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Bauteile für schwache Nd:YAG oder Nd:YVO4 Laser

Neodymium doped crystals show laser transitions at different wavelengths. Table 1 gives an overview about the laser wavelengths of the most common Nd doped materials Nd:YAG and Nd:YVO₄.

Nd:YAG		Nd:YVO₄
Laser line	Second harmonic	Laser lines	Second harmonic
946 nm	473 nm	915 nm	457 nm
1064 nm	532 nm	1064 nm	532 nm
1123 nm	561 nm
1319 nm	659 nm	1340 nm	670 nm

Table 1:

Laser lines and corresponding wavelengths of the second harmonic of Nd:YAG and Nd:YVO₄

As can be seen, a variety of laser lines in the VIS and NIR can be obtained from these crystals. This phenomenon is used to build compact diode pumped solid stated lasers with a variety of wavelengths which are used for measurement applications as well as for projection systems (RGB lasers).

The strongest laser transition in both materials is the 1064nm line. Efficient laser radiation at the other wavelengths is only possible by suppressing this line. LAYERTEC offers a variety of laser mirrors for this application.

Compact laser designs include also the pump diode (808nm) and a unit for the second harmonic generation. This is the reason, why coatings for Nd:YAG or Nd:YVO₄ wavelengths apart from 1064nm mostly show several spectral regions of high transmission as well as of high reflection. In the following we present some examples of such coatings. All coatings are designed according to customer specifications, because the specifications depend on the laser design. All examples on these pages are for Nd:YAG wavelengths. Coatings for Nd:YVO₄ can be designed and produced as well.

Feature	Reflectivity
Suppression of the strongest laser line	R(0°, 1064 nm) < 5 %
HR mirror for the weak laser line	R(0°, 946 nm) > 99.95 %
Higher transmission for the pump wavelength	R(0°, 808 nm) < 2 %
HR mirror for the second harmonic of the weak laser line	HR(0°, 473 nm) > 99.85 %

Figure 1: Reflectance spectrum of a dual wavelength mirror for a weak laser line and its second harmonic with high transmission for the pump wavelength and the strongest laser line:
HR(0°, 473nm) > 99.85% + HR(0°, 946nm) > 99.95% + R(0°, 808nm) < 2% + R(0°, 1064nm) < 5%

Feature	Reflectivity
HR mirror for the weak laser line	HR(0°, 1123 nm) > 99.9 %
Suppression of the strongest laser line	R(0°, 1064 nm) < 50 %
High transmission for the pump wavelength	R(0°, 808 nm) < 10 %
High transmission for the second harmonic of the weak laser line	R(0°, 561 nm) < 2 %

Figure 2: Reflectance spectrum of a dichroic mirror with high transmission for the pump wavelength which also suppresses the 1064nm line:
HR(0°, 1123nm) > 99.9% + R(0°, 561nm) < 2% + R(0°, 808nm) < 10% + R(0°, 1064nm) < 50%

Feature	Reflectivity
HR for s-polarized light of the weak laser line	HR_s(56°, 1123 nm) > 99.9 %
Suppression of p-polarized light of the weak laser line	R_p(56°, 1123 nm) < 50 %
Suppression of the strongest laser line	R_{s + p}(56°, 1064 nm) < 50 %
High transmission for the pump wavelength	R_{s + p}(56°, 808 nm) < 10 %
High transmission for the second harmonic of the weak laser line	R_{s + p}(56°, 561 nm) < 10 %

Figure 3: Reflectance spectra of a thin film polarizer with high transmission for the pump wavelength and the second harmonic which also suppresses the 1064nm line:
HR_s(56°, 1123nm) > 99.9% + R_p(56°, 1123nm) < 50% + R_s,p (56°, 561+808nm) < 10% + R_s,p(56°,1064nm) < 50%

Feature	Reflectivity
Broadband HR mirror for several laser lines	HR(0°, 1064 + 1123 + 1319 nm) > 99.9 %
High transmission for the second harmonics of these laser lines	R(0°, 532 - 561 + 659 nm) < 2 %

Figure 4: Reflectance spectrum of a dichroic mirror with high reflectance for the NIR wavelengths and high transmission for the corresponding second harmonic wavelengths:
HR(0°, 1064 + 1123 + 1319nm) > 99.9% + R(0°, 532–561+659nm) < 2%