Lasers beams with a specific intensity profile such as super-Gaussian, Airy or Dougnut-like are desirable in many applications such as laser materials processing, medicine and communications. We propose a new technique for laser beam shaping by amplifying a beam in an end-pumped bulk amplifier that is pumped with a beam that has a modified intensity profile. Advantages of this method are that it is relatively easy to implement, has the ability to reshape multimode beams and is naturally suited to high power/energy beams. Both three and four level gain materials can be used as amplifier media. However, a big advantage of using three level materials is their ability to attenuate of the seed beam, which enhances the contrast of the shaping.
We first developed a numerical method to obtain the required pump intensity for an arbitrary beam transformation. This method was subsequently experimentally verified using a three level system. The output of a 2.07 mu m seed laser was amplified in a Ho: YLF bulk amplifier which was being pumped by a 1.89 mu m Tm:YLF laser which had roughly a TEM10 Hermit Gaussian intensity profile. The seed beam was amplified from 0.3 W to 0.55 W at the full pump power of 35 W. More importantly, the beam profile in one transverse direction was significantly shaped from Gaussian to roughly flat-top, as the model predicted. The concept has therefore been shown to be viable and can be used to optimise the beam profile for a wide range of applications.
|Title of host publication||Laser Resonators, Microresonators, and Beam Control XVII|
|Editors||AV Kudryashov, AH Paxton, VS Ilchenko, L Aschke, K Washio|
|Place of Publication||Bellingham|
|Number of pages||6|
|Publication status||Published - 2015|
|Event||Conference on Laser Resonators, Microresonators, and Beam Control XVII - San Francisco, Canada|
Duration: 9 Feb 2015 → 12 Feb 2015
|Name||Proceedings of SPIE|
|Publisher||SPIE-INT SOC OPTICAL ENGINEERING|
|Conference||Conference on Laser Resonators, Microresonators, and Beam Control XVII|
|Period||9/02/15 → 12/02/15|
- Beam shaping
- Ho: YLF