Fabrication and characterization of continuous wave direct UV (λ=244 nm) written channel waveguides in chalcogenide (Ga:La:S) glass

In situ assessment and minimization of nonlinear propagation effects for femtosecond-laser waveguide writing in dielectrics

“…Insertion losses were determined by measuring the output power of the waveguide coupled to a standard telecom fiber and comparing this value with the output power of the fiber itself at 1440 nm, in order to avoid Er 3+ ion absorption at 1550 nm. Coupling losses were then estimated by calculating the spatial overlap integrals of the guided mode of the fiber and that of the waveguide, according to [32]. In this way, by subtracting the coupling losses from the total insertion loss, and once Fresnel losses are computed, an upper limit of the propagation loss is obtained, as no extrinsic losses are taken into account such as longitudinal, transversal, or angular displacements.…”

Femtosecond-Laser Microstructuring of Ribs on Active (Yb,Nb):RTP/RTP Planar Waveguides

“…Some corrections had to be made to both powers ( and ). The estimation of the propagation losses has to consider though some corrections to the values of and like the transmission losses of the microscope objectives, the Fresnel losses at the waveguide interfaces, the losses associated to the mismatch between the laser field distribution at the focal plane of the lens and the mode of the waveguide (calculated through the corresponding overlapping integral [23]). Since we have not corrected the losses associated to the effect of the different numerical apertures of the waveguide and the input microscope objective and the losses associated to the absorption of the beam by the small amount of Yb present in the waveguide, the estimated value of the propagation loss have to be considered as an exaggerated upper bound.…”

Direct UV-Written Integrated Optical Beam Combiner for Stellar Interferometry

“…Chalcogenide fibers guiding at 10 µm have been studied for astronomical applications [15], while a recent experiment at the Keck telescopes [16] showed the possibility to use fluoride fibers to extend the interferometer capability up to 2.2 µm. On the other hand, direct UV writing has been demonstrated both in chalcogenide [17] and fluoride glasses [18]. Therefore, it is possible, in principle, to reproduce our UV-written IO beam combiner in a new material with wider wavelengthoperation range.…”