Article

# Generation of an optical vortex with a segmented deformable mirror.

Department of Physics and Optical Science, University of North Carolina at Charlotte, Charlotte, NC 28223, USA.

Applied Optics (Impact Factor: 1.69). 12/2008; 47(33):6300-6. DOI: 10.1364/AO.47.006300 Source: PubMed

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**ABSTRACT:**We propose a method of converting the topological charge (TC) of an incident vortex light wave with spiral-slit screens. The phase in the incident vortex beam is redistributed via the optical path adjustment realized by changing the in-plane radial distance of the spiral slit. We numerically calculate the light field with Fresnel diffraction theory, and find the expected TC conversion on the observation plane. Our calculations also show that screens of pinholes distributed in a spiral curve can be used for the implementation instead of spiral slits. The method can also be used to distinguish the TCs of the incident vortices by reading the diffracted intensity patterns.Chinese Physics Letters 10/2013; 30(10):4206-. · 0.92 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We propose a convenient approach for managing orbital angular momentum (OAM) of second-harmonic photons generated by a quadratic nonlinear interaction under noncolinear type-I phase matching condition. Since the OAMs of two fundamental photons can be flexibly controlled by using computer-generated holograms, we were able to realize arbitrary combination of both OAMs and experimentally confirm the OAM conservation selection rule ℓ2ω=ℓω'+ℓω'' in general cases. In particular, our approach could be used to generate the second-harmonic photon states with fractional and odd-order OAMs.Physical Review A 09/2013; · 3.04 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We propose a novel and simple method for generating optical vortex with high topological charge (TC), merely using an asymmetrical pinhole plate illuminated by plane wave. N pinholes are arranged along a particular spiral line around the plate origin, with constant azimuth angle increment and varied radial distances. The radial differences introduce a constant variation of m/N wavelength to the optical paths from the N pinholes to the observation plane origin, and this increases the phases of the transmitting waves by progressively 2mπ/Nand totally2mπ. We numerically calculate the transmitted light field according to the Fresnel diffraction theory, and find the vortex with TC m around the observation plane origin. The experimental verifications are performed using some self-made asymmetrical pinhole plates fabricated by a femtosecond laser, with the high TC vortices both generated and detected in a Mach-Zehnder type interferometer. The experimental results coincide with the theoretical simulations well.Optics Express 07/2013; 21(13):15755-15764. · 3.55 Impact Factor

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