The crystal axis is c. The Main ray is parallel into the direction used to measure the tuning angle (θ), that is optimized for the duration of stage matching. Conversion efficiency is optimized for rays parallel to the chief ray and even worse for rays at larger angles (ψ) for the Main ray.
However, in many scenarios, the difference in the basic and next harmonic pulse velocities can result in a person pulse to noticeably lag one other.
The place on the eco-friendly curve is dependent upon θ. In this case, the angle θ has become tuned to offer a refractive index for 515 nm gentle that matches the refractive index for 1030 nm light-weight. This tuning angle is thus optimized for Type-I SHG phase matching along with a basic-frequency enter beam of 1030 nm.
In quasi-stage matching, the crystal content is “poled�?to acquire up and down domains to counteract the stage-mismatch of the fabric, in which the poling time period is distinct on the wavelengths of interaction.
Finally, the wide-angle tunability of BBOs facilitates customization like never just before. With regards to the distinct needs of an software, the crystal is often adjusted with precision, making certain the output is often optimized.
In the case of Type-I section matching and β-BBO crystals, the elemental mild propagates as a unprecedented wave while in the crystal, when the 2nd harmonic mild propagates as a standard wave.
Even though the examination outcomes are only consultant of one coating operate, website Thorlabs specifies harm threshold values that account for coating variances.
Some companies' SHG crystals, together with Thorlabs', offer near-section-matched situations for Ordinarily incident enter mild for any specified fundamental frequency. These companies polish the faces with the SHG crystals such which the angle among the Usually incident light-weight plus the optic axis will be the phase-matched angle for the specified frequency.
This house sets it aside from linear optical supplies that don’t alter the frequency of sunshine passing through them. This type of distinguishing function kinds the inspiration for a plethora of programs that BBO can serve.
The team velocity is the speed of the pulse, or maybe more formally the envelope of the electric discipline. The team index similarly governs the speed with the envelope relative into the velocity of sunshine in the vacuum which is dependent on the dispersion of the material.
The two broad-bandwidth pulses and temporal wander-off cause a reduction while in the conversion efficiency, and worsen the optical high quality of the second harmonic pulses. The right crystal thickness really should be preferred to minimize equally outcomes.
The angular information with the resultant SHG pulse, or beam, while in the dimension of your angular filter is lessened from an excellent circumstance. From the perpendicular dimension, the SHG beam preserves the angular material of the enter beam, considering the fact that there’s no angular filter in that dimension. A diverging beam with asymmetric NA’s, i.e. within the horizontal and vertical Proportions, results in an elliptical beam.
When laser light-weight is targeted to some spot, the diameter of your beam midsection would be the focal spot dimensions, and the rate at which the light diverges from the beam midsection is connected to the Rayleigh array (zR).
This informative article dives deep into the benefits and distinctive Homes of BBO crystal and its paramount great importance in effective frequency doubling and harmonics era at 266nm.