Abstract

Shaping of the spatial intensity profiles by apodized apertures (AAs) is necessary for many practical problems in laser physics and their applications¹,²: avoiding hard-edge Fresnel diffraction effects in the beam cross-section by rounding the uniform spatial intensity profile at the edges; generation diffraction-limited beams without side lobes, diminishing beam divergence and even sometimes increasing output energy in single-mode lasing by using AAs inside the resonator; increasing the second-harmonic conversion efficiency; compensation of the large scale in homogeneities in beam cross-section, e.g., elimination of pumping inhomogeneity in active elements; formation of a time-profiled pulse by electrooptical deflectors; experiments of interaction of laser radiation with matter, which require Gaussian or super-Gaussian spatial intensity profiles; optical processors, etc. In this paper four types of AA for lasers are presented, namely: induced absorption, photodestruction (including photooxidation) and thermochemical reduction AA work in UV, visible, near and partially mid-IR regions. The working principle of frustrated total internal reflection AAs is valid for the large spectral region including UV, visible, IR, submillimeter and millimeter spectral bands. AA fabrication techniques are considered and the results of investigations both outside resonator AA and inside AA in beams of 0.342-, 0.63-, 1.315-, 2.79-, 2.94-, 5.6-, and 10.6-μm lasers are discussed in comparison with other types of AA.

© 1991 Optical Society of America