Jiantao Liu

Yb-doped silica glass and photonic crystal fiber based on laser sintering technology

We demonstrate the fabricating method for Yb3+-doped silica glass and double-cladding large mode area photonic crystal fiber (LMA PCF) based on laser sintering technology combined with a liquid phase doping method. The doped material prepared shows the amorphous property and the hydroxyl content is approximately 40 ppm. The attenuation of the fabricated LMA PCF is 14.2 dB m−1 at 976 nm, and the lowest value is 0.25 dB m−1 at 1200 nm. The laser slope efficiency is up to 70.2%.

Wide-band tunable passively Q-switched all-fiber ring laser based on nonlinear polarization rotation technique

A wide-band tunable passively Q-switched all-fiber ring laser based on nonlinear polarization rotation (NPR) technique is demonstrated. The NPR-induced intensity-dependent loss effect acts as an artificial saturable absorber, which was used to achieve the Q-switched operation with a low pump threshold of about 25 mW. Taking advantage of the intracavity birefringence-induced spectral filtering effect, the central wavelength of Q-switched pulse can be continuously tuned from 1543.4 to 1592.4 nm by simply rotating the PCs.

Design and fabrication of ytterbium-doped photonic crystal fiber with low non-linearity

We report on an ytterbium-doped photonic crystal fiber fabricated by laser sintering technology combined with a solution doping method. This novel fabrication process has never been reported to the best of our knowledge. Together with low non-linearity, this PCF combines the advantages of high pump absorption efficiency and bend-insensitive, which makes this fiber predestinated for the high power fiber laser applications. The fiber laser experiment was conducted with a simple Fabry–Perot cavity to verify the performance of the PCF. A high slope efficiency of ~70.6% was obtained from a 1.5 m-long fiber. During the experiment, no roll over was observed up to the highest power level, which was only limited by the available pump power. The experimental results reveal the enormous output power scaling potential of the PCF.

Optical properties of the Yb/Er co-doped silica glass prepared by laser sintering technology

Yb/Er co-doped silica glass is the critical core material in the fabrication for Yb/Er co-doped optical fiber. In this paper, we demonstrate the novel laser sintering technology for making the Yb/Er co-doped silica glass rod, and analyze its physical and optical properties. The experimental results show that the fabricated silica glass is amorphous, and Yb3+/Er3+ ions uniformly distribute in the glass matrix. The material presents very good emission property around 1535 nm, and the calculation result of the gain cross section also indicates the good gain property at the emission band. Moreover, the Judd-Ofelt analysis results show that the material has very attractive spectroscopic parameters. These results can be used as good reference for the fabrication of Yb/Er co-doped optical fibers used for high-power fiber lasers in the future.

Surface Plasmon Resonance on the V-Type Microstructured Optical Fiber Embedded with Dual Copper Wires

Microstructured optical fiber can be used as polarized filters by filling the metal into the air holes in cladding to generate surface plasmon resonance. In this paper, we present a V-type birefringence microstructure optical fiber with embedded dual copper wires that were made by the stack-drawing method, and the dual copper wires were aligned in the vertical direction symmetrically. Through adjusting the fiber structure parameters, we found the fiber can be easily excited strong surface plasmon resonance in the S and L waveband. Then the core mode is completely coupled into the copper wires and generates the surface plasmon resonance in the y-polarized direction, to achieve the purpose of directional filtering. The experimental results are consistent with the theory.

Experimental study on all Yb-doped photonic crystal fiber laser

In this paper, we demonstrated an experiment of the all Yb-doped photonic crystal fiber laser using free space optical paths method. The experimental setup of all Yb-doped photonic crystal fiber laser is composed of the seed laser and the amplifier. The laser gain medium of the seed laser and the amplifier are the same Yb-doped photonic crystal fibers that are fabricated by non-chemical vapor deposition (Non-CVD) technology. The seed laser cavity is a Fabry-Perot cavity. The amplifier is pumped by back-end method. They are coupled each other by lens and dichroic mirrors on the optical table. The experimental results have a good reference value for the photonic crystal fiber laser research in the future.

Studies on output characteristics of stable dual-wavelength ytterbium-doped photonic crystal fiber laser

A stable dual-wavelength ytterbium-doped photonic crystal fiber laser pumped by a 976 nm laser diode has been demonstrated at room temperature. Single-wavelength, dual-wavelength laser oscillations are observed when the fiber laser operates under different pump power by using different length of fibers. Stable dual-wavelength radiation around 1045 nm and 1075 nm has been generated simultaneously at a high pump power directly from an ytterbium-doped fiber laser without using any spectral control mechanism. A small core ytterbium-doped PCF fabricated by the powder sinter direction drawn rod technology is used as gain medium. The pump power and fiber length which can affect the output characteristics of dual-wavelength fiber laser are analyzed in the experiment. Experiments confirm that higher pump power and longer fiber length favors 1075 nm output; lower pump power and shorter fiber length favors 1045 nm output. Those results have a good reference in multi-wavelength fiber laser.

Optical properties of Tm^3+-doped microstructure fiber fabricated by plasma non-chemical vapor deposition

The optical properties and fabrication technology of Tm3+ doped microstructure fibers based on a new fabrication process of plasma non-chemical vapor deposition in our lab are detailedly analyzed.