锥形光纤在光纤传感和光纤激光器上的应用

介绍了近年来得到广泛研究的锥形光纤技术的发展现状,尤其是在光纤传感和光纤激光器上的应用.在光纤上直接拉制出的锥区可用于制作小型化、一体化、具有许多优良光学特性的光纤器件.锥形光纤按束腰直径和光纤拉锥区的长度比,可分为锐锥度光纤(锥区长度和锥区的束腰直径较接近)和缓锥度光纤(锥区的长度远远大于束腰的直径).锐锥度光纤可以制作Michelson或者Mach-Zehnder干涉仪可用来实现折射率传感器;同时它还可改变激光光斑的强度分布,获得平顶光斑输出.利用单模缓锥度光纤可以实现窄线宽可调谐滤波器;另外基于缓锥度光纤可以实现多模光纤至单模光纤的转换器.锥形光纤结构紧凑,制作简单、成本低,必将成为多种实用光纤器件的核心.     

基于光纤锥和多模渐变光纤的马赫-曾德尔干涉仪的传感特性研究

提出了一种基于光纤锥和纤芯失配光纤结构的马赫-曾德尔干涉(MZI)传感器。在距离单模光纤(SMF)锥25mm处熔接一段长30mm的多模渐变光纤(GI MMF),形成SMF-光纤锥-SMFGI MMF-SMF结构。其中,光纤锥起到增加包层模能量的作用,GI MMF为传感臂。传感器外界环境温度、折射率及应力的改变都会使传感器的纤芯基模和包层模的光程差发生改变,从而引起传感器干涉谱发生变化,通过监测干涉谱的变化可以实现对外界物理量的测量。实验研究结果表明,当环境溶液温度在30~89℃范围内变化时,传感器的温度灵敏度为78.6pm/℃,线性度为0.997;环境溶液折射率在1.333~1.394变化范围内,传感器的折射率灵敏度为81.48dB/RIU,线性度为0.989;轴向应变在0~933.3με变化范围内,传感器的应变灵敏度为0.33×10-2 dB/με,线性度为0.998。本文传感器可以实现多个物理量的同时区分测量。     

Multi-wavelength fiber laser based on broadband fiber grating and HiBi fiber loop mirror

Multi-wavelength fiber lasers have attracted a lot of in- terest in recent years because of its potential applications in optical wavelength division multiplexing (WDM) systems, fiber sensors, and other fiber-optics instruments. Because of the predominant…     

基于稀土掺杂石英光纤的单频光纤激光器

系统研究了利用稀土掺杂的石英光纤作为激光增益介质来实现分布布拉格反射式单频光纤激光器。实验中,分别将掺有Nd3+、Yb3+、Er3+/Yb3+和Tm3+的商用石英光纤,熔接到激光谐振腔中,实现了基于石英玻璃光纤的光纤激光系统在多波段的单纵模运转。对各光纤激光器的单频特性进行了研究,其中,激光器线宽可达几十千赫（特别是对于Er3+/Yb3+共掺光纤激光器,其线宽窄于7 kHz）,激光系统的强度噪声接近于散粒噪声极限,实验中获得了激光波长由930 nm到2m的单频光纤激光器。实验结果证明:商用的稀土掺杂石英光纤能够作为有效的增益介质来实现短腔型单频光纤激光器。同时,通过进一步的系统集成,基于稀土掺杂石英光纤的单频光纤激光器将得到更加广泛的应用。     

Single-mode hole-assisted fiber as a bending-loss insensitive fiber

We investigate the design and characteristics of a single-mode and low bending loss HAF both numerically and experimentally. An air filling fraction S is introduced to enable us to design a HAF with desired characteristics more easily. We show that we can expect to realize a single-mode and low bending loss HAF by considering the S dependence of the bending loss α_b and cutoff wavelength λ_c as well as their relative index difference Δ dependence. We also show that the mode-field diameter (MFD) and chromatic dispersion characteristics of the single-mode and low bending loss HAF can be tailored by optimizing the distance between the core and the air holes. We also investigate the usefulness of the fabricated HAFs taking the directly modulated transmission and multipath interference (MPI) characteristics into consideration. We show that the designed HAF has sufficient applicability to both analog and digital transmission systems. Our results reveal that the single-mode and low bending loss HAF is beneficial in terms of developing a future fiber to the home (FTTH) network as well as for realizing flexible optical wiring.     

L-band multiwavelength fiber laser using an elliptical fiber

In this letter, we propose and demonstrate a simple and novel technique to get multiwavelength operation in the L-band by using an elliptical core erbium-doped fiber. The principle of operation is based on the anisotropic gain effect in a polarization-maintaining fiber. Stable multiwavelength operation is achieved at room temperatures. The lasing lines may be controlled by a polarization controller     

Novel fiber sensor arrays using erbium-doped fiber amplifiers

We examine the signal-to-noise ratio (SNR) performance of a novel type of time domain multiplexed sensor arrays in which low gain (1-10 dB) fiber amplifiers are incorporated to compensate for splitting losses between sensors. The system noise figure for passive and amplified sensor arrays is presented, along with expressions to optimize the array parameters for high SNRs. We show that practical amplified sensor arrays exhibit low system noise figures that allow much larger arrays (hundreds of sensors) than passive arrays     

气压式光缆系统

气压式光缆系统是解决光纤接入最用户的方案之一,本文介绍了构成该系统的传送理论及主要部件的结构,并对其机械特性、压送特性、传输特性等进行了比较全面的分析与评估。     

光子晶体光纤在光纤激光器中的应用

光子晶体光纤研究的日趋成熟不仅拓宽了光纤激光器的研究领域,同时也推动了激光技术的发展.文章针对大模面积双包层光子晶体光纤的特点,探讨了其在光纤激光器中的应用,重点阐述了光子晶体光纤在光纤激光器应用领域的最新进展,并介绍了燕山大学在制备稀土掺杂光子晶体光纤上所取得的最新成果.     

