无源光网络中突发光功率计校准方法的研究

介绍了一种利用连续光功率计和示波器进行突发光功率计校准的方法,设计制作了稳定度为±0.01dB/15 min的脉冲光源,通过将脉冲功率的直接测量转换为平均功率的间接测量,实现了突发光功率量值的有效溯源。给出了不确定度评定方法,在0.1 dB分辨力条件下测量不确定度达到0.2dB(k=2)。该方法和装置被广泛用于无源光网络突发光功率计的校准,保证了实际工程中突发光功率测量的准确性。     

抑制噪声的宽带碲基掺铒光纤放大器性能分析

设计了一个带光隔离器的复合型宽带碲基掺铒光纤放大器（EDTFA）,通过对该结构模型下的速率方程和光功率传输方程组的数值模拟,理论研究了EDTFA在插入光隔离器后的性能变化。研究表明,通过插入光隔离器抑制反向传输的放大自发辐射（ASE）噪声,可以有效地改善宽带EDTFA的信号增益和噪声特性。在光纤激活长度240cm、铒掺杂浓度2000ppm和前向泵浦功率200mW下,光隔离器插入在最佳位置处时,1540nm～1600nm波段内16路信道小信号增益分别提高了0.8dB～5．9dB,噪声系数降低了0.2dB～2．2dB。研究结果对于新型宽带EDTFA应用于WDM通信系统中具有理论指导意义。     

分布式光纤温度传感的拉曼散射理论分析

本文比较系统地分析了光纤中泵浦光向拉曼斯托克斯光转换的过程,同时讨论了斯托克斯光随注入泵浦光变化的情形,引入了泵浦阈值功率的概念,为分布式光纤温度传感器系统打下了理论基础。     

一种新颖的偏振不敏感的阵列波导光栅

提出了一种新颖偏振不敏感的阵列波导光栅(AWG)。器件的输入端增加了一个全光学偏振自动控制器(AOPSC),可将注入AWG的随机偏振的输入光转换为与AWG中TE0模偏振方向相同且功率损耗很小的线偏振光。AWG结构设计采用非对称的平面波导,包层与波导芯层的相对折射率差为0.7%,波导芯层的宽厚比要高,可以消除TE与TM模的简并,使波导中只能激励TE0模,而使TM0模截止。这种AWG结构完全消除了不同偏振态信号光对AWG工作性能的影响,从而使器件对偏振不敏感。设计的8×0.8nm器件整体尺寸为2cm×1cm,串扰优于-30dB,最大插入损耗为4.2dB。     

一种新型的微机械可变式光衰减器

介绍了一种新型的连续可变式微机械单模光衰减器的设计与制作。该光衰减器采用电磁型微驱动器驱动一个铁镍合金衰减片，使其插入两根准直的单模光纤的间隙中，依靠精密地调节衰减片切入光路中的位置而实现对传输光功率的连续衰减。采用硅微细加工技术成功地制作出了这种光衰减器，并对微驱动器的性能进行了理论分析。测试结果表明，当传输的光波长为1550nm时，该衰减器的平均插入损耗为2.5dB，衰减范围为2.5-45dB，回波损耗为40dB。     

有理数谐波锁模SOA光纤环形激光器数值研究

采用自再现理论,对工作在有理数谐波锁模时的半导体光放大器(SOA)光纤环形激光器进行了研究.为了获得振幅均衡的有理数谐波锁模脉冲,必须在原有的实验装置中添加一个掺铒光纤放大器(EDFA)以提高注入调制光信号功率.数值结果表明,调制SOA的偏置电流和注入调制光信号功率对有理数谐波锁模脉冲的振幅均衡度都存在较大影响.合理选择调制SOA的偏置电流和注入调制光信号功率,可获得2～5阶振幅均衡的有理数谐波锁模脉冲序列.     

钢球表面缺陷检测用双光路光源稳定控制技术研究

半导体激光器作为光源产生器件进行钢球表面缺陷检测时，由于其自身的材质和结构，输出光功率受注入电流和温度变化的影响很大，光源很容易产生波动，这对检测结果产生了较大的干扰，影响钢球表面缺陷检测的准确率。本文设计了一种用于钢球表面质量检测的小功率半导体激光器功率稳定系统。通过上位机对单片机烧录程序实现对半导体激光器发光功率的自动控制，系统设计有光功率反馈模块、温度控制模块和光隔离模块，可以有效的消除电流浪涌现象、温度变化和反射光干扰等因素对激光器输出功率的影响，保证激光器发出恒定功率的稳定光。最后对1310 nm的激光器进行了测试，该系统将光功率的不稳定度从9.37%降低到1.42%，为后续的钢球表面缺陷检测奠定了良好的基础。     

