1178 J, 527 nm near diffraction limited laser based on a complete closed-loop adaptive optics controlled off-axis multi-pass amplification laser system

Abstract

A 1178 J near diffraction limited 527 nm laser is realized in a complete closed-loop adaptive optics (AO) controlled off-axis multi-pass amplification laser system. Generated from a fiber laser and amplified by the pre-amplifier and the main amplifier, a 1053 nm laser beam with the energy of 1900 J is obtained and converted into a 527 nm laser beam by a KDP crystal with 62% conversion efficiency, 1178 J and beam quality of 7.93 times the diffraction limit (DL). By using a complete closed-loop AO configuration, the static and dynamic wavefront distortions of the laser system are measured and compensated. After correction, the diameter of the circle enclosing 80% energy is improved remarkably from 7.93DL to 1.29DL. The focal spot is highly concentrated and the 1178 J, 527 nm near diffraction limited laser is achieved.

Wavefront Correction in Vacuum of SULF-1PW Laser Beamline

“…Wavefront aberrations are the main limitation to the realization of ideal focal spots and it can be divided into two categories: static aberration, resulting from the aberration of optical elements; and dynamic aberration, mostly originating from the thermal loading in the laser system [11]. The adaptive optical system (AOS) based on a deformable mirror (DM) is generally applied in high peak power lasers, in order to correct the wavefront aberration and therefore improve the focusing quality [12][13][14][15][16]. Sometimes, double AOSs with cascaded correction functions are also used, in view of the large beam size and serious aberration [17][18][19][20].…”

The Multiparameter Measurement Technique in a Large-Aperture Rectangular Laser Beam Aberration Correction System

“…In 2018, Yang et al determined the beam quality factor for a 750-MW solid-state slab laser to be 1.64 times the diffraction limit using an AO system combined with the related low-order aberration-correction approach [10]. In 2021, Wang et al employed a completely closed-loop AO-controlled off-axis multirange amplification system to strengthen the beam quality of an 1178-J, 527-nm laser to almost the diffraction limit [11].…”

“…Essential research has been conducted to address the abovementioned issues. To meet the requirement for large-aperture wave-front detection, Wang et al [11] established a Keplerian system using two lenses to compress a 260 mm × 260 mm square aperture laser beam. Nonetheless, the total focal lengths of this Keplerian system reached 2.05 m. Despite the employment of a reflector to fold the optical path, the detection 2 > Manuscript number: PJ-013517-2022 < unit was still huge and could only measure a single parameter.…”