Bauteile für die dritte Harmonische der Nd:YAG und Nd:YVO4 Laser

The third harmonic of Nd:YAG and Nd:YVO₄ lasers has gained increasing importance in the field of materials processing as well as for measurement applications and as pump source for optical parametric oscillators. On these pages we introduce optics for 355nm: single and multiple wavelength mirrors, separators, thin film polarizers and anti reflection coatings. All designs are calculated according to customer specification.

Figure 1: Reflectance spectra of a single wavelength mirror for normal incidence (a) and of a turning mirror (b)

Figure 2: Reflectance spectra of a dual wavelength turning mirror for 355nm and 532nm (a) and of a tripel wavelength turning mirror for 355nm, 532nm and 1064nm (b)

Figure 3: Reflectance spectra of separators for the third harmonic from the second harmonic and the ground wavelength:
(a): standard type
(b): separator which is especially optimized for low reflectance at 1064nm

For common specifications of separators for the harmonics in the UV spectral range please see table on higher-harmonics. Please do not hesitate to contact us for separators or mirrors with other angles of incidence.

Figure 4: Reflectance spectra of special separators for the third harmonic from the second harmonic and the ground wavelength:
(a) Fluoridic Separator HR_s(45°, 355nm) > 95% + R_p(45°, 532nm) < 2% + R_s,p(45°, 1064nm) < 2%
(b) HR(45°, 532nm) > 99.8nm + R(45°, 355nm) < 5%

Fluoridic separators show an extended lifetime at high power densities. The transmission of the p-polarized light can be optimized by angle tuning. Tilting the polarizer by ± 2° shifts the minimum of Rp to longer or shorter wavelengths which can improve the polarization ratio significantly.

Figure 5: Reflectance spectra of a single wavelength AR coating for 355nm optimized for AOI = 0° – 30° (a) and of a triple wavelength antireflection coating on fused silica for 355nm, 532nm and 1064nm.

Figure 6: Reflectance spectrum of a thin film polarizer for 355nm: HR_s(55°, 355nm) > 99% + R_p(55°, 355nm) < 5%