No abstract

We successfully realized broad-band light-emitting color center waveguides buried in LiF crystals by using femtosecond laser pulses. The characterization of the waveguides was performed by optical microscopy, photoluminescence spectra, loss measurements and near-field profiling. The experimental results show that the direct-writing fabrication process induces low-index contrast active channel waveguides: their wavelength-dependent refractive index changes, estimated from 10(-3) to 10(-4) depending on the writing conditions, allow supporting few modes at visible and near-infrared wavelengths. (C) 2014 AIP Publishing LLC

Fiber gratings are among key components in fiber-based photonics systems and, particularly, laser cavities. In the latter, they can play multiple roles, such as those of mirrors, polarizers, filters, or dispersion compensators. In this Letter, we present the inscription of highly reflective first-order fiber Bragg gratings (FBGs) in soft indium fluoride-based ( I n F 3 ) fibers using a two-beam phase-mask interferometer and a femtosecond laser. We demonstrate an enhanced response of I n F 3 -based fiber to a visible (400 nm) inscription wavelength compared to ultraviolet irradiation at 266 nm. In this way, FBGs with a reflectivity > 99.7 % were inscribed at around 1.9 µm with the bandwidth of 2.68 nm. After thermal annealing at 393K, the Bragg wavelength demonstrates stable thermal shift of 20 pm/K in the temperature range 293–373K. These observations suggest a potential extension of I n F 3 fiber-based laser components to an operational range of up to 5 µm.

Broadband waveguiding through light-emitting strips directly written in a blank lithium fluoride crystal with a femtosecond laser is reported. Light guiding was observed at several optical wavelengths, from blue, 458 nm, to near-infrared, at 1550 nm. Visible photoluminescence spectra of the optically active F2 and F + 3 color centers produced by the fs laser writing process were measured. The wavelength-dependent refractive index increase was estimated to be in the order of 10 −3 -10 −4 in the visible and near-infrared spectral intervals, which is consistent with the stable formation of point defects in LiF.