We report the fabrication of single mode buried channel waveguides for the whole mid-infrared transparency range of chalcogenide sulphide glasses (λ ≤ 11 µm), by means of direct laser writing. We have explored the potential of this technology by fabricating a prototype three-dimensional three-beam combiner for future application in stellar interferometry, which delivers a monochromatic interference visibility of 99.89% at 10.6 µm, and an ultrahigh bandwidth (3-11 µm) interference visibility of 21.3%. These results demonstrate that it is possible to harness the whole transparency range offered by chalcogenide glasses on a single on-chip instrument by means of direct laser writing, a finding that may be of key significance in future technologies such as astrophotonics and biochemical sensing. . An essential step in order to unleash all of this potential science is to develop integrated optical platforms capable of addressing the technological requirements that each field demands. In this sense, the development of on-chip instruments such as optical sensors, high resolution spectrometers, or sophisticated beam combiners, is currently of high interest for the previous mentioned applications [1,2,5,6,7].Although several MIR two-dimensional (2D) planar schemes have been recently developed [8,9], these are all based on multiple-step surface deposition and processing techniques, which place inherent limits to the device design and capabilities. In this Letter, we report the single-step fabrication of three-dimensional (3D) MIR photonic circuits inside chalcogenide glass, by means of ultrashort-pulse direct laser writing (DLW) [10][11][12][13][14]. We show that the MIR waveguide cores can be tailored in both size and refractive index, and can also be spatially positioned at will inside the material, making the chip extremely robust against mechanical stress, vibrations, humidity, and temperature changes [11]. Moreover, we also evidence that the useful range of these DLW waveguides is, as suspected [12], ultimately limited by the transparency range of the material used, and not by the fabrication technique.In this work, high quality research and commercial chalcogenide sulphide glasses were used, both of which are free of highly toxic arsenic compounds. These glasses were commercial GaLaS (here after GLS) [14] and the research composition 75GeS2-15Ga2S3-4CsI-2Sb2S3-4SnS (here after GCIS) [15]. The MIR transmission upper limit of commercial GLS is known to be ~10 µm [14], while for GCIS we measured a slightly higher transmission upper limit of ~11 µm, as it is shown in Figure 1(a).

Optical waveguides have been inscribed in periodically poled lithium niobate by femtosecond laser pulses with the multiscan technique. Second harmonic generation experiments from a fundamental wavelength of 1567nm demonstrate that the nonlinear optical coefficient in the waveguides is preserved, yielding a conversion efficiency of 18%W−1.

A fan-out device has been fabricated using ultrafast-laser waveguide-inscription that enables each core of a multicore optical fiber (MCF) to be addressed by a single mode fiber held in a fiber V-groove array (FVA). By utilizing the unique three-dimensional fabrication capability of this technique we demonstrate coupling between an FVA consisting of a one-dimensional array of fibers and an MCF consisting of a two-dimensional array of cores. When coupled to all cores of the MCF simultaneously, the average insertion loss per core was 5.0 dB in the 1.55 mum spectral region. Furthermore, the fan-out exhibited low cross-talk and low polarization dependent loss.

Ultrafast laser inscription is used to fabricate the gain element for a mode-locked Er-doped bismuthate glass waveguide laser. Mode-locking is initiated and stabilized by the use of a single wall carbon nanotube saturable absorber. The waveguide laser produces 320 fs pulses at 1.56 m with a pulse repetition rate of 40 MHz and average output power of 1.25 mW.