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.     

Basic performance of an organic dye-doped polymer optical fiber amplifier

A polymer optical fiber amplifier (POFA) of the graded-index (GI) type, with gain in the visible region, was successfully prepared for the first time, to our knowledge, with the interfacial-gel polymerization technique. An input signal of 0.85Wat 591 nm was amplified to 420W(27-dB gain) by injection of 690W of pump power at 532 nm into a GI POFA with a 0.5-m length. The efficiency of conversion of pump energy to signal amplification was more than 60%.     

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.     

Slow light structures in dye-doped polymer waveguides

We present a simple and consistent technique for fabricating slow light structures in dye-doped polymer waveguides using the process of irreversible photobleaching. The slow light structures are moiré gratings. The gratings are holographically written into channel waveguides photobleached in side-chained PMMA/DR1 films. The films are annealed during the photobleaching process in order to remove stresses in the films generated during the photobleaching process. These stresses have been observed to cause distortion and cracking of the film surface. The slowing factor for the moiré gratings is calculated from the reflectance spectrum of the waveguides using the Hilbert transform. Moiré gratings with slowing factors between 1.6 and 2.6 are demonstrated.     

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 optical characterization of light trapping silicon nanopore and nanoscrew devices

We have fabricated nanotextured Si substrates that exhibit controllable optical reflection intensities and colors. Si nanopore has a photon trapping nanostructure but has abrupt changes in the index of refraction displaying a darkened specular reflection. Nanoscrew Si shows graded refractive-index photon trapping structures that enable diffuse reflection to be as low as 2.2% over the visible wavelengths. By tuning the 3D nanoscale silicon structure, the optical reflection peak wavelength and intensity are changed in the wavelength range of 300-800?nm, making the surface have different reflectivity and apparent colors. The relation between the surface optical properties with the spatial features of the photon trapping nanostructures is examined. Integration of photon trapping structures with planar Si structure on the same substrate is also demonstrated. The tunable photon trapping silicon structures have potential applications in enhancing the performance of semiconductor photoelectric devices.     

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.     

Fabrication and characterization of white polymer light emitting diodes using PFO:MDMO-PPV

White polymer light emitting diodes (WPLEDs) with a glass/ITO/PEDOT:PSS/PFO:MDMO-PPV/ TPBI/LIF/Al structure were fabricated in order to investigate the optimum doping concentration of the emission materials. PEDOT:PSS was introduced as the hole transport material. The PFO and MDMO-PPV were used as the light emitting host and the guest materials, respectively. The PFO:MDMO-PPV mixed solution was spin-coated onto the PEDOT:PSS/ITO substrate. TPBI, LiF and Al were deposited by thermal evaporation as the hole blocking, electron injection, and cathode materials, respectively. As a result, the current density and luminance of the WPLED with the 20.0 wt% MDMO-PPV concentration in the PFO host material were found to be about 365 mA/cm2 and 4315 cd/m2, respectively. The maximum external quantum efficiency (EQE) of the same sample was found to be 11.26%, which may be ascribed to the efficient energy transfer from the PFO host to the MDMO-PPV guest material.     

Fabrication and characterization of a nanometer-sized optical fiber electrode based on selective chemical etching for scanning electrochemical/optical microscopy

We have already reported a method for fabricating ultramicroelectrodes (Suzuki, K. JP Patent, 2004-45394, 2004). This method is based on the selective chemical etching of optical fibers. In this work, we undertake a detailed investigation involving a combination of etched optical fibers with various types of tapered tip (protruding-shape, double- (or pencil-) shape and triple-tapered electrode) and insulation with electrophoretic paint. Our goal is to establish a method for fabricating nanometer-sized optical fiber electrodes with high reproducibility. As a result, we realized pencil-shaped and triple-tapered electrodes that had radii in the nanometer range with high reproducibility. These nanometer-sized electrodes showed well-defined sigmoidal curves and stable diffusion-limited responses with cyclic voltammetry. The pencil-shaped optical fiber, which has a conical tip with a cone angle of 20 degrees , was effective for controlling the electrode radius. The pencil-shaped electrodes had higher reproducibility and smaller electrode radii (r(app) < 1.0 nm) than those of other etched optical fiber electrodes. By using a pencil-shaped electrode with a 105-nm radius as a probe, we obtained simultaneous electrochemical and optical images of an implantable interdigitated array electrode. We achieved nanometer-scale resolution with a combination of scanning electrochemical microscopy SECM and optical microscopy. The resolution of the electrochemical and optical images indicated sizes of 300 and 930 nm, respectively. The neurites of living PC12 cells were also successfully imaged on a 1.6-microm scale by using the negative feedback mode of an SECM.     

