Pr-doped YPO nanocrystal embedded into an optical fiber.

Optical fiber with YPO:Pr nanocrystals (NCs) is presented for the first time using the glass powder-NCs doping method. The method's advantage is separate preparation of NCs and glass to preserve luminescent and optical properties of NCs once they are incorporated into optical fiber. The YPO:Pr nanocrystals were synthesized by the co-precipitation and hydrothermal methods, optimized for size (< 100 nm), shape, Pr ions concentration (0.

Multimodal nonlinear endomicroscopic imaging probe using a double-core double-clad fiber and focus-combining micro-optical concept.

Multimodal non-linear microscopy combining coherent anti-Stokes Raman scattering, second harmonic generation, and two-photon excited fluorescence has proved to be a versatile and powerful tool enabling the label-free investigation of tissue structure, molecular composition, and correlation with function and disease status. For a routine medical application, the implementation of this approach into an in vivo imaging endoscope is required. However, this is a difficult task due to the requirements of a multicolour ultrashort laser delivery from a compact and robust laser source through a fiber with low losses and temporal synchronization, the efficient signal collection in epi-direction, the need for small-diameter but highly corrected endomicroobjectives of high numerical aperture and compact scanners.

Pre-compensation of thermally induced refractive index changes in a depressed core fully aperiodic large-pitch fiber for high average power operation.

To prevent the thermally induced spatial beam degradation occurring in high-power fiber lasers and amplifiers, index-depressed core "fully aperiodic large-pitch fibers" (FA-LPFs) have been designed and fabricated. In contrast to previous experimental works performed on FA-LPFs, in which the active core and the surrounding cladding material are quasi-index-matched, the core refractive index is in slight depression compared to the surrounding material (≈-3×10). Thus, the index-depressed fiber core tends first to behave as an anti-guide, preventing light from being properly guided into it.

Influence of pedestal diameter on mode instabilities in Yb/Ce/Al-doped fibers.

In this paper we present numerical and experimental results revealing that the mode instability threshold of highly Yb-doped, Ce/Al co-doped pedestal fibers is affected by the size of the index-increased pedestal structure surrounding the core. An alternative preparation technology for the realization of large mode area fibers with very large Al-doped silica pedestals is introduced. Three different pedestal fiber design iterations characterized by low photodarkening were manufactured and tested in counter-pumped amplifier setups.

Widely tunable Q-switched dual-wavelength synchronous-pulsed Tm-doped fiber laser emitting in the 2  μm region.

We demonstrate a widely tunable Q-switched dual-wavelength fiber laser emitting synchronized pulses in the 2 μm spectral range. Owing to the use of a Tm-doped rod-type fully aperiodic large pitch fiber, together with an acousto-optic modulator and two volume Bragg gratings (VBGs), the wavelength separation was shown to be continuously tunable from 1 to 120 nm (∼0.1-10  THz).