Gratings for High Power Lasers

Chirped-pulse amplification (CPA) laser systems suffer from pre-pulse effects, which affects the spectral range and contrast. This pre-pulse is a region of noise which is able to interact with the target prior to the main pulse and this can be detrimental. STFC’s patented technology allows CPA systems to produce pedestal free, enhanced contrast pulses.

 

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DESCRIPTION

Chirped pulse amplification (CPA) is a technique for amplifying an ultrashort laser pulse up to the petawatt level. The laser pulse is stretched out to many thousand times its original length in a pulse stretcher prior to amplification (Figure 1). This is to avoid the extreme intensities that would occur if the pulse were amplified directly, as these intensities would damage or destroy optical components of the laser. The pulse is re-compressed to close to its original length following amplification and then focused on a target. The combination of stretching and compression must preserve the shape and duration of the original pulse as much as possible.

 

Experimentally in every high-energy short pulse laser, the re-compressed pulse is surrounded by a region of noise named the pedestal (or pre-pulse) in which the intensity of light is far higher than necessary for the short pulse to interact with an undisturbed target. STFC’s laser facility has developed an innovative method to remove this region of noise, by using a pulse stretcher made entirely of all-transmission gratings. The advantages of this system over reflective gratings is shorter pulse (reduced pre-pulse); broader spectral range; improved contrast ratio.

 

ADVANTAGES

 

•       Simple implementation

•       An order of magnitude improvement in the contrast pedestal

 

APPLICATION AREAS

 

•       Research equipment and facilities

•       Laser material processing

•       Laser surface ablation

•       Medical lasers

 

Patent Information:
Country Serial No.
United Kingdom 1404801.1
United States US 15/126,403
European Patent Office EP15709336.0
For Information, Contact:
Liam Brennan
STFC Innovations
liam.brennan@stfc.ac.uk
Keywords:
05.f. Physics