Photomechanical effects in a dye-doped polymer nanocomposite

Nile Red (NR) has been widely used as a microenvironmental probe since its luminescence characteristics depend strongly on medium polarity, viscosity, and hydrophobicity. The driving source for the internal motion of NR in rigid media is an absorbed photon that induces the molecule to rotate internally, causing the matrix deformed. Reversible (elastic) deformation and irreversible (plastic) deformation will influence the twisting dynamics in a different manner. In this work, we have investigated its excited state motion in a polymer nanocomposite, wherein polyvinyl alcohol (PVA) and nanodiamonds (NDs) were used as a matrix and a filler, respectively. PVA is a hydrophilic polymer having good chemical resistance, processability, and gel formation ability. Nanodiamond is a good candidate as a nanofiller for polymer composites. The elastic modulus of the polymer nanocomposite was measured by atomic force microscopy (AFM) nanoindentation and the emission lifetime of NR embedded in the polymer nanocomposite by time-resolved emission spectroscopy. Our results show that the fluorescence lifetime of NR is correlated well to the elastic modulus of polymer nanocomposite.     

Thin film light amplifier with optical feedback

A thin film light amplifier with optical feedback was prepared as a system consisting of a photoconductive element and an electroluminescent cell. The dependence of the brightness of the electroluminescent cell on the intensities of illumination of the photoconductive element was measured for such a light amplifier with a sinusoidal voltage supply. The characteristics obtained were compared with those calculated using the proposed theoretical model.     

Fabrication and optical modulation of top-emitting yellow light polymer light-emitting diodes on the FR4 board

Top-emitting yellow light polymer light-emitting diodes (PLEDs) were fabricated on the FR4 board for future application in optical interconnects. A 100 μm thick glass plate with sputtered Ag films on the back side for light reflection was bonded to the board for smooth surface. The PLED had a structure of indium tin oxide /poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate)/phenyl substituted polypa raphenylene-vinylene/Ba/Ag and reached the brightness of 4528 cd/m² with a corresponding current efficiency of 7 cd/A. A small AC signal imposed onto a DC bias was employed to characterize the electroluminescence delay time and hole mobility in the PDY-132 super yellow films.     

Fabrication and optical characteristics of a novel optical fiber doped with the Au nanoparticles

Optical fibers containing gold metal nanoparticles were developed by modified chemical vapor deposition, in which Au(OH)3 and tetraethyl-orthosilicate (TEOS) was used via sol-gel process to incorporate gold metals by providing the reduction atmosphere. The absorption peak appeared near 490 nm was found to be due to the surface plasmon resonance of the gold nanoparticles incorporated in the fiber core.     

Homodyne optical fiber dynamic light scattering

Optical fiber homodyne dynamic light scattering employs both the advantage of a sensitivity improvement over the standard self-beating technique and the inherent self-aligning simplicity of the optics. Ultralow concentrations of approximately nanometer-sized particles become accessible by dynamic light-scattering techniques.     

Fabrication of a graded-index polymer optical fiber preform without a cavity by inclusion of an additional monomer under a centrifugal force field

When two or more monomers with different densities and refractive indices are polymerized under a centrifugal force field, a radially varying refractive index is generated owing to the difference in density of the monomers. After the polymerization is completed, a cavity is generated about the rotational axis as a result of inherent volume shrinkage during bulk radical polymerization. Therefore it is necessary to feed an additional monomer into the cavity to compensate for the undesirable volume shrinkage. We have successfully fabricated a preform with graded indices for polymer optical fiber without a cavity by adding another monomer during rotation of the reactor. One can control the overall refractive-index profile by changing the rotation speed. Furthermore, the refractive-index profile can be predicted as a function of rotating speed by use of a simple mathematical model.     

Fabrication of a polymer-coated silver hollow optical fiber with high performance

The techniques for fabricating a hollow optical fiber with an inner silver layer and a cyclic olefin polymer (COP) layer have been improved to reduce the surface roughness of these two layers. The loss spectrum was thereby drastically reduced over a wide wavelength range, from visible to near infrared. Optimization of the COP layer thickness resulted in low loss simultaneously at several key laser wavelengths. Infrared hollow fiber with low loss was developed for Er:YAG and Nd:YAG lasers. It can also deliver green and red pilot beams with low loss. Use of this fiber in therapeutic and pilot lasers should prove useful for research and development in laser medicine.     

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.     

L波段掺铒光纤超荧光光源和放大器研究

通过优化铒光纤长度,获得了平坦谱宽达30nm(0.7dB)的L波段超荧光光源,该光源具有7.21dBm的输出功率。在此基础上,研究L波段放大器增益特性,通过对铒光纤长度的进一步优化,用1480nm激光器作前向泵浦源,实验上获得了波长从1565nm~1595nm范围平坦的增益带宽,小信号增益可达22dB。