10Gbit/s色散补偿系统中自相位调制效应的研究

首先讨论了单模光纤中自相位调制对系统色散的影响。数值计算和实验结果表明。增加入纤功率能在一定程度上抑制色散效应 ,当入纤功率为 1 5dBm时 ,对于 4 0 .0km的单模光纤 ,自相位调制效应和色散恰好抵消 ,功率代价接近为零。然后比较了前、后置色散补偿系统的性能。理论分析和实验表明 ,在入纤光功率较大的情况下 ,采取前置、完全色散补偿系统具有较低的误码率。前置补偿最佳入纤功率比后置补偿最佳入纤功率高约 1 0 .0dB。这表明 ,采取前置、完全色散补偿 ,系统具有较长的中继距离和较高的接收端光信噪比 ,对 (1 6 0× 1 0Gbit/s)DWDM系统 30 0 0km超长距离传输中光放大和色散补偿问题的整体优化具有重要现实意义。     

在DCF光纤中放大的背向自发拉曼散射的增益特性

光脉冲沿色散补偿光纤（DCF）传输会产生背向自发拉曼散射,当入纤激光功率大于阈值时,出现放大的背向自发拉曼散射现象。实验发现,反斯托克斯（ASR）和斯托克斯（SR）自身脉冲光纤拉曼放大的阈值泵浦峰值脉冲功率是18．2W和14．5W．当入纤激光功率为52W时,背向SR和ASR散射的增益分别为12dB和7dB。放大的反斯托克斯和斯托克斯背向自发拉曼散射时域曲线上的阈值时间位置随激发功率的增大而前移并具有规律性。     

0.18μm CMOS 2.5Gb/s光接收机跨阻前置放大器的设计

给出了一种利用TSMC 0.18μm CMOS工艺实现的2.5 Gb/s跨阻前置放大器.此跨阻放大器的增益为66.3 dBΩ,3 dB带宽为2.18 GHz,等效输入电流噪声为112.54 nA.在标准的1.8 V电源电压下,功耗为7.74 mW.输入光功率为-10 dBm时,PCML单端输出信号电压摆幅为165 mVp-p.模拟结果表明该电路可以工作在2.5 Gb/s速率上.     

Optical characteristics of a refractive optical attenuator with respect to the wedge angles of a silicon optical leaker

We design, fabricate, and characterize the micromachined refractive variable optical attenuator (VOA) with a wedge-shaped silicon optical leaker (SOL). The vertical structures of the VOA device can be simply fabricated by deep reactive ion etching with no sidewall metallization, and the 8 degrees angled fibers are employed for a high return loss even in air-ambient conditions. The SOL successively transmits and refracts part of the incident light far outside the acceptance angle of the output fiber, showing an effective optical attenuation. The fabricated VOA gives high optical performances, such as a response time of 6 ms, a return loss of 39 dB, an insertion loss of 0.6 dB, an attenuation range of 43 dB, and a polarization-dependent loss (PDL) of a 10% attenuation level, including a wavelength-dependent loss. The optical characteristics of the VOA are also theoretically investigated with respect to the wedge angles of the SOL. The experimental characteristics are in good agreement with the theoretical values calculated, considering light scattered from the endface of an optical fiber and sidewall of the SOL. The PDL estimation was confirmed especially to sufficiently explain the fundamental characteristic of the PDL for the refractive VOA.     

Variable optical attenuator with a polymer-stabilized dual-frequency liquid crystal

A transmission-type variable optical attenuator (VOA) based on a polymer-stabilized dual-frequency liquid crystal (PSDFLC) is demonstrated at gamma = 1.55 microm. The VOA is highly transparent in the voltage-off state but scatters light in the voltage-on state. By using a birefringent beam displacer incorporated with half-wave plates, we can obtain a VOA that is polarization independent and that exhibits a 31 dB dynamic range. The polymer networks and dual-frequency effect together reduce the response time (rise + decay) of a 16 microm PSDFLC cell to 30 ms at room temperature and at a voltage of 24 Vrms.     

