Fabrication and characterization of dye-doped polymer optical fiber as a light amplifier

The fabrication and characterization of a Rhodamine 6G-doped polymer optical fiber amplifier have been carried out. Two different schemes were employed to characterize the optical fiber: the stripe illumination technique to study the fiber as a gain medium and another technique to study its performance as an amplifier. We observed a spectral narrowing from 42 to 7 nm when the pump energy was increased to 6 mJ in the stripe illumination geometry. A gain of 18 dB was obtained in the amplifier configuration. The effects of pump power and dye concentration on the performance of the fiber as an amplifier were also studied.     

High-power and high-gain organic dye-doped polymer optical fiber amplifiers: novel techniques for preparation and spectral investigation

Rhodamine B (RB), Rhodamine 6G (R6G), Oxazine 4 perchlorate (O4PC), and 4-Dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl-4H-pyran)-doped graded-index (GI) polymer optical fiber amplifiers (POFA's) were successfully prepared by novel techniques to prevent degradation of organic dyes and to enhance solubility of the dyes in methyl methacrylate and in poly(methyl methacrylate) (PMMA). High-power (620 W) and high-gain (33-dB, 2070 times) amplification was achieved for RB-doped GI POFA's based on the spectral investigation of dyes in PMMA bulk. It should be noted that amplification in the low-loss region of polymer optical fibers was achieved in the R6G- and O4PC-doped GI POFA.     

Fabrication and characterization of dye mixture doped polymer optical fiber as a broad wavelength optical amplifier

Rhodamine 6G and Rhodamine B dye mixture doped polymer optical fiber amplifier (POFA), which can operate in a broad wavelength region (60 nm), has been successfully fabricated and tested. Tunable operation of the amplifier over a broad wavelength region is achieved by mixing different ratios of the dyes. The dye doped POFA is pumped axially using 532 nm, 10 ns laser pulses from a frequency doubled Q-switched Nd: YAG laser and the signals are taken from an optical parametric oscillator. A maximum gain of 22.3 dB at 617 nm wavelength has been obtained for a 7 cm long dye mixture doped POFA. The effects of pump energy and length of the fiber on the performance of the fiber amplifier are also studied. There exists an optimum length for which the amplifier gain is at a maximum value.     

通信用聚合物光纤放大器

通过对掺杂有机燃料聚合物光纤放大器、掺杂稀土螯合物聚合物光纤放大器、聚合物光纤拉曼放大器以及半导体聚合物光纤放大器的基本原理和特点以及近期新发展的介绍,指出了几种聚合物光纤放大器的研究方向.     

Quantum-dot semiconductor optical amplifier performance management under optical injection

The effect of an external beam on different characteristics of quantum-dot semiconductor optical amplifiers (QD-SOAs) has been investigated experimentally. It has been shown that injection of a relatively weak light beam at the gain transparency wavelength accelerates the full gain recovery time from 80 ps to 65 ps while it increases the saturation output power (SOP) by more than 2 dB if the beam resides in the gain region. The effect of the external beam on the fiber-to-fiber gain has been demonstrated at both the gain transparency wavelength and close to gain peak wavelength. These results are expected to be further enhanced by increasing the injected beam power, which has a peak value of ～7 mW in the experiments.     

聚合物光纤预制棒的制备

本文研究了本体聚合法制备聚甲基丙稀酸甲酯聚合物光纤预制棒的方法,分析了链引发和链增长阶段温度和时间对聚合过程及聚合物光纤预制棒光谱性能的影响,并且制得了适用于光通讯低损耗窗口的光学性能较好的聚合物光纤预制棒.     

