title: Coherent beam transformations using multimode waveguides.
abstract: Physical insights and characteristics of beam transformations based on multimode interference (MMI) in multimode waveguides are illuminated and analyzed. Our calculations show that, utilizing a short piece of cylindrical multimode waveguide, an input Gaussian beam can be readily transformed to frequently desired beams including top-hat, donut-shaped, taper-shaped, and Bessel-like beams in the Fresnel or the Fraunhofer diffraction range, or even in both ranges. This is a consequence of diffractive propagation of the field exiting the waveguide. The performance of the beam shaper based on MMI can be controlled via tailoring the dimensions of the multimode waveguide or changing the signal wavelength. This beam shaping technique is investigated experimentally using monolithic fiber devices consisting of a short piece of multimode fiber (approximately 10 mm long) and a single-mode signal delivery fiber.
authors.affiliation: College of Optical Sciences, University of Arizona, 1641 East University Boulevard, Tucson, Arizona 85721, USA. xszhu@email.arizona.edu
authors.forename: X
authors.initials: X
authors.lastname: Zhu
authors.forename: A
authors.initials: A
authors.lastname: Schülzgen
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: H
authors.initials: H
authors.lastname: Wei
authors.forename: J V
authors.initials: JV
authors.lastname: Moloney
authors.forename: N
authors.initials: N
authors.lastname: Peyghambarian
mesh_terms: D000669:Amplifiers, Electronic; D004867:Equipment Design; D005336:Fiber Optic Technology; D007834:Lasers; D015233:Models, Statistical; D016011:Normal Distribution; D055096:Optical Devices; D055100:Optical Fibers; D055095:Optics and Photonics; D012031:Refractometry / Q000295:instrumentation