Bauteile für Diodenlaser

Components for Diode Lasers

Diode lasers are widely used for measurement applications, as pilot lasers, for pumping of solid state lasers and for direct materials processing. Although diode lasers do not require external resonator optics and are mostly coupled to fibres, many applications require high quality beam steering optics such as beam combiners or scanning mirrors which are shown on the following pages. For more information on pump mirrors for solid state lasers and combiners for diode lasers please see Yb:YAG, NdYAG or on pages 52 — 64 of our catalog.

Turning Mirrors

broadband turning mirrorFigure 1: Reflectance spectra of a broadband turning mirror which can be used for all diode lasers between 808 and 980 nm (AOI = 45°, s- and p- polarization)

Scanning Mirrors

Broadband laser mirrorFigure 2: Reflectance spectra of a scanning mirror for diode lasers between 805 and 940 nm combined with R > 50 % between 630 and 670 nm (pilot laser): HRr (22–58°, 805 – 940 nm) > 99.3 % + Rr (22–58°, 630 – 670 nm) > 50 %

Thin Film Polarizer

  • Thin film polarizers are especially useful for polarization coupling of high power laser diodes
  • For high power 940 nm radiation we recommend to use Suprasil® 300, 3001 or 3002 as substrate material, because standard fused silica shows an absorption band around this wavelength
Broadband thin film polarizerFigure 3: Reflectance spectra of a broadband thin film polarizer for 940 – 970 nm: HRs(45°, 940 – 970 nm) > 99.9 %
+ Rp(45°, 940 – 970 nm) < 1 %

Conventional Steep Edge Combiners for Diode Lasers

  • At AOI = 22.5° the conventional steep edge filter separates 915 and 980 nm for p- and s- polarized and thus also for unpolarized light
  • To preserve the steep edge at AOI = 45° the radiation must be polarized and only one polarization can be used. Unpolarized light changes the slope of the edge significantly.
Conventional steep edge filterFigure 4: Transmittance spectra of a conventional steep edge filter HR(980 nm) > 99.9 % and HT(915 nm) > 95 % which is used as combiner for pump laser diodes at 915 and 980 nm
  • AOI = 22.5° (a) and
  • AOI = 45° (b)

Special Steep Edge Combiners for Unpolarized Light

  • Filters of this type can be used as separators or combiners for s- and p- polarized light even at 45° incidence
  • The cut on / cut off edges for the two polarizations show only a spectral distance of about 10 nm
  • Consequently, these filters can be applied as combiners for unpolarized light of 940 and 980 nm diodes at AOI = 45°
special steep edge filterFigure 5: Transmittance spectra of a special steep edge filter HRu(45°, 980 nm) > 99.8 % + HTu(45°, 940 nm) > 97 %