a-BBO Crystal Secrets
a-BBO Crystal Secrets
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The high injury threshold of BBO crystals is particularly critical in environments exactly where significant-intensity lasers tend to be the norm. Standard products could possibly falter, degrade, as well as split below these types of intensities.
Even so, in several cases, the real difference in the fundamental and 2nd harmonic pulse velocities may cause 1 pulse to significantly lag the opposite.
Figure 22: The diagram at the best shows two pulses with distinct Heart frequencies incident on a material. The team velocity hold off involving the pulses when they enter the material is zero.
Beam diameter can be important to know when comparing destruction thresholds. Even though the LIDT, when expressed in models of J/cm², scales independently of spot size; substantial beam sizes are more likely to illuminate a larger quantity of defects which can cause larger variances during the LIDT [four].
Any contamination can degrade the optical functionality of your crystal and perhaps trigger damage beneath substantial laser energy. When storing BBO crystals, they need to be placed in a very protecting situation to prevent Bodily problems and dust accumulation.
The performance from the SHG process decreases considerably as the fundamental beam diverges from its aim, Considering that the pulse Electricity is dispersed throughout a larger beam cross portion.
Their high destruction threshold and superb thermal balance make them suited to use in significant-electric power laser techniques, while their extensive transparency selection enables them to operate which has a wide range of laser wavelengths.
a-BBO crystals which has a wedge angle (α) can be custom fabricated with the specified orientation with the optical axis. A paired or such prisms While using the optical axes orthogonal to one another may be used to repeatedly modify the section shift or time hold off concerning two orthogonally polarized pulses.
Comprehension Crystal is akin to appreciating the bedrock of Sophisticated optical technological innovation. At its essence, BBO, or Beta Barium Borate, stands being a nonlinear optical crystal. The expression “nonlinear�?below signifies the one of a kind skill in the crystal to communicate with mild inside a method that alters the light’s frequency.
Fluorescence here excitation is yet another realm the place the 266nm generation showcases its importance. Fluorescence will involve the absorption of light by a material and the next emission of light at a different wavelength. The 266nm light-weight is very successful in remarkable certain fluorescent materials, creating them glow brightly and enabling for his or her detection and analyze.
The Uncooked supplies, ordinarily a combination of barium carbonate and boric acid, are positioned in a platinum crucible and heated until eventually they soften. The temperature is then gradually minimized, allowing for the BBO crystal to kind above a number of months. The crystal is then extracted, Reduce into the desired form, and polished to realize a higher-good quality optical floor.
For beams with a large PRF the two the standard and peak powers has to be in comparison with the equivalent CW electric power. Additionally, for really clear elements, There may be little to no fall while in the LIDT with growing PRF.
A advisable guideline for focusing femtosecond laser pulses right into a nonlinear crystal is to maintain a Rayleigh variety that is certainly at the very least many moments more time when compared to the length from the SHG crystal. This minimizes the chance of harming the crystal, together with lowers the unfavorable effects of spatial period mismatch and spatial (Poynting vector) walk-off.
Additionally, the structural and compositional attributes of BBO supply it with outstanding thermal stability and resistance versus environmental troubles.