BBO Crystal for Dummies
BBO Crystal for Dummies
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Non-linear Optical (NLO) crystals provide an enormously versatile solution for making new wavelengths from existing, off-the-shelf laser resources. The optical wavelength spectrum is utilized by a substantial and continually expanding selection of programs, from manufacturing of clinical lasers, quantum networking & computing by to environmental sensing as well as many Other people.
The 2 frequencies' stage velocities are equal whenever they possess the very same refractive index. The refractive indices for both of these frequencies are commonly not equivalent, due to the fact all media other than vacuum are dispersive. Which means that a material's refractive index is dependent upon The sunshine's frequency.
Thorlabs provides a good selection of optics optimized for use with femtosecond and picosecond laser pulses. Make sure you see underneath To find out more.
Of course, BBO crystals may be personalized to fulfill particular demands. This involves tailor made dimensions, styles, and coatings. Tailor made sizes and shapes might be Lower to suit distinct optical units, although customized coatings may be applied to improve the crystal’s functionality in particular purposes.
The kind-I section matching method relies on matching the normal and incredible indices of refraction for the fundamental and 2nd-harmonic frequencies, which happens to be attained through exact orientation with the crystal optic axis and input propagation vector. A targeted laser pulse, or beam, has angular content, formally called spatial frequencies, to generate the small focal place.
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There's two velocities that outline the propagation of light in optical media: the stage and team velocities. The section velocity will be the pace of your provider, the oscillation of the electric subject, plus the velocity that is definitely matched concerning the fundamental and second harmonic frequencies for section matching. The phase velocity relative towards the pace of light in the vacuum is described with the index of refraction.
Nonlinear Crystals of possibly β-barium borate (BBO) or lithium triborate (LBO) are employed for frequency conversion of laser resources. BBO crystals function thicknesses from 0.2mm to 0.5mm to minimize team velocity mismatch and are perfect for frequency doubling or tripling of Ti:Sapphire and Yb:doped laser pulses. The crucial and noncritical section matching LBO crystals are perfect for 2nd or third harmonic generation of Nd:YAG and Yb:doped lasers.
In summation, though a lot of crystals present certain advantages while in the realm of photonics, BBO crystals arise as thorough powerhouses. They encapsulate A selection of attributes that are not just valuable in isolation but perform synergistically, making a holistic solution for frequency doubling and harmonics generation.
Because the dynamics of this method are hugely subject matter to experimental parameters, it is actually difficult to arbitrarily forecast the specific effects on the 2nd harmonic pulse. These outcomes can include things like back again conversion, where next harmonic light-weight is transformed again to essential gentle, and spectral narrowing on the SHG pulse.
Pumped from the fourth harmonic of the Nd:YAG laser (at 266nm), a tunable OPO with sign wavelength array in between 422nm and 477nm is noticed by angle-tuning a type I BBO crystal. Pumped by a 1mJ, 80fs Dye laser at 615nm, the OPA with two BBO crystals yields more than fiftyµJ (utmost one hundred thirtyµJ),
A number of Homes of a nonlinear crystal can be vital for an software e.g. in nonlinear frequency conversion:
BBO crystals should be dealt with with treatment to prevent scratching or detrimental their surfaces. They need to be saved in a dry, amazing put and stored faraway from immediate sunlight. Typical cleansing which has a comfortable fabric or air blower is usually recommended to maintain their optical functionality. When managing BBO crystals, it’s crucial to use gloves to stop oils through the pores and skin from contaminating the crystal floor.
Because the refractive index isn't going get more info to vary linearly with frequency in dispersive crystals like β-BBO, it truly is impossible to optimally phase match every single frequency in the input pulse's spectral array with the corresponding 2nd harmonic frequency from the created pulse.