Beam intensity reshaping by pump modification in a laser amplifier

Abstract

We propose a new technique for laser beam shaping into a desirable beam profile by using a laser amplifier with a pump beam that has a modified intensity profile. We developed the analytical formula, which describes the transformation of the seed beam into the desired beam profile in a four level amplifiers small signal regime. We propose a numerically method to obtain the required pump intensity profile in the case where high pump power saturated the laser crystal or for three level materials. The theory was experimentally verified by one dimensionally shaping a Gaussian shaped seed into a Flat-Top beam in a Ho:YLF amplifier pumped by a Tm:YLF laser with a HG(01) intensity profile.

Controllable beam shaping of coherent and incoherent beams by a laser amplifier

“…In [10] the analytical equation for the correlation between the intensity profiles of the seed and the pump beams after the Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.…”

“…where δ = n max 2 /n tot is the ratio of the density of ions in the upper laser level to the total density of the ions, which cannot exceed 14%-16% [10]. The result of the simulation is presented in figure 1(a) and (b).…”

“…Based on a derivation of equation ( 1) [10], we can conclude that there would be no limitation with the coherency of the seed beam in the amplification process and therefore we were able to perform similar beam shaping with an incoherent seed beam. In order to prove the assumption, we replaced the coherent seed beam with an incoherent beam of the same wavelength.…”