Ring Fiber with Asymmetric Grating and Its Application in Orbital Angular Momentum Generation

An orbital angular momentum, asymmetric technology, applied in the field of optics, can solve the problems of poor long-term stability, large structure size, narrow orbital angular momentum wavelength, etc., to achieve effective separation and stable transmission
CN107462948BActive Publication Date: 2019-10-25NORTHEASTERN UNIV LIAONING
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
NORTHEASTERN UNIV LIAONING
Publication Date
2019-10-25

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Abstract

The present invention proposes a ring-shaped optical fiber with an asymmetric grating and its application in orbital angular momentum generation. Hollow-core ring fiber can increase the effective refractive index difference between quasi-degenerate modes, thereby avoiding crosstalk between modes. The long-period grating inscribed on the half-ring of the hollow-core ring fiber breaks the circular symmetry structure of the fiber and realizes conversion between angular modes of non-same order. When the input light is a circularly polarized fundamental mode, a first-order orbital angular momentum mode can be generated. The hollow core of the hollow-core ring fiber is filled with optical functional materials with adjustable refractive index. The wavelength that generates the orbital angular momentum mode can be tuned by the refractive index of the liquid. Therefore, this structure can generate the orbital angular momentum mode within an adjustable broadband wavelength range. The simulation shows that when the grating period is 292μm and the grating length is 1.460cm, the angular momentum mode conversion rate is higher than 90% in the broadband wavelength range up to 237nm, and the maximum conversion rate is 98.91%. The refractive index of the filled liquid has an impact on the orbital angular momentum mode. The wavelength modulation rate is 7400nm / RIU.
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Description

technical field

[0001] The invention belongs to the field of optical technology, and relates to a ring-shaped optical fiber with an asymmetric long-period grating and its application in the generation of orbital angular momentum. Background technique

[0002] Optical orbital angular momentum corresponds to the rotation of the optical phase structure, revealing another degree of freedom of light that is completely different from spin, and thus has attracted much attention. At present, applications based on optical orbital angular momentum have made remarkable progress in the fields of microscopic imaging, target detection, optical communication, radio frequency communication, etc., but there are still many problems to be solved. The generation of optical orbital angular momentum is One of the most fundamental problems.

[0003] Devices that generate orbital angular momentum modes in free space include spatial beam modulators, helical phase plates, cylindrical lenses, etc. A...

Claims

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