A new micromechanism for transformation of small displacements to large rotations for a VOA

New movement translation micromechanism (MTM) is proposed to transfer and amplify small in-plane displacement or movement into large out-of-plane vertical displacement or rotation. Based on this MTM, we may just apply 3-V dc load to generate 3.1-/spl mu/m in-plane movement, then 26.4/spl deg/ rotation angle of pop-up micromirror can be subsequently derived. An axial aligned fiber-to-fiber variable optical attenuator (VOA) device using the MTM, a U-shaped electrothermal actuator array, and the pop-up micromirror to reflect the attenuated light toward out-of-plane direction is designed and characterized. The proposed new VOA device achieves 37-dB attenuation range under 3-V dc load, while return loss, polarization-dependent loss, and wavelength-dependent loss at attenuation of 3 dB are measured as -45B, 0.05, and 0.28 dB. This new concept of steering a portion of input light toward out-of-plane direction is proven to be feasible for VOA applications.     

熔锥型光纤声光可变衰减器

利用耦合模理论对光纤熔锥声光器件进行了数值模拟,得到了全光纤声光衰减器传输谱和可调谐性。分析了带宽与声波长、耦合长度的关系。数值分析结果表明,声波在光纤熔锥中引起的轴向电介质微扰、耦合长度和工作波长都会对器件的传输谱产生影响,选择合适的设计参数可以制作较为理想的声光衰减器。实验上获得了损耗小于0．2dB,带宽大于200nm,动态范围为20dB的单模光纤熔锥可变衰减器,所得结果与理论分析相符合。这种器件可用于光纤通信及光纤传感。     

Liquid-crystal-deflector based variable fiber-optic attenuator

A compact, low-component-count, no-moving-parts variable optical attenuator (VOA) is demonstrated for the first time by means of beam spoiling that is implemented via an electrically reconfigurable nonpixelated nematic liquid-crystal deflector. The VOA design features an in-line alignment polarization-insensitive design that does not use bulky polarization splitting and combining optics. The proof-of-concept VOA at 1550 nm demonstrates a 30-dB attenuation range, a 2.5-dB insertion loss, a < or = 0.8-dB polarization-dependent loss, and a 1-s maximum attenuation reset time. The VOA design can counter performance-reducing environmental effects such as excess-loss increases due to temperature variations.     

Optical circulator for an in-line-type compact lidar

The application of an optical circulator is demonstrated for an in-line-type lidar. The lidar's transmitter and receiver are installed in a telescope. The optical circulator of interest here can separate the transmitting laser beam and the echo lights on the same optical axis. It can also divide the echo lights simultaneously into orthogonally polarized components. An insertion loss of 2.2 dB and isolation of >60 dB for the developed optical circulator are obtained in a laser-transmitting situation. This optical circulator makes it possible to measure the polarization ratio caused by cloud phases with a narrow field of view in an in-line-type lidar operation.     

GaAs超高速光调制器的研制

从理论与实验两方面研究了ＧａＡｓ定向耦合型行波光调制器，首次报导了重掺杂ｎ＾＋型薄层对电场分量相当于导体，对磁场分量相当于绝缘体这一发现；首次提出了一种具有对称宽电极的新型结构，并研制成功开关电压为８．５Ｖ，微波折射率为３．６，在３０ＧＨｚ情况下传输损耗小于１０ｄＢ／ｃｍ，根据ｓ参数测试３ｄＢ带宽达到３２ＧＨｚ的行波调制器。     

Sheathless focusing of microbeads and blood cells based on hydrophoresis

This paper presents a microfluidic device for sheathless focusing of microbeads and blood cells based on a hydrophoretic platform comprising a V-shaped obstacle array (VOA). The VOA generates lateral pressure gradients that induce helical recirculations. Following the focusing flow particles passing through the VOA are focused in the center of the channel. In the device, the focusing pattern can be modulated by varying the gap height of the VOA. To achieve complete focusing within 4.4% coefficient of variation, the relative size differences between the gap and the particle were 3 and 4 microm for 10 and 15 microm beads, respectively. Red blood cells were used to study the hydrophoretic focusing pattern of biconcave, disk-shaped particles.     

128×128 three-dimensional MEMS optical switch module with simultaneous optical path connection for optical cross-connect systems

A 128×128 three-dimensional MEMS optical switch module and a switching-control algorithm for high-speed connection and optical power stabilization are described. A prototype switch module enables the simultaneous switching of all optical paths. The insertion loss is less than 4.6 dB and is 2.3 dB on average. The switching time is less than 38 ms and is 8 ms on average. We confirmed that the maximum optical power can be obtained and optical power stabilization control is possible. The results confirm that the module is suitable for practical use in optical cross-connect systems.