Gires-Tournois-Interferometer (GTI) Mirrors

Gires-Tournois-Interferometer (GTI) Mirrors

Gires-Tournois-Interferometer mirrors are used for pulse compression in femtosecond lasers such as Yb:YAG - or Yb: KGW- lasers. LAYERTEC offers GTI mirrors also for the Ti:Sapphire wavelength range and for wavelengths up to 1600nm. Compared to prism compressors GTI mirrors reduce the intra-cavity losses resulting in higher output power of the laser.

GTI-Mirrors for the Ti:Sapphire Wavelength Range

GTI Mirror PairFigure 1: Reflectance (a) and GDD (b) spectra of a pair of GTI - mirrors for 780 – 840 nm (single mirrors: GDD = –160 ± 20 fs2, mirror pair: GDD = –160 ± 10 fs2)

The mirror pair shows a very smooth average GDD spectrum, although the single mirrors exhibit considerable GDD oscillations.

GTI-Mirrors for Yb:YAG and Yb:KGW Lasers

GTI Mirror PairFigure 2: GDD spectra of GTI-mirrors for 1030nm with different GDD values (a), of a GTI-mirror with nearly constant
TOD (b) and comparison of measured and calculated GDD spectra of a GTI mirror with GDD –500fs2 (c)

Measured and calculated GDD - curves match very well which proves the reliability of the coating process.

GIT-Mirrors for other Femtosecond Lasers

GTI Mirror PairFigure 3: Reflectance (a) and GDD spectra (b) of GTI mirrors for 1130 nm with different GDD values
GTI Mirror PairFigure 4: Reflectance (a) and GDD spectra (b) of GTI mirrors for 1500 nm with different GDD values

Special Features:

  • GDD between – 200fs2 and –2000fs2
  • Very high reflectivity
  • Measured LIDT 0.1 J/cm2
  • Centre wavelength, bandwidth and GDD according to customer specification.
    Please note that bandwidth and GDD are closely connected. A high value of negative GDD results in a very narrow bandwidth.
  • Spectral tolerance 1% of centre wavelength
    GTI - mirrors with a GDD up to –500 fs2 are designed for a bandwidth of λ > 20 nm and will meet the specification even if the centre wavelength is 1% apart from the design wavelength. At higher GDD-values it is favourable to design the laser so that the GTI - mirror can be tilted by ± 10° to adjust the mirror for its best performance.
  • In house design calculation and measurement capabilities (GDD 250 – 1700 nm, R-measurement by CRD at several wavelengths in the VIS and NIR)