We report a first demonstration of two-photon endoscopic imaging with a lensless endoscope. The endoscope probe is a double-clad bundle of single-mode fibers; point excitation and scanning is achieved by coherent combining of femtosecond light pulses propagating in the single-mode fibers; and back-scattered two-photon signal is collected through the multi-mode inner cladding. We demonstrate the two-photon endoscope on a test sample of rhodamine 6G crystals.

We report the experimental demonstration of a modulation instability (MI) process assisted by a periodic dispersion modulation in an optical fiber. We observe the spontaneous growth of more than 10 pairs of MI sidebands spanning over more than 10 THz thanks to a quasi-phase-matched process.

We report a step toward scanning endomicroscopy without distal optics. The focusing of the beam at the distal end of a fiber bundle is achieved by imposing a parabolic phase profile across the exit face with the aid of a spatial light modulator. We achieve video-rate images by galvanometric scanning of the phase tilt at the proximal end. The approach is made possible by the bundle, designed to have very low coupling between cores.

In the present letter the authors report on the realization of an all-fiber bismuth-doped laser with laser emission that can be chosen with corresponding fiber Bragg gratings between at least 1150 and 1225nm. In their experiments they achieved a slope efficiency of about 24% at 1200nm, which is the highest reported for this kind of laser.

We report on the development of hollow-core photonic bandgap fibers for the delivery of high energy pulses for precision micromachining applications. Short pulses of (65ns pulse width) and energies of the order of 0.37mJ have been delivered in a single spatial mode through hollow-core photonic bandgap fibers at 1064nm using a high repetition rate (15kHz) Nd:YAG laser. The ultimate laser-induced damage threshold and practical limitations of current hollow-core fibers for the delivery of short optical pulses are discussed.

We describe a hollow-core photonic bandgap fiber designed for use in the 850 nm wavelength region. The fiber has a minimum attenuation of 180dB/km at 847nm wavelength. The low-loss mode has a quasi- Gaussian intensity profile. The group-velocity dispersion of this mode passes through zero around 830nm, and is anomalous for longer wavelengths. The polarization beat length varies from 4 mm to 13 mm across the band gap. We expect this fiber to be useful for delivery of high-energy ultrashort optical pulses.

An Ytterbium-doped photonic crystal fibre laser is demonstrated with a 100 microm2 core area and single transverse mode with an output efficiency of 30 %. Double-clad PCF laser structures are demonstrated with pump cladding NA greater than 0.8 and output power up to 3.9 W. Such lasers are potentially scalable to high power.

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