聚合物光纤光谱损耗特性的研究

截断法测量聚合物光纤 ( POF)的光谱特性是研究其损耗的一种有效方法 .用平面光栅单色仪对聚合物光纤聚甲基丙烯酸甲酯 ( PMMA)和聚苯乙烯 ( PS)的损耗光谱进行了测量 ,结果 PMMA芯 POF有三个传输窗口 ,分别为 5 2 0 nm,5 74nm,65 0 nm.在 5 2 0 nm,5 74nm处的损耗较小 ,且特性较为平坦 ,有很好的应用前景 . PS芯 POF窗口分别为 5 5 0 nm,5 80 nm,63 0 nm,670 nm,73 3 nm和 780 nm.在 5 5 0 nm,5 80 nm处同样有较好的应用前景     

Birefringence relaxation in photosensitive polymer optical fiber preform

The birefringence relaxation of photosensitive polymer optical fiber preform with low azo concentration is analyzed. Instead of bi-exponential function, tri-exponential one is introduced to describe the relaxation process. Three types of relaxation are given considering the movements of chromophores, side chains, and main chains. The conserved birefringence, which depends on the orientation of main chains, is also studied through comparison of three kinds of materials with different interaction between side chain and main chain.     

Graded-index polymer optical fiber for high-speed data communication

We successfully obtained a high-bandwidth (1 GHz km) and low-loss (90 dB/km at 0.572 μm of wavelength) graded-index polymer optical fiber by using the interfacial-gel polymerization technique, in which we used an unreactive component to obtain the quadratic refractive-index distribution. This high-bandwidth graded-index polymer optical fiber makes it possible to transmit a high-speed optical signal in a short-range network, which is not possible when we use the step-index type of polymer optical fiber commercially available.     

Switchable dual-wavelength single-longitudinal-mode erbium-doped fiber laser using an inverse-Gaussian apodized fiber Bragg grating filter and a low-gain semiconductor optical amplifier

We present a stable and switchable dual-wavelength erbium-doped fiber laser. In the ring cavity, an inverse-Gaussian apodized fiber Bragg grating serves as an ultranarrow dual-wavelength passband filter, a semiconductor optical amplifier biased in the low-gain regime reduces the gain competition of the two wavelengths, and a feedback fiber loop acts as a mode filter to guarantee a stable single-longitudinal-mode operation. Two lasing lines with a wavelength separation of approximately 0.1 nm are obtained experimentally. A microwave signal at 12.51 GHz is demonstrated by beating the dual wavelengths at a photodetector.     

Spatial structure of dye-doped polymer nanoparticle laser media

The spatial structure of dye-doped polymer-nanoparticle gain media, reported to generate spatially homogeneous single-transverse-mode laser beams, has been examined by electron microscopy in the nanometer scale. It is found that the distribution of the silica nanoparticles in the laser dye-doped polymer is fairly uniform. There is some aggregation of silica particles into loose nanoclusters. However, the nanocluster dimensions are smaller than those necessary to satisfy the conditions for internal interference in the visible spectrum. This explains the absence of macroscopic spatial inhomogeneities in the emission laser beams.     

宽带铋基掺铒光纤放大器增益及噪声特性研究

利用Er3 离子四能级结构速率方程组和光功率传输方程组,数值模拟了铋基掺铒光纤放大器(EDFA)的增益及噪声特性,模拟结果与实验报道结果取得了很好的一致。同时,详尽地分析了增益及噪声特性与光纤长度、泵浦功率和输入信号功率的关系,优化了放大器的性能,从理论上得出一个20dB增益带宽达76nm、噪声系数接近4dB的铋基EDFA。研究表明了铋基掺铒光纤放大器适合用作于现代DWDM系统中C L波段的光纤放大器。     

Helicons in an optical fiber

Solutions for nonlinear helical electric and magnetic waves and polarization modes in a quartz fiber are found. Parameters of these modes (the normal velocity of the wave front and the helix pitch) are calculated as functions of the fiber properties and the amplitude and frequency of the electromagnetic field.     

High-bandwidth, graded-index polymer optical fiber for near-infrared use

We describe graded-index polymer optical fibers with high bandwidth (5.12 GHz for 100-m transmission) and low loss in the near-infrared region (56 and 115 dB/km at wavelengths of 688 and 773 nm, respectively) that we successfully obtained with a new interfacial-gel polymerization technique using an all-deuterated methyl methacrylate monomer and a partially fluorinated acrylate monomer. The necessity for both low attenuation and high bandwidth for a polymer optical fiber is described for its use as a physical media in a high-speed multimedia network.     

