Peng Jinggang

All-Fibre Ytterbium-Doped Photonic Crystal Fibre Laser with High Efficiency

A double-cladding ytterbium-doped photonic crystal fibre (PCF) with a 350-μm2 effective area is fabricated. The measurement results show that the PCF has high absorption peak at 915 nm. Its fluorescence lifetime is 840μs. Laser experiments with all-fibre configurations are carried out with this fibre. A continuous-wave output power of 3.96 W is achieved with a 5.2 W launched pump power. The central wavelength of the output spectrum is 1080.22nm. The results show that the PCF laser has a high slope efficiency of 79.6% and light conversion efficiency of 76.2%.

Controlling the Spectral Characteristics of Bismuth Doped Silicate Glass Based on the Reducing Reaction of Al Powder

Silicate glasses co-doped with Al metal powder and Bi2O3 are prepared. The effects of Al on spectral properties of samples are studied. It is found that the absorption intensity increases with increasing Al concentration in bismuth doped silicate glasses. The near-infrared (NIR) emission of the samples can be controlled by Al powder concentration no matter whether or not excited by 808 nm or 976 nm lasers. Furthermore, the influence of Al on formation of Bi-NIR active ions is discussed. The dependence relationship between the emission property of ~416 nm and Al concentration is a way to investigate the NIR emission origin of bismuth doped glass.

Fabrication of Tm-Doped Fibers for High Power and 121 W Output All-Fiber Tm-Doped Fiber Laser*

We fabricate the Tm-doped double cladding silica fiber by using the vapor-solution hybrid-doping method, then build up an all-fiber Tm-doped fiber laser which can provide the output power of up to 121 W, corresponding to a slope efficiency of 51% and an optical-optical efficiency of 48%. By using the domestic Tm-doped fiber, it is the first time a hundred-watt level output at 1915nm has been achieved, to the best of our knowledge. The thermal effect of Tm-doped fiber laser is also analyzed.

A kW Continuous-Wave Ytterbium-Doped All-Fiber Laser Oscillator with Domestic Fiber Components and Gain Fiber *

We demonstrate a kW continuous-wave ytterbium-doped all-fiber laser oscillator with all domestic fiber components: a 7 × 1 fused fiber bundle combiner, a fiber Bragg grating and a double-clad gain fiber. The oscillator operates at 1079.48 nm with 80.94% slope efficiency and shows no limit of temperature and nonlinear effects. These indicate that the passive fiber components and the gain fiber are all qualified for the high power environment. No evidence of the signal power roll-over shows that this oscillator possesses the capacity to higher output with available pump power.

Photodarkening-Induced Absorption and Fluorescence Changes in Yb Fibers

We study the photodarkening effect in a double clad ytterbium-doped silica fiber fabricated by modified chemical vapor deposition and solution doping. A common measurement technology for photodarkening is used to study the photodarkening-induced absorption spectra. We present a fast and simple method to observe the PD effect by measurement of the fluorescence spectra. The method proposed here can be used to observe the influence for a short time, and thus reduces the requirements of system stability and heat management. It is obtained that under the condition of 45.5% Yb ion inversion level, photodarkening-induced excessive loss at an equilibrium state is above 4.5dB/m and florescence intensity degradation is above 10% after 500min pumping at 1041 nm for the home-made normal Yb/Al co-doped silica fiber.

Blue-Extended Supercontinuum Generation in Photonic Crystal Fibers with Picosecond Pulse Pumping

We report supercontinuum generation extending to the blue spectral region using pulses of 1.8 ps duration at 1040 nm in GeO2-doped core photonic crystal fibers. A spectrum in fundamental mode spanning from 415 nm to beyond 1750 nm is generated in a uniform photonic crystal fiber (PCF). A zero dispersion wavelength decreasing PCF is fabricated to optimize the parameters for deeper blue components generated by cross-phase modulation and group-velocity matching. Although the PCF is pumped at a low input power of 1.3 W in anomalous dispersion and relatively far from the zero dispersion wavelength, a flat continuum covering 406.1?671.8 nm is generated, which is of primary importance in a number of bio-photonic applications such as fluorescence imaging microscopy.

Enhanced Visible Light Generation from 1 μm Femtosecond Pulses within High-Δ Photonic Crystal Fibers

We demonstrate the blue light generated in high-Δ photonic crystal fibers (PCFs). A femtosecond Yb-doped fiber laser, operating at 1039nm, is used to pump a GeO2-doped PCF in the largely anomalous group velocity dispersion (GVD) region. The emitted radiation covers 418.6–544.6nm with 5dB flatness. The calculated result indicates that the cross phase module (XPM) effect induced by higher-mode soliton makes a contribution to the blue component generation.

Numerical Study of Plasmonic Modes in Hexagonally Arranged Metal Nanowire Array

A plasmonic waveguide containing hexagonally arranged parallel metallic nanowires with hexagonal cross sections embedded in a silica fiber is proposed and discussed. According to simulations of surface plasmon polariton eigenmodes at varying geometrical transverse parameters, we obtain comprehensive mode characteristics, including field mode distribution, effective refractive index, propagation length, and lateral mode radius, thus allowing us to investigate the precise trade-off between propagation length and confinement, which is very important in designing plasmonic waveguides of different applications. This waveguide is also proved to be robust against fabrication imperfections, which makes its manufacture and practical applicability feasible.