a-BBO Crystal Secrets
a-BBO Crystal Secrets
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Nevertheless, in lots of conditions, the main difference in the basic and second harmonic pulse velocities could potentially cause a single pulse to appreciably lag the opposite.
A further equally intriguing application is optical parametric oscillation. With this, BBO permits the conversion of the photon into two photons with unique frequencies, the sum of which equals the initial photon’s frequency.
A: A large damage threshold assures the crystal can tackle extra electrical power with out degrading, leading to lengthier lifespan and steady efficiency.
The stage-matching capabilities of BBO crystals deserve Particular point out. Within the intricate dance of photons, where by conversion from 1 wavelength to another is often sought after, the stage-matching supplied by BBO makes certain that Electrical power losses are negligible.
Thorlabs expresses LIDT for CW lasers for a linear power density calculated in W/cm. During this routine, the LIDT supplied being a linear electrical power density can be placed on any beam diameter; one particular won't have to compute an altered LIDT to adjust for modifications in spot size, as demonstrated by the graph to the ideal. Average linear ability density is usually calculated utilizing the equation below.
Humidity could potentially cause h2o absorption over the crystal floor, which can degrade its optical general performance. The standard of the incident gentle, like its wavelength, intensity, and polarization, might also influence the efficiency of BBO crystals in various apps.
As illustrated in the following desk, the shorter the crystal, the broader the reference pulse spectrum. The table underneath assumes a elementary Heart wavelength inside the near-IR.
When pulse lengths are involving one ns and one µs, laser-induced harm can come about possibly thanks to absorption or simply a dielectric breakdown (hence, a consumer ought to Look at both CW and pulsed LIDT). Absorption is possibly as a consequence of an intrinsic assets with the optic or on account of floor irregularities; So LIDT values are only valid for optics Assembly or exceeding the area top quality specs presented by a maker.
A5: Certainly, BBO crystals have superb thermal balance here and may retain their properties at place temperature. Which means that they are often Utilized in a variety of environments without requiring Unique temperature Handle.
As will likely be talked over below, You will find there's focusing numerical aperture (NA) limitation for the SHG period-matching system particularly analogous for the spectral section matching limitation reviewed inside the prior portion (
For beams with a significant PRF the two the average and peak powers needs to be as compared to the equivalent CW electrical power. Moreover, for extremely clear components, there is very little to no drop inside the LIDT with increasing PRF.
The temporal walk-off is often regarded as extreme once the temporal lag exceeds the duration of the fundamental pulse. Serious walk-off may lead to temporal lag that irreparably enhances the length in the output second harmonic pulse.
The issue that arises when making use of ultrashort pulses for second harmonic technology (SHG) is usually that shorter pulses have larger bandwidths, but the ideal section-matched affliction might be attained For less than a single elementary wavelength at a time. Resulting from this, the caliber of the stage match is often substantially worse in the direction of the spectral edges of broad-bandwidth pulses.