Components for third harmonic of the Ti:Sapphire Laser

Components for the Third Harmonic of the Ti:Sapphire Laser

The third harmonic of the Ti:Sapphire laser provides fs - pulses in the UV range (∼250 – 330nm). These offer a variety of applications in spectroscopy as well as in materials science. Optics for these very special applications must be optimized for both high reflectivities and low dispersion. For more information about optics for the third and the higher harmonics please see our Components for the higher harmonic of Ti:Sapphire laser section or pages 70 – 71 of our catalog.

Dual Wavelength Mirrors

turning mirror for 270nm and 405nmFigure 1: Reflectance- (a) and GDD - spectra (b, c) of a fs - optimized turning mirror for 270nm + 405nm

Seperators for the Third Harmonic and the Ground Wave

separator HR 270nm and HT 405 + 810nmFigure 2: Reflectance- (a) and GDD - spectra (b) of a separator HR 270nm + HT 405 + 810nm (45°)
separators for the third and fourth harmonicsFigure 3:
Reflectance spectra of separators for the third and fourth harmonics:
HRr (45°, 266nm) > 98% + Rr (45°, 200nm) < 10%
a) oxide coatings optimized for low straylight losses (rear side uncoated )
b) flouride coatings for high laser induced damage thresholds and high transmission at 200nm (rear side uncoated)

Please note that aluminum oxide which is the high refractive index material for DUV oxide coatings exhibits absorption losses for wavelengths < 215nm, while fluoride coatings are free of absorption down to wavelengths as low as 140 nm.

Broadband Separators for the Third Harmonic

broadband separatorFigure 4: Reflectance (a) and GDD (b) spectra of a broadband separator with high reflectivity for s-polarized light throughout the wavelength range of the third harmonic of the Ti:Sapphire laser and high transmission for p-polarized light in the VIS and NIR: HRs(45°, 250 – 330nm) > 95% + Rp(45°, 440 – 1000nm) < 3%
broadband separatorFigure 5: Reflectance (a) and GDD (b) spectra of a broadband separator for normal incidence with high reflectivity throughout the wavelength range of the third harmonic of the Ti:Sapphire laser and high transmission in the VIS and NIR: HR(0°, 250 – 340nm) > 95% + R(0°, 600 – 900nm) < 10%

Separators with high reflectivity and low GDD in a broad wavelength range in the UV and high transmission in the VIS and NIR are still under investigation. In the following we present some sputtered coatings which meet these demands.