Open AccessAdaptive conversion of multimode beam to near-diffraction-limited flattop beam based on dual-phase-only liquid-crystal spatial light modulators
Author(s) -
Haotong Ma,
Haichuan Zhao,
Pu Zhang,
Xiaolin Wang,
Yanxing Ma,
Xiaojun Xu,
Zejin Liu
Publication year - 2010
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.18.027723
Subject(s) - optics , laser beam quality , multi mode optical fiber , m squared , beam (structure) , wavefront , materials science , phase (matter) , beam diameter , diffraction , spatial light modulator , collimated light , physics , optical fiber , laser , quantum mechanics , laser beams
We propose and demonstrate the adaptive conversion of a multimode beam into a near-diffraction-limited flattop beam in the near field based on a combination of dual-phase-only liquid-crystal spatial light modulators (LC-SLMs) and the stochastic parallel gradient descent (SPGD) algorithm. One phase-only LC-SLM redistributes the intensity of the multimode beam, and the other compensates the wavefront of the output beam. The SPGD algorithm adaptively optimizes the phase distributions of dual-phase-only LC-SLMs to reduce the variance between the actual beam shape and the target beam shape. The experimental results on a fiber multimode beam show that the system is capable of adaptively creating square and rectangle flattop beams with desired parameters. Beam quality can be greatly improved by this system. The power in the main lobe of the far-field spot is about 4 times larger than that of the input multimode beam.