Kang Xie

Polarization splitter based on dual-core photonic crystal fiber

A polarization splitter based on a new type of dual-core photonic crystal fiber (DC-PCF) is proposed. The effects of geometrical parameters of the DC-PCF on performances of the polarization splitter are investigated by finite element method (FEM). The numerical results demonstrate that the polarization splitter possesses ultra-short length of 119.1 μm and high extinction ratio of 118.7 dB at the wavelength of 1.55 μm. Moreover, an extinction ratio greater than 20 dB is achieved over a broad bandwidth of 249 nm, i.e., from 1417 nm to 1666 nm, covering the S, C and L communication bands.

High birefringence photonic crystal fiber with high nonlinearity and low confinement loss

A particular photonic crystal fiber (PCF) designed with all circle air holes is proposed. Its characteristics are studied by full-vector finite element method (FEM) with anisotropic perfectly matched layer (PML). The simulation results indicated that the proposed PCF can realize high birefringence (up to 10(-2)), high nonlinearity (50W(-1)·km(-1) and 68W(-1)·km(-1) in X and Y polarizations respectively) and low confinement loss (less than 10(-3)dB/km at 1.55um wavelength).

Polarized random laser emission from an oriented disorder polymer optical fiber

We demonstrate the realization of a polarized random polymer fiber laser (RPFL) in the different disordered gain media doped polymer optical fibers (POFs). Multiple scattering of disordered media in the orientated POF was experimentally verified to account for polarized lasing observed in our RPFL system. This Letter presents a new avenue for fabricating polarized RPFLs in a large scale. Meanwhile, the polarization-maintaining property of random lasing for different disorder POF are researched, which will open a window to designing a polarization-maintaining random fiber laser.

Dual-Core Photonic Crystal Fiber for Use in Fiber Filters

An asymmetrical dual-core photonic crystal fiber (DC-PCF), which possesses all circular air holes, is proposed. By setting appropriate geometrical parameters, the wavelength-selective coupling property is realized, and a compact optical filter with a short length of 1.83 mm based on the DC-PCF is designed. The spectral transmission characteristics of the filter are investigated by the beam propagation method. The results demonstrate that the optical filter possesses a bandwidth of ~58 nm and small sidelobes. The proposed optical filter could be used in the integrated optical systems.

Gold nanoparticle-based plasmonic random fiber laser

We have reported the realization of a plasmonic random fiber laser based on the localized surface plasmonic resonance of gold nanoparticles (NPs) in the liquid core optical fiber. The liquid core material contains a dispersive solution of gold NPs and laser dye pyrromethene 597 in toluene. It was experimentally proved that the fluorescence quenching of the dye is restrained in the optical fiber, which is considered one of the main sources of loss in the traditional laser system. Meanwhile, the random lasing can be more easily obtained in the random laser system with more overlap between the plasmonic resonance of the gold NPs and the photoluminescence spectrum of the dye molecules.

Modulation of large absolute photonic bandgaps in two-dimensional plasma photonic crystal containing anisotropic material

The large absolute photonic bandgaps of two-dimensional (2D) anisotropic magnetic plasma photonic crystals with hexagonal and square lattices are obtained by introducing tellurium dielectric rods using the modified plane wave expansion method. Equations for calculating the band structures in the irreducible part of the first Brillouin zone are theoretically deduced. The modulation properties indicate that the location and bandwidth of the absolute photonic bandgaps (PBGs) could be tuned by filling factor, plasma frequency, and magnetic field. The effective tunable ranges and critical values of these parameters are found. These results could be helpful in designing 2D anisotropic PPCs with large absolute PBGs.

Random lasing from dye doped polymer optical fiber containing gold nanoparticles

We have demonstrated the realization of a plasmonic random polymer fiber laser (RPFL) based on gold nanoparticles (NPs) doped one-dimensional disordered gain polymer optical fiber (POF). In this work, the plasmonic RPFL is fabricated by directly drawing from a laser dye and gold NPs system codoped POF. The random lasing can be obtained from the waveguide-plasmon-scattering in the POF system. Meanwhile, the dye doped fiber in the presence gold NPs has high photostability.

Wavelength control of random polymer fiber laser based on adaptive disorder

We demonstrate the realization of two different kinds of random polymer optical fiber lasers to control the random lasing wavelength by changing the disorder of polymer optical fibers (POFs). One is a long-range disorder POF based on copolymer refractive-index inhomogeneity, and the other is a short-range disorder POF based on polyhedral oligomeric silsesquioxanes scattering. By end pumped both disorder POFs, the coherent random lasing for both is observed. Meanwhile, the random lasing wavelength of the short-range disorder POF because of a small scattering mean-free path has been found to be blue shifted with respect to the long-range disorder POF, which will give a way to control the random lasing wavelength.

Tunable random polymer fiber laser

We have demonstrated the realization of on-line temperature-controlled random lasers (RLs) in the polyhedral oligomeric silsesquioxanes (POSS) nanoparticles (NPs) as well as Pyrromethene 597 (PM597) laser dye, Fe3O4/SiO2 NPs as well as PM597, and only PM597 doped polymer optical fibers (POFs), respectively. The RLs can be obtained from the gained POFs system caused by multiple scattering of emitted light. The refractive index of the fiber core materials can be easily tuned via temperature due to the polymer with large thermo-optic coefficient. Meanwhile, the scattering mean free path of core in the POFs, which is the key role for the emission wavelength of RLs, is strongly dependent on the matrix refractive index. Thus emission wavelength of RLs in the POF temperature can be controlled through changing the temperature. With the increasing the temperature, the RL emission wavelength has occurred red-shift effect for the POFs.

Coherent random lasing from nano-scale aggregates of hybrid molecules by enhanced near zone scattering

Nano-scale aggregates of hybrid molecules, such as N,N′-di-[3-(isobutyl polyhedral oligomeric silsesquioxanes)propyl] perylene diimide (DPP) which is composed of perylene diimide (PDI) as gain group and polyhedral oligomeric silsesquioxanes (POSS) as scattering group at a mole ratio of 1:2, are formed in carbon disulfide (CS2) solution within a concentration range from 3 × 10−5 M to 10−3 M. The aggregation of DPP in the solution was characterized using ultraviolet visible (UV-vis) and fluorescence spectroscopy. Under pumping of a 532 nm pulse laser, coherent random laser (RL) is produced from the aggregates in CS2 solution with a threshold of 17.4 μJ and a Q value of 2440 at a DPP concentration of 10−4 M. Enhanced near zone scattering by aggregation is thought to boost coherent RL. This research not only extends the RL system to the extremely weak scattering regime but also provides a new direction for research on nano-scale materials for lasers using molecular design.