Switchable and tunable multiwavelength erbium-doped fiber laser with fiber Bragg gratings and photonic crystal fiber

We propose and report on a novel multiwavelength-switchable-tunable erbium-doped fiber laser with excellent stability and uniformity based on four-wave mixing (FWM) in a highly nonlinear photonic crystal fiber. By adjusting the attenuators, the single, dual, or triple wavelengths can be lasing simultaneously. Under the influence of the FWM, the spectrum is stabilized and the uniformity is less than 0.6 dB.     

Gain-clamped fiber amplifier with a short length ofpreamplification fiber

Although gain-clamping an erbium-doped fiber amplifier (EDFA) by a counterpropagating ring resonator prevents oscillation light from being output, it degrades the amplifier's noise figure. The noise figure degradation can be reduced by using a length of EDF, that is short enough not to cause any gain saturation, for preamplification. Experiments confirm that the prestage EDFA reduces the noise figure degradation under constant gain operation     

多泵浦与光纤级联结合的宽带拉曼光纤放大器

针对传统光纤通信传输系统中拉曼光纤放大器(RFA)增益带宽不足、输出增益低且输出增益不平坦的问题,设计了一种多泵浦和光纤级联相结合的宽带拉曼光纤放大器。并且推导实现增益平坦输出时所用六个泵浦光和四段光子晶体光纤(PCF)对应参数满足的约束表达式,从理论上给出了一种提高放大器增益和增益带宽的同时保证较小增益平坦度的设计方法。最后通过Matlab数值模拟,所设计的宽带拉曼光纤放大器达到了增益带宽92 nm,平均增益39.95 dB,增益平坦度0.1447 dB。     

Very flat gain erbium-doped fiber amplifier using samarium-doped fiber

A two-stage erbium-doped fiber amplifier (EDFA) with extremely flat gain (/spl plusmn/0.1 dB) over 17-nm bandwidth is demonstrated. The gain flatness is achieved by incorporating samarium-doped fiber in the mid section of the amplifier.     

双泵浦两段高非线性光纤级联的光纤参量放大器

提出和设计了一种宽带宽、高增益和增益平坦的光纤参量放大器,它具有双泵浦和两段高非线性光纤级联的结构.选择光纤的四阶色散系数作为优化的指标之一,用普通的数组循环计算法,对双泵浦及两根高非线性光纤组成的系统进行模拟,获得了峰值增益62.46 dB,起伏小于5 dB,带宽高达424nm的光纤参量放大器.     

基于级联光纤环形镜的增益平坦掺铒光纤放大器

基于光纤环形镜的滤波原理,提出利用级联结构光纤环形镜(FLM)实现掺铒光纤放大器(EDFA)增益平坦滤波的方案,并进行了相关实验研究.实验结果显示,使用级联FLM取得了明显的增益平坦效果,其1535-1557nm波长范围内的增益不平坦度由±5dB减小到±1dB.     

基于SESAM的被动调Q光纤光栅掺铒光纤激光器

提出并研究了一种线性腔结构的基于 SESAM(半导体可饱和吸收镜)的被动调 Q光纤光栅掺铒光纤激光器,该激光器无需采用偏振控制器控制激光偏振态,简化了调 Q 激光器的结构。该激光器的中心波长为1549.975 nm,阈值功率为143 mW,斜效率为1.2%。当泵浦功率从149 mW增加到180 mW时,脉冲重复频率从5.431 kHz增加到9.778 kHz。当泵浦功率为155 mW时,激光脉冲的能量为5.6 nJ,重复频率为6.538 kHz,脉冲宽度为40μs。     

Phase error bounds of fiber gyro with polarization-holding fiber

Phase error bounds for a fiber gyro with an imperfect polarizer are calculated assuming a broad-band source and high-birefringence fiber. The phase error and resulting zero-point drift is related to the polarization-holding parameterhof the fiber. Comparison of the theory with recent experimentally observed bias drift is made.     

光纤布喇格光栅在光纤通信中的应用

文章介绍了一种新型的光无源器件－芯内光纤布喇格光栅在光纤通信领域中的应用，分析了光纤布喇格光栅器件的性能以及存在的某些问题。     

Passive gain-equalized wide-band erbium-doped fiber amplifier using samarium-doped fiber

A passive gain-equalization technique of erbium-doped fiber amplifier (EDFA) using a samarium-doped fiber to obtain wide-band flattened gain operation is reported. In the wavelength range from 1529-1559-nm, small inter-channel gain variations can be achieved. This simple technique is suitable for multiwavelength wide-band in-line-amplifier cascaded transmission applications.     

A high-stability fiber amplifier source for the fiber opticgyroscope

We demonstrate an erbium-doped fiber amplifier (EDFA) source for the fiber gyroscope with an overall mean wavelength stability of four parts per million. This source, which amplifies the gyroscope signal before detection, is shown to be more stable than a similar single-pass source in a standard configuration. The effects of varying the fiber temperature, pump power, pump wavelength, gyroscope feedback power and signal polarization state on the output mean wavelength are individually explored. Experimental results are in excellent agreement with simulations