The crystal axis is c. The chief ray is parallel on the direction utilized to measure the tuning angle (θ), that is optimized throughout phase matching. Conversion efficiency is optimized for rays parallel for the chief ray and even worse for rays at more substantial angles (ψ) to your Main ray.
This sort of resilience makes sure that its nonlinear Qualities are usually not quickly compromised, which makes it a favorite in environments wherever consistency and reliability are paramount.
So that you can use the required CW problems threshold of the optic, it is necessary to understand the next:
The phase matching angle is often adjusted by rotating the crystal round the y axis. An adjustment that is typically in just a couple of degrees can both enhance the functionality of your crystal from the setup or match Yet another fundamental frequency in the crystal's running assortment.
The Vitality density of your respective beam should be calculated with regard to J/cm2. The graph to the correct demonstrates why expressing the LIDT being an Vitality density presents the most effective metric for brief pulse sources. With this routine, the LIDT given as an energy density is usually applied to any beam diameter; a person won't ought to compute an altered LIDT to regulate for variations in spot measurement.
In the situation of Kind-I section matching and β-BBO crystals, the basic mild propagates as a unprecedented wave within the crystal, though the 2nd harmonic mild propagates as a normal wave.
Determine eighteen: The regular and incredible refractive indices of β-BBO vary with frequency and wavelength on account of a cloth home termed dispersion. Dispersion exists in all media besides vacuum.
The angular articles of a targeted beam is often visualized by tracing rays from your lens into the focal location. Every ray drawn from your lens into a tightly centered location (Determine 23) makes another angle (ψ) Together with the Main ray, as well as range of angles raises While using the NA. Since the number of angles improves beyond the reference NA filter (or angular domain apodization filter width), the stage-matching from the rays outside of the filter width diminishes for that reason lessening the SHG conversion performance of All those rays.
When pulse lengths are involving one ns and one µs, laser-induced problems can take place possibly due to absorption or even a dielectric breakdown (as a result, a user have to Test both of those CW and pulsed LIDT). Absorption is either as a result of an intrinsic house on the optic or as a consequence of surface irregularities; So more info LIDT values are only valid for optics Conference or exceeding the area good quality specifications offered by a company.
For that reason, the second harmonic pulse spectrum, revealed on the ideal, incorporates a spectral width roughly similar to the ideal circumstance. Ideally, every frequency in the basic pulse spectrum would be concurrently period matched.
This calculation assumes a uniform beam depth profile. You should now adjust this Vitality density to account for hotspots or other nonuniform depth profiles and roughly determine a utmost Electrical power density. For reference a Gaussian beam normally provides a maximum Vitality density that may be twice that with the 1/e2 beam.
Custom made coatings might be applied to the crystal surfaces to boost their functionality at precise wavelengths or to safeguard the crystal from environmental components. On the other hand, it’s imperative that you Observe that any customization need to be finished diligently to stay away from degrading the crystal’s optical Homes.
The temporal stroll-off is frequently deemed intense once the temporal lag exceeds the length of the fundamental pulse. Extreme wander-off can result in temporal lag that irreparably improves the period with the output second harmonic pulse.
BBO’s flexibility genuinely shines when 1 considers the breadth of its purposes. It’s not only confined to 1 specialized niche of photonics but stretches across various domains. Acquire frequency doubling, For example. In this process, photons with the same frequency Merge inside the crystal to generate new photons with double the frequency of the original.