Optics for fs-lasers in the 1100-1600nm wavelength range

Optics for Femtosecond Lasers in the 1100-1600nm Wavelength Range

Although Ti:Sapphire lasers are at present the most important femtosecond lasers many applications require femtosecond pulses at considerably longer wavelengths. Several lasers emitting light between 1100 nm and 1600 nm have been developed in the recent years, such as the Cr : Forsterite laser (1150 – 1350 nm) or the Er : Fibre laser (1550 nm). Here we present some examples of coatings – negative dispersion mirrors and mirror pairs, cavity and turning mirrors – which are intended to show our capabilities also for femtosecond laser optics in this spectral region.

Special Features:
  • Very high reflectivity of the mirrors (R > 99.8 % … R > 99.95 % depending on the design)
  • Centre wavelength, bandwidth, GDD and TOD according to customer specification
  • Spectral tolerance 1% of centre wavelength
  • LIDT ∼ 0.1 J/cm2
  • In house design calculation capabilities

Negative Dispersion Laser and Pump Mirrors

Laser Mirror with negative dispersion
Figure 1:  Reflectance (a) and GDD (b) spectrum of a negative dispersion laser mirror
(GDD∼ –150 fs2 for 1200 – 1370 nm)
Pump Mirror with negative dispersion
Figure 2:  Reflectance (a) and GDD (b) spectrum of a negative dispersion pump mirror:
HR(0°, 1180 –1380nm) > 99.8% + R(0°, 1020 –1070nm) < 5%, GDD (1180 – 1380nm) ∼ – 60 fs2

Broadband Negative Dispersion Mirror Pairs

Laser Mirror with negative dispersion
Figure 3:  Reflectance (a) and GDD (b) spectra of a broadband negative dispersion mirror pair;
single mirrors with R > 99.7 % (mirror 1) and R > 99.85 % (mirror 2)

Especially designed mirror pairs show a very smooth average GDD spectrum, although the single broadband mirrors exhibit strong GDD oscillations. Pump mirror pairs (i. e. mirror pairs with one mirror showing high transmission at the pump wavelength of the respective laser type) are also possible.

Broadband Negative Dispersion Turning Mirrors

Laser Mirror with negative dispersion
Figure 4:  Please note the large bandwidth of this mirror. Low dispersion turning mirrors are available with bandwidths of about 200 nm for p - polarization and of about 400 nm for s - polarization in this wavelength range.

Please note the large bandwidth of this mirror. Low dispersion turning mirrors are available with bandwidths of about 200 nm for p - polarization and of about 400 nm for s - polarization in this wavelength range.