@article{BoggioBodenmuellerFrembergetal.2014,
  author    = {Boggio, Jose M. Chavez and Bodenmueller, D. and Fremberg, T. and Haynes, R. and Roth, Martin M. and Eisermann, R. and Lisker, M. and Zimmermann, L. and Boehm, Michael},
  title     = {Dispersion engineered silicon nitride waveguides by geometrical and refractive-index optimization},
  series = {Journal of the Optical Society of America : B, Optical physics},
  volume    = {31},
  journal   = {Journal of the Optical Society of America : B, Optical physics},
  number    = {11},
  publisher = {Optical Society of America},
  address   = {Washington},
  issn      = {0740-3224},
  doi       = {10.1364/JOSAB.31.002846},
  pages     = {2846 -- 2857},
  year      = {2014},
  abstract  = {Dispersion engineering in silicon nitride (SiXNY) waveguides is investigated through the optimization of the waveguide transversal dimensions and refractive indices in a multicladding arrangement. Ultraflat dispersion of -84.0 +/- 0.5 ps/nm/km between 1700 and 2440 nm and 1.5 +/- 3 ps/nm/km between 1670 and 2500 nm is numerically demonstrated. It is shown that typical refractive index fluctuations as well as dimension fluctuations during fabrication of the SiXNY waveguides are a limitation for obtaining ultraflat dispersion profiles. Single- and multicladding waveguides are fabricated and their dispersion profiles measured (over nearly 1000 nm) using a low-coherence frequency domain interferometric technique. By appropriate thickness optimization, the zero-dispersion wavelength is tuned over a large spectral range in single-and multicladding waveguides with small refractive index contrast (3\%). A flat dispersion profile with +/- 3.2 ps/nm/km variation over 500 nm is obtained in a multicladding waveguide fabricated with a refractive index contrast of 37\%. Finally, we generate a nearly three-octave supercontinuum in this dispersion flattened multicladding SiXNY waveguide. (C) 2014 Optical Society of America},
  language  = {en}
}
@article{ZajnulinaBoggioBoehmetal.2015,
  author    = {Zajnulina, Marina and Boggio, Jose M. Chavez and B{\"o}hm, Michael and Rieznik, A. A. and Fremberg, Tino and Haynes, Roger and Roth, Martin M.},
  title     = {Generation of optical frequency combs via four-wave mixing processes for low- and medium-resolution astronomy},
  series = {Applied physics : B, Lasers and optics},
  volume    = {120},
  journal   = {Applied physics : B, Lasers and optics},
  number    = {1},
  publisher = {Springer},
  address   = {New York},
  issn      = {0946-2171},
  doi       = {10.1007/s00340-015-6121-1},
  pages     = {171 -- 184},
  year      = {2015},
  abstract  = {We investigate the generation of optical frequency combs through a cascade of four-wave mixing processes in nonlinear fibres with optimised parameters. The initial optical field consists of two continuous-wave lasers with frequency separation larger than 40 GHz (312.7 pm at 1531 nm). It propagates through three nonlinear fibres. The first fibre serves to pulse shape the initial sinusoidal-square pulse, while a strong pulse compression down to sub-100 fs takes place in the second fibre which is an amplifying erbium-doped fibre. The last stage is a low-dispersion highly nonlinear fibre where the frequency comb bandwidth is increased and the line intensity is equalised. We model this system using the generalised nonlinear Schrodinger equation and investigate it in terms of fibre lengths, fibre dispersion, laser frequency separation and input powers with the aim to minimise the frequency comb noise. With the support of the numerical results, a frequency comb is experimentally generated, first in the near infra-red and then it is frequency-doubled into the visible spectral range. Using a MUSE-type spectrograph, we evaluate the comb performance for astronomical wavelength calibration in terms of equidistancy of the comb lines and their stability.},
  language  = {en}
}