This information dives deep into the advantages and exceptional properties of BBO crystal and its paramount importance in efficient frequency doubling and harmonics generation at 266nm.
The selection in the most suitable crystal material for a provided application is frequently significantly from trivial; it should really include the consideration of many facets. By way of example, a higher nonlinearity for frequency conversion of ultrashort pulses isn't going to enable If your interaction length is strongly constrained by a substantial group velocity mismatch and the small hurt threshold limits the relevant optical intensities.
These properties make BBO crystals highly appealing in numerous purposes, from laser frequency conversion to electro-optic modulation. Their extensive transparency selection permits them to operate having a broad selection of laser wavelengths, even though their significant injury threshold makes certain they can take care of substantial-power laser beams with out degradation.
The basic discipline now driving the kind-I SHG method may be the Eoγ component in the incident industry. At γ = 90°, there would be zero SHG output, Because the drive industry Eoγ = 0.
The Type-I section matching process relies on matching the standard and incredible indices of refraction for the elemental and second-harmonic frequencies, and that is obtained as a result of precise orientation of your crystal optic axis and enter propagation vector. A concentrated laser pulse, or beam, has angular content material, formally named spatial frequencies, to generate the small focal location.
A number of different phase-matching strategies can be employed to equalize the refractive indices of the elemental and 2nd harmonic mild. 1 strategy, which employs linearly polarized light-weight along with the distinction between the normal and extraordinary refractive indices, is Form-I crucial section matching. That is a widespread solution for adverse uniaxial crystals where no > ne.
The Rayleigh vary quantifies the space, measured in the beam waistline, in excess of which the beam diameter is about read more continuous. The shorter the Rayleigh selection, the bigger the rate of divergence.
The size of the crystal is an important parameter to think about when optimizing the SHG procedure with the parameters of distinct enter pulses. Absent stage-matching and temporal walk-off effects, the SHG output raises exponentially with crystal length. The aim when finding an SHG crystal is usually to harmony the crystal duration with the constraints based on the basic pulse. Decreasing the crystal thickness lessens outcomes related to both section-matching bandwidth restrictions and temporal wander-off, that happen to be straight relevant.
A5: Of course, BBO crystals have exceptional thermal security and may manage their Houses at area temperature. Therefore they are often Employed in a wide array of environments devoid of necessitating Specific temperature Regulate.
A: The broad transparency vary gives versatility, allowing BBO crystals for use throughout a diverse choice of wavelengths and applications.
Dust and stains on crystal surfaces might cause scattering/decline of light and may even react with light to wreck optical surfaces in a superior incident laser electrical power.
Although the examination benefits are only agent of one coating run, Thorlabs specifies harm threshold values that account for coating variances.
BBO crystals even have a superior harm threshold, indicating they are able to endure higher amounts of laser ability without suffering injury. This is particularly important in applications involving substantial-power lasers. Moreover, BBO crystals Use a superior nonlinear coefficient, which allows successful frequency conversion, a critical perform in lots of optical techniques.
The size from the SHG crystal drastically influences the spectral width of the reference pulse, or alternatively the bandwidth of the SHG filter.