Photonic Jet-Shaped Optical Fiber Tips versus Lensed Fibers

Shaped optical fiber tips have recently attracted a lot of interest for photonic jet light focusing due to their easy manipulation to scan a sample. However, lensed optical fibers are not new. This study analyzes how fiber tip parameters can be used to control focusing properties. Our study shows that the configurations to generate a photonic jet (PJ) can clearly be distinguished from more classical-lensed fibers focusing. PJ is a highly concentrated, propagative light beam, with a full width at half maximum (FWHM) that can be lower than the diffraction limit. According to the simulations, the PJs are obtained when light is coupled in the guide fundamental mode and when the base diameter of the microlens is close to the core diameter. For single mode fibers or fibers with a low number of modes, long tips with a relatively sharp shape achieve PJ with smaller widths. On the contrary, when the base diameter of the microlens is larger than the fiber core, the focus point tends to move away from the external surface of the fiber and has a larger width. In other words, the optical system (fiber/microlens) behaves in this case like a classical-lensed fiber with a larger focus spot size. The results of this study can be used as guidelines for the tailored fabrication of shaped optical fiber tips according to the targeted application.

Design and performance of bending-magnet beamline BL02B at the SSRF

The BL02B bending-magnet beamline at the Shanghai Synchrotron Radiation Facility (SSRF) has been constructed and is now operational for ambient-pressure photoelectron spectroscopy (APPES) and photon-in/photon-out spectroscopy (PIPOS) experimental use. Optical optimization was implemented for realization of high performance, e.g. photon flux, energy-resolving power and focus spot size. X-ray photoelectron spectroscopy experiments show that the energy range extends from 40 to 2000 eV. Argon, nitrogen and neon gas core-shell excitation spectra indicate energy-resolving powers of over 1.4 × 104 @ 244 eV, 1.0 × 104 @ 401 eV and 7.0 × 103 @ 867 eV, respectively. The measured photon flux is 1.3 × 1011 photons s−1 @ E/ΔE = 3700 at 244 eV at the expected sample position, for the SSRF electron energy of 3.5 GeV and electron current of 240 mA. The spot sizes are 177 µm × 23 µm and 150 µm × 46 µm at the APPES and PIPOS samples, respectively.

Research on fiber coupling technology of kilowatt laser diode by single emitters

This paper proposes a program that combine the laser of single-emitters by using fiber combiner, what’s more, we designed and developed a multiple single emitters diode laser module of full optical fiber. We used ZEMAX software to simulate and optimize the influence of fiber coupling efficiency by the location of cylindrical lens and fiber, finally, we developed 8W fiber coupling single emitter diode laser, the wavelength is 915nm, fiber diameter is 105/125μm, NA0.15. This article also carried on the theoretical research of N×1 fiber combiner, and based on Vytran GPX glass processing system, we fabricated the 19×1fiber combiner by TFB technique, combined 19 105/122μm, NA0.15 fibers to a 400/440μm, NA0.22 fiber, has realized 150W laser output, with fiber combining efficiency more than 96%. In the end, 8*400um fibers are synthesized through a fiber taper. The output laser power after fiber taper reached 1453W, with the focus spot size is 2.25mm*1.1mm and power density reached 6×104W/cm2.