Multimode laser emission from dye doped polymer optical fiber

Multimode laser emission is observed in a polymer optical fiber doped with a mixture of Rhodamine 6G (Rh 6G) and Rhodamine B (Rh B) dyes. Tuning of laser emission is achieved by using the mixture of dyes due to the energy transfer occurring from donor molecule (Rh 6G) to acceptor molecule (Rh B). The dye doped poly(methyl methacrylate)-based polymer optical fiber is pumped axially at one end of the fiber using a 532 nm pulsed laser beam from a Nd:YAG laser and the fluorescence emission is collected from the other end. At low pump energy levels, fluorescence emission is observed. When the energy is increased beyond a threshold value, laser emission occurs with a multimode structure. The optical feedback for the gain medium is provided by the cylindrical surface of the optical fiber, which acts as a cavity. This fact is confirmed by the mode spacing dependence on the diameter of the fiber.     

Chemical and optical properties of dye-doped sol-gel films

Sol-gel silica coatings doped with an acid indicator were prepared and their behaviour vs pH in aqueous media were studied. Absorption spectroscopy was used to characterize the reversible optical response of doped films both in liquid and gaseous media. Several features such as: a) strong influence of acid concentration on films colour change, b) reversibility without fatigue all over the pH range, and c) spontaneous regain of initial basic absorption when coatings were sensitized under acid vapour; pointed out that dye molecules were incorporated in the surface of the silica films pores. On the other hand, coatings resistance vs alkaline attack showed that damage quickly proceeded if films surface were inhomogeneous, due to direct corrosion of the glass substrate.     

GSM-R光纤直放站低噪声放大器模块的设计

对满足铁路专用数字移动通信系统(GSM-R)标准的光纤直放站低噪声放大器模块进行了设计、制造和测试.放大器模块由四级放大电路构成,可提供高的增益和线性度.输入级采用双平衡放大结构,不仅能改善放大器级间匹配性,而且由于具有冗余备份功能,可提高模块的可靠性.采用数模混合自动增益控制技术保证低噪声放大器的输出功率稳定和高动态范围.测试结果表明,该模块最大增益达到60dB,增益调节范围大于30dB,互调衰减小于-60dBc,噪声系数小于1.0dB,体现了优异的线性度和噪声性能.该模块完全达到GSM-R高铁直放站的设计要求,目前已通过南京泰通科技的实际应用测试,并开始试应用于铁路系统中.     

Detection of acetone vapor using graphene on polymer optical fiber

Recently, many studies have been focused on the development of fiber optic sensor systems for various gases and vapors. In the present study, an intrinsic polymer optical fiber (POF) sensor using graphene is described for the purpose of acetone vapor sensing for the first time. Observations on the continuous measurement of acetone vapor in dehydrated air are presented. The principle of operation of sensor transduction relies on the dependence of the reflectance on the optical and geometric properties of the sensitive over layered when the vapor molecules are adsorbed on the graphene film. For the same purpose the CVD synthesized graphene film was transferred on the POF end. The synthesized graphene film thickness was evaluated using atomic force microscopy (AFM), Raman spectroscopy and transmission electron microscopy (TEM). For the preliminary evaluation using volatile organic compounds, we evaluated the sensor performance for acetone. Upon the interaction of the sensor with acetone vapor, the variation in the reflected light was monitored as a function of the acetone concentration. The sensor response shows a significant change in sensitivity as compared with the POF probe without a graphene coating. The present sensor shows a satisfactory response upon exposure to various concentrations of acetone vapor from 44 ppm to 352 ppm. To the best of our knowledge, the use of graphene film along with POF for the sensing of volatile organic compounds has not previously been reported.     

Suppression of self-pulsing behavior in erbium-doped fiber lasers with a semiconductor optical amplifier

We experimentally demonstrate that the stability of cw and mode-locked erbium-doped fiber ring lasers can be improved significantly with a semiconductor optical amplifier (SOA) inside the cavity. The fast saturable gain of the SOA suppresses significantly the self-pulsing that is due to ion pairs in the erbium-doped fiber, which acts as a saturable absorber. A linear stabilization analysis of the laser system agrees with our experimental results.