Changming Xia

Design and Analysis of a Microstructure Ring Fiber for Orbital Angular Momentum Transmission

In this paper, we propose a novel microstructure fiber with annular core for transmitting optical orbital angular momentum (OAM), and the OAM modes are calculated under different structure parameters of the fiber. Compared with the previous hollow step-index ring fiber, the proposed fiber brings higher refractive index contrast between the ring core and the cladding region by using only the single material of silica. The designed fiber can support more well-separated OAM modes with both thin and thick rings. Simulation results show that the novel microstructure ring fiber is promising to be applied in fiber-based OAM multiplexing in order to improve communication capacity.

A Surface Plasmon Biosensor Based on a D-Shaped Microstructured Optical Fiber With Rectangular Lattice

A numerical investigation of a surface plasmon biosensor based on D-shaped microstructured optical fiber (MOF) with rectangular lattice is presented. A full-vector finite-element method is applied to analyze the resonance coupling properties. By adjusting the diameters of two large air holes, the proposed biosensor shows excellent performance. High sensitivity and narrow full-width at half-maximum (FWHM) can be achieved. In particular, the figure of merit can reach to 478.3RIU-1, which is to our knowledge the highest among the reported MOF sensors. In the last part, the influence of coating thickness on the sensing performance has been considered.

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%.

Coherent Anti-Stokes Raman Scattering Microscopy by Dispersive Wave Generations in a Polarization Maintaining Photonic Crystal Fiber

The polarization maintaining photonic crystal flber (PM- PCF) with two zero dispersion wavelengths is designed and fabricated by the improved stack-and-draw technology in our laboratory. The broadband blue-shifted and red-shifted dispersive waves (DWs) are e-ciently generated from soliton self-frequency shift (SSFS) along the slow axis of PM-PCF. By optimizing the pump parameters and the flber length, the polarized DWs centered in the normal dispersion region can be used as the pump and Stokes pulses for the high resolution coherent anti-Stokes Raman scattering (CARS) microscopy. Moreover, it is demonstrated that the widely tunable relevant CARS wavelengths can be obtained by adjusting the pump wavelength. The CARS microscopy based on DWs can flnd important applications in detecting the biological and chemical samples with the C = N, S-H, C-H, and O-H stretch vibration resonances of 2100 to 2400cm i1 , 2500 to 2650cm i1 , 2700 to 3000cm i1 , and 3000 to 3750cm i1 .

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.

Widely tunable broadband deep-ultraviolet to visible wavelength generation by the cross phase modulation in a hollow-core photonic crystal fiber cladding

The deep-ultraviolet (UV) to visible wavelengths are efficiently generated for the first time by the cross phase modulation (XPM) between the red-shifted solitons and the blue-shifted dispersive waves (DWs) in the fundamental guided mode of the multi-knots of a hollow-core photonic crystal fiber cladding (HC-PCFC). When the femtosecond pulses with a wavelength of 850 nm and average power of 300 mW are coupled into the knots 1–3, the conversion efficiency ηuv−v of 11% and bandwidth Buv−v of 100 nm in the deep-UV region are experimentally obtained. The multi-milliwatt ultrashort pulses are tunable over the deep-UV (below 200 nm) to visible spectral region by adjusting the wavelengths of the pump pulses in different knots. It is expected that these widely tunable broadband ultrashort deep-UV–visible pulse sources could have important applications in ultrafast photonics, femtochemisty, photobiology, and UV–visible resonant Raman scattering.

Surface Plasmon Biosensor Based on a D-shaped Microstructured Optical Fiber with Rectangular Lattice

We investigate the coupling characteristics of two structures via finite element method (FEM). It indicates that the influence on sensor sensitivity caused by birefringence at d1=0.8and the polarization by embedded ethanol is almost similar.

Analysis of supermode and structural characteristics of octagonal multicore photonic crystal fiber with large effective mode area and low confinement loss

Abstract. An octagonal multicore photonic crystal fiber is proposed. The supermode and its far field distribution have been analyzed by using the full-vector finite element method. In the condition of in-phase supermode, the influences of different wavelengths, air filling fraction, and air hole diameter between cores on normalized intensity of cores are studied. The equal intensity distribution of cores in the output plane is realized. Finally, the effects of changing the air hole diameter between different cores on the effective mode area and confinement loss are investigated. The results show that the effective way to change the relative intensity between cores is to resize the air holes between different cores. If this parameter is changed, a better intensity distribution with large effective mode area and low confinement loss for propagation is obtained.

Degenerate Four-Wave Mixing-Based Light Source for CARS Microspectroscopy

A novel light source for coherent anti-Stokes Raman scattering (CARS) microspectroscopy based on degenerate four-wave mixing (DFWM) is experimentally demonstrated in a photonic crystal fiber with two adjacent zero dispersion wavelengths. When the pump pulse wavelengths are changed from 780 to 800 nm and the average input powers Pav are increased from 300 to 500 mW, the central wavelengths λas and λs of the generated anti-Stokes and Stokes waves are tunable from 660 to 606 nm and 953 to 1177 nm, respectively. In addition, the corresponding frequency difference between the pump and Stokes beams is in the range of 2331-4002 cm-1 , which covers a wide range of vibrational Raman spectra of the biological and chemical samples. The feasibility of the proposed DFWM-based light source is demonstrated through measuring the CARS spectrum of the ethanol sample.

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.