Lili Wang

Casting preforms for microstructured polymer optical fibre fabrication

A monolithic structured polymer preform was formed by in-situ chemical polymerization of high-purity MMA monomer in a home-made mould. The conditions for fabrication of the preforms were optimized and the preform was drawn to microstructured polymer optical fibre. The optical properties of the resultant elliptical-core fibre were measured. This technique provides advantages over alternative preform fabrication methods such as drilling and capillary stacking, which are less suitable for mass production.

Fabrication and experimental observation of monolithic multi-air-core fiber array for image transmission

Two kinds of multi-air-core optical fibers were designed and fabricated by extruding optical grade PMMA pellets and drawing to fiber. The imaging function of the fibers was investigated with home-made specialized microscopy. This new type of fiber provides strong potential for applications in endoscopy, chemical sensing, biosensors, fiber-optical faceplates.

Dye-doped Microstructured Polymer Optical Fibre Laser with High Numerical Aperture Air-clad

We demonstrated a Hemicyanine dye-doped microstructured polymer optical fibre laser generating up to 200 mW output power with a slope efficiency of 20% and a high numerical aperture air-clad at the wavelength of 578 nm.

Mass-fabrication of air-core microstructured polymer optical fiber

An air-core, 252 holes cladding, 51% air-occupied fraction PMMA-based MPOF as successfully fabricated by drawing an extruded 253 holes preform. With the extrusion technique, air-core MPOF preform could be produced on a large scale.

Research on gradient index material containing silver ions

Since the gradient index material has important applications at photoelectric system, imaging system, and integrated-optical system. Now, researches on gradient index material containing silver ions are more popular, it is difficult to get glass with high silver content as silver ion is extruded from molten glass at the molten temperature. Two-step ion-exchange process including Ag +- Na+ and Na+ - Ag + ion-exchange is used to get gradient index. This paper is based on the research in our lab, by adjusting the glass composition to get a series of sodium-rich glass then drawing the fusioned glass into fiber with diameter of 1mm used for ion-exchange. We used mixed molten salt for ion- exchange, then we researched on the choice of silver salt, the advantage and disadvantage of mixed molten salt and single molten salt, and the coloring up problem after ion-exchange.

Fabrication of microstructured polymer optical fiber preform

We report a new technology to fabricate microstructured polymer optical fiber (MPOF, also named polymer photonic crystal fiber, pPCF) preform rods by in-situ polymerization of monomer in a mould. Series of pPCF preform rods including elliptic core fiber preform rod, single-mode fiber preform rod and ring-type holes structured preform rods have been fabricated. The optimum conditions for monomer-based fabrication of pPCF preform rods were investigated. Then, drawing from primary preform rods to secondary preform rods was carried out in a home-made furnace. Finally, optical and thermal properties of these pPCF preform rods, such as transmittance, a glass transition temperature, and the distribution of molecular weight were investigated. Optically functional dye-doped pPCF preform rods, rhodamines-doped PMMA preform rods were successfully fabricated.

Highly efficient tunable tapered-polymer-fiber lasers

A highly efficient tunable tapered-polymer-fiber (TPF) laser was demonstrated by use of a compound parabolic TPF doped with Rhodamine-6G (R6G) dye. The tuning ranges over 40 nm at the visible region for laser output with the maximum output energy of 600 mu J at 570 nm and the optical-optical conversion efficiency of 23% were achieved by a prism as a spectrally selective element. Moreover, the coupling efficiency for the taper exceeded 90%. Compared to traditional polymer fibers with a micrometer-size core diameter, the taper allows for a higher pump to be launched without damaging the fiber endfaces, and it can efficiently couple the light into the fiber and alleviate the alignment difficulty. So, the TPF laser not only possesses all of the advantages of traditional polymer-fiber lasers, and it can also obtain higher output energy and higher efficiency. Additionally, it is insensitive to geometrical displacements. (c) 2005 American Institute of Physics.

Polymer-based microstructured fiber towards imaging application

PMMA-based MOF with 547 air holes was fabricated by extruding and stretching of an big-size preform with hole diameter of 1.5 mm and hole spacing of 1.9 mm. The high image resolution was demonstrated.

Fabrication of low-cost polymer microlens array

The fabrication technology of refractive microlens array (MLA) with self-assembly of drops of various thermoplastic optical polymer solutions is reported. In order to develop a conventional drop-on-demand type ink-jet printing method for fabricating high quality microlens array, Firstly, we tried to prepare a series of optical polymer inks. These inks compose of high quality optical polymers, polymethylmethacrylate (PMMA), dopant, and functional organic molecules such as laser dye, nonlinear organic dye, and rare earth ion chelates with a suitable organic solvent. Effects of surface tension on the polymer solution drops induced the self-formation of microlenses. This process exhibited a completely self-assembly characteristic without any chemical and photochemical post-treatment. The resulting microlens array displayed diameters varying from 1mm to 5mm and focal lengths from less than one millimeter to a few millimeters. Observation with an atomic force microscope reveals that the surface roughness of the lens is 0.9 nm. The transmittance spectrum of the lens is also measured.

Real-time non-destructive testing of dynamic holograms in doubly-doped LiNbO3 crystals using phase-conjugate technique

To test the dynamic photorefractive grating during holographic recording, as usual, the signal wave is blocked from time to time and simultaneously the diffracted beam of the reference wave is tested. This kind of measurement destroys the continuity of the holographic recording and increases the random noise and results in bad repeatability and reliability. In this paper, the phase-conjugate technique is used to overcome the above drawbacks. The reference wave and the object wave are much stronger than the probe beam propagating along the counter-direction of the reference wave. Thus the real-time and non-destructive testing of the dynamic holograms can be obtained by measuring the phase-conjugate wave of the object wave.