repetition rate were obtained. The optical to optical conversion efficiency was 29. 1% when the repetition frequency was 40kHz. Therefore,this dual-pass pulse amplification model improved the efficiency of energy conversion.

This paper fouces on the spectrum handoff in cognitive radio which secondary users(SU) usually use the overlay spectrum acess scenario. We use the fuzzy logic and pridect a reserved channel table, when the spectrum handoff occur, SU can choose the available spetrum access quickly. Because of primary users(PU) appear uncertainty, the correctness of backup channel can not ensure. To aim at this problem, we decrease the error of table via detecting spectrum occupation rate real-time to update backup channel table in this paper. Simulation result show that our proposed scheme can reduce the handoff delay, increase the correctness of reserved channel table and improve the effective data rate.

双轨制,即对硕士研究生实行中期分流,形成应用型硕士与研究型硕士两套培养方案。文章通过对计算机应用技术专业研究生的培养模式进行改革,对该专业的研究生实行应用型硕士与研究型硕士两套培养方案,在研究生培养中遵循因材施教原则,达到全面提高研究生培养质量的目的。

Effects of the intra-cavity losses on coherent combining in a Mach-Zehnder Erbium-doped fiber laser cavity were experimentally demonstrated. A FBG with 4% reflectivity replaced the cleaved facet with 4% Fresnel reflection. This output port can emit the maximal coherent output power only when the outputs of one-arm pumped laser are balanceable. The maximal coherent output can emit from the FBG and is approximately four times the single output of the one-arm pumped laser. When the cavity losses are decreased, the unbalance between the two outputs is aggravated. The maximal coherent output emits from the port with the isolator, and the coherent output will not reach four times the single output of the one-arm pumped laser from the isolator. But it can exceed the sum of all the outputs of the one-arm pumped lasers at the same pump level.

Based on the principle of double-pass amplification,establishes a double-pass pulse amplifier experimental model.From pulse laser double-pass amplification rate equations,establishes a double-pass pulse amplification theoretical model,studies the transmission characteristics of the pulse in the double-pass amplification system,and obtains the relations between ASE(amplified spontaneous emission)and pump energy,the relations between ASE and the repeat frequency of the signal light,as well as the relations between the gain and the output signal power.Finally,the quality factor Q of the system is derived through calculating.

Orientation-curricula system mainly based on professional training,with its focus on the development of students' abilities,is social needs oriented.Based on the communication engineering status quo and the interrelationship of the teaching content it aims to integrate the content concerning the development of abilities and construct the orientation-curricular system for professional capacity building.Through the training under such a system students can be practically competent with a solid foundation in professional knowledge in certain field of engineering.

Because of the necessity and importance of the study on optical fiber grating reconstruction,introduces the fiber Bragg grating(FBG) and studies the grating basic structure factors from the modulation principle about fiber Bragg grating's refractive index.Then deduces and expounds the transfer matrix method of FBG for uniformly modulated grating.Meanwhile,analyzes in detail the principle and the steps of layer peeling(LP) algorithm.Finally,based on LP algorithm,makes the related simulation and realizes the reconstructing of FBG,and shortens the group delay of the grating's reconstruction.

Based on the all-optical pulse Yb-doped double-clad amplifier modeling,studies the dynamic transmission characteristics of nanosecond pulses.Without considering the input signal,the upper-level population of ytterbium-doped double-clad fiber by forward-pumped distributes the characteristics of high intermediate and low at two ends.Considering the continuous signal input and the existence of weak feedback in amplifier,the backward amplified signals caused by the weak feedback consumes more number of upper-level particles as the pump power is higher.When the fiber length increases,a positive signal output power reduces.

在通信英语教学中,弹性扩充教学内容,以教师引导为主线,学生自主探究为中心,师生共同促进为目的,从而达到教学相长、培养学生的"自学能力、创新能力、实践能力和就业能力"的培养目标。

Based on the principle of self-organization in Mach-Zehnder erbium-doped fiber laser cavity,charateristics of leak power are theoretically and experimentally demonstrated.One 3dB fiber loop mirror and a fiber Bragg grating with 4.5% reflectivity are used as cavity mirrors.A high coherent combining efficiency of 93.5% was obtained.Research on characteristics of leak power opens out self-organization mechanism in Mach-Zehnder compound cavity.Many applications to coherent combining high power lasers are expected.