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Optical radiation propagating in a fiber is used to deposit commercially available, single-walled carbon nanotubes on cleaved optical fiber end faces and fiber connectors. Thermophoresis caused by heating due to optical absorption is considered to be a likely candidate responsible for the deposition process. Single-walled carbon nanotubes have a fast saturable absorption over a broad wavelength range, and the demonstrated technique is an extremely simple and inexpensive method for making fiber-integrated, saturable absorbers for passive modelocking of fiber lasers. Pulse widths of 247 fs are demonstrated from an erbium-doped fiber laser operating at 1560 nm, and 137 fs pulses are demonstrated from an amplified Yb-doped fiber laser at 1070 nm.

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Recently introduced surface nanoscale axial photonics (SNAP) makes it possible to fabricate high-Q-factor microresonators and other photonic microdevices by dramatically small deformation of the optical fiber surface. To become a practical and robust technology, the SNAP platform requires methods enabling reproducible modification of the optical fiber radius at nanoscale. In this Letter, we demonstrate superaccurate fabrication of high-Q-factor microresonators by nanoscale modification of the optical fiber radius and refractive index using CO 2 laser and UV excimer laser beam exposures. The achieved fabrication accuracy is better than 2 Å in variation of the effective fiber radius. © 2011 Optical Society of America OCIS codes: 060.2340, 140.3945, 230.3990. Surface nanoscale axial photonics (SNAP) is concerned with microscopic optical devices created by smooth and dramatically small nanoscale variation of the optical fiber radius and/or equivalent variation of its refractive index [1,2]. SNAP is based on whispering gallery modes (WGMs), which slowly propagate along the fiber axis and circulate around its surface. Unlike slow light in photonic crystals, which is introduced with the periodic modulation of the refractive index [3], the slow axial propagation of light in SNAP is insured automatically by periodic revolution around the fiber surface. The direction of light propagation considered in SNAP is primarily azimuthal so that the axial propagation is naturally slow. There is both fundamental and applied interest in the development of SNAP. The SNAP devices are fabricated of drawn silica and, hence, exhibit very small losses and high Q factors, similar to those of silica WGM microresonators [4]. In addition, the characteristic axial wavelength of these devices is much greater than the wavelength of light, which makes them convenient for investigation of fundamental properties of light, e.g., tunneling, halting by a point source, and formation of dark states [1,2]. For the same reason, a large axial wavelength simplifies accurate fabrication of high-Q-factor microresonators and other microdevices at the surface of a fiber. Typically, the SNAP photonic elements have tens of micrometer dimensions and a record small attenuation of light with a Q factor in excess of 10 6 [1,2]. This suggests SNAP as a potential platform for miniature integrated photonic circuits having attenuation of light that is orders of magnitude smaller than that in microscopic devices fabricated with the existing photonic platforms [5][6][7].This Letter solves a challenging problem of accurate and reproducible modification of the optical fiber effective radius at nanoscale, which is critical for establishing of SNAP as a practical technology. We propose and demonstrate the fabrication of high-Q-factor SNAP microresonators (Fig. 1) based on IR (CO 2 laser) and UV (248 nm excimer laser) beam exposures.In our experiments, illustrated in Fig. 2, the local perturbations of the optical fiber shape and/or refractive index introduced by the IR and ...