![]() ![]() Due to the low quantum defect, the amplitude of the electronic component becomes comparable for all three materials and, in the case of Yb:CaF2, almost completely compensates the thermal component resulting from a pump pulse during the time frame of laser pulse amplification. These contributions were individually determined by a COMSOL-based thermal profile model along with a detailed characterization of the electronic changes by measuring the single-pass gain and the spatial fluorescence profile. Time-resolved interferometric measurements were performed to reveal the profiles of the total optical path differences (OPDs), which are described by the spatio-temporal superposition of thermal as well as electronic contributions, across the free aperture of the considered diode-pumped active materials. The amplifier has been successfully employed in a 200 Hz, 5 J, MOPA system with 1.7 times diffraction limited output.Ī comprehensive spatio-temporal characterization is presented describing the pump-induced wavefront aberrations in Yb3 + -doped YAG, CaF2, and fluorophosphate glass. For a repetition frequency of 200 Hz, 25 μJ injection polarized seed-light and 1440 W pump power, the small signal gain reaches 9.45. In the amplifier, the fluorescence is uniformly distributed and the maximum stored energy of 3.2 J can be achieved with a plane-concave cavity at 200 Hz pump repetition frequency. The fluorescence distribution, stored energy, and small-signal gain of the amplifier are measured and have a good agreement with the calculated results. The amplifier shows stable aberration character with two major low-order terms, defocus and 0° astigmatism. Under the 200 Hz, 1440 W pulse pumping condition while no seed light to amplify, the thermal induced wavefront aberration of a He-Ne probe passing through the gain meUdium is 0.165 nm (RMS). This architecture makes efficient use of the transverse beam filtering inherent in the active medium to deliver a beam with excellent quality (TEM00) without additional losses.Ī high gain, low thermal-induced wavefront distortion, laser diode-pumped Nd: YAG slab amplifier is demonstrated with its active media dimensions of 7 mm×35 mm×138.2 mm. The dependence of the output beam divergence and size is investigated also for variations of the number of passes, for aperture effects in the active medium and as a function of the size of the beam on the active medium. ![]() The superiority of the proposed architecture is demonstrated by analyzing the variations of the size and divergence of the output beam in form of a Taylor expansion around the design value for variations of the thermal lens in the active medium. We found that the proposed multi-pass amplifier is robust to variations of the active medium dioptric power. We present a novel architecture for a multi-pass amplifier based on a succession of optical Fourier transforms and short propagations that shows a superior stability for variations of the thermal lens compared to state-of-the-art 4f-based amplifiers. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |