Laguerre Gaussian optical parametric oscillator with tunable broadband topological charges

Abstract

The invention discloses a Laguerre Gaussian optical parametric oscillator with tunable broadband topological charges. The oscillator comprises a nanosecond pulse laser, a beam shaping device, a coating cavity mirror, a periodically poled lithium niobate crystal, a temperature control device, a polarization element and a vector vortex wave plate, wherein the coating cavity mirror comprises a coating front cavity mirror and a coating rear cavity mirror which form a resonant cavity. The oscillator is advantaged in that relative positions of a vector vortex wave plate and the coating front cavitymirror meet the condition that a ratio of a concave mirror to a concave mirror is 1: 1, a self-reproduction cavity mode with smooth transition from a solid light beam to the hollow Laguerre Gaussian light beam is formed according to the imaging relation of the solid light beam and the hollow Laguerre Gaussian light beam, coupling efficiency of the cavity mode and the pump light is improved, intra-cavity loss is reduced, and finally high-efficiency, high-purity and wavelength and topological charge tunable Laguerre Gaussian light beam output is achieved.

Description

technical field [0001] The invention relates to an optical parametric oscillator, in particular to an optical parametric oscillator outputting Laguerre-Gauss beams with broadband and tunable topological charges. Background technique [0002] The Laguerre-Gaussian (LG) modes are a set of eigensolutions of the paraxial approximate wave equation in the cylindrical coordinate system. Different Laguerre-Gaussian modes are marked by the angular index l and the radial index p, denoted by express. When l,p=0, the Laguerre-Gaussian beam degenerates into a fundamental-mode Gaussian beam; when l≠0, each photon in the Laguerre-Gauerian beam carries an orbital angular momentum of The angular exponent l is also called the topological charge. Laguerre-Gaussian beams carrying orbital angular momentum have a wide range of applications in optical manipulation, optical precision measurement, optical communication, super-resolution imaging, and quantum information processing. The high-puri...

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Problems solved by technology

Laguerre-Gaussian beams produced by such methods typically have low mode purity and the systems are not sufficiently integrated

The second type of method can directly output the Laguerre-Gaussian beam from the resonator, and use the mode selection function of the resonator to improve the mode purity of the output beam, such as using a beam with orbital angular momentum as the pump light [Controlled switching of orbital angular momentum in an optical parametric oscillator], due to the conservation of orbital angular momentum in the process of parametric down-conversion, the generated parametric light carries orbital angular momentum, and the interaction with the resonant cavity can directly output Laguerre-Gaussian mode, but the annular pump beam light carrying orbital angular momentum The power density is low, resulting in low frequency conversion efficiency; in addition, Gaussian beam pumping is also used, and the output of Laguerre Gaussian beams is realized by adding a mode conversion device in the resonator, for example [a tunable Laguerre with an output of 1064nm Lasers with Gaussian beams], but this solution only achieves single-wavelength Laguerre Gaussian beam output, and uses pinhole mode selection to improve the purity of the output mode while increasing the loss in the resonator cavity, which needs to be improved in terms of efficiency improvement

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