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Sub-wavelength focusing lens integrated on optical fiber end face

A technology of focusing lens and fiber end face, which is applied to the coupling of optical waveguides, etc., can solve the problems of not being able to fully enter the sub-wavelength region, application limitations, etc., and achieve the effects of simple structure, high feasibility and high light transmission efficiency.

Inactive Publication Date: 2012-05-16
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] 1. Only in the range of about 2λ close to the exit surface of the lens has good focus, which greatly limits its application
[0010] 2. The concentrated beam is affected by the conical surface defect of the axicon lens and deviates from the ideal sub-wavelength focusing ability, usually only close to the sub-wavelength without being able to fully enter the sub-wavelength region

Method used

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  • Sub-wavelength focusing lens integrated on optical fiber end face
  • Sub-wavelength focusing lens integrated on optical fiber end face
  • Sub-wavelength focusing lens integrated on optical fiber end face

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] A schematic diagram of the structure of a tapered lens for sub-wavelength focusing on an optical fiber is as follows: figure 1 As shown, the specific design process is as follows:

[0039] (1) Determine the fiber structure at the front end of the lens, core radius 8.3um / refractive index 1.4675, cladding radius 125um / refractive index 1.4622.

[0040] (2) Select the incident wavelength as 1550nm and the lens refractive index as 1.45.

[0041] (3) Make sure that the exit aperture of the lens is D=18um, and the height of the lens is 70um.

[0042] (4) Make sure that the outer cone angle of the lens is 40 degrees, and the inner cone angle is 19 degrees.

[0043] (5) Using the parameters determined in steps (1) (2) (3), 3D-BPM is used for simulation calculation.

[0044] The simulation results are as figure 2 As shown, in the range of 0~15um behind the exit end of the lens, the FWHM of the focused beam section changes from 0.531um to 0.870um. It is also measured that the intensity of t...

Embodiment 2

[0047] The difference between this embodiment and Embodiment 1 is that the exit aperture D of the lens is increased to 30um, the outer cone angle is reduced to 20 degrees, and the inner cone angle is increased to 28.5 degrees. At this time, within the range of 0~15um behind the exit end of the lens, the FWHM on the focused beam section changes from 0.662um to 0.849um. It is also measured that the intensity of the focused spot in this area is greater than the incident light intensity, and the highest intensity of the focused spot is about The incident light intensity is 5 times, that is, the lens of this parameter can also achieve sub-wavelength focusing on the optical fiber.

Embodiment 3

[0049] The difference between this embodiment and the first embodiment is that the lens height is increased to 300um, and the outer cone angle is increased to 46 degrees. At this time, within the range of 11~18um behind the exit end of the lens, the FWHM of the focused beam section changes from 0.737um to 0.982um. It is also measured that the intensity of the focused spot in this area is greater than the incident light, and the highest light intensity is about the incident light. 5.3 times stronger, that is, the lens of this parameter can also achieve sub-wavelength focusing on the fiber.

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Abstract

The invention discloses a sub-wavelength focusing lens integrated on an optical fiber end face. A lens basic structure is an upright round platform in butt join with an optical fiber and the upper end face of the round platform is a hollow reversed cone, wherein an incidence wavelength is in a range from 400nm to 1,600 nm; the refractive index of a lens is close to the refractive index of a coupled optical fiber; under the condition that the refractive index of the lens ranges from 1.4 to 1.7, the changing range of an emergent opening diameter D of the lens is 8-40 microns and the changing range of the height H is 50-400 microns; the changing range of an external tapered angle (Angle 1) of the lens is 20-60 DEG and the changing range of an internal tapered angle (Angle 2) of the lens is 10-40 DEG. The sub-wavelength focusing lens integrated on the optical fiber end face has the advantages of small focused light spots, high light throughput efficiency and capability of being integrated with the optical fiber and the batch production can be realized by adopting a high-polymer macro-nano contact molding method.

Description

Technical field [0001] The invention relates to a sub-wavelength focusing lens, in particular to a lens for realizing sub-wavelength focusing with high transmittance on an optical fiber head. Background technique [0002] Sub-wavelength focusing has always been one of the most concerned directions by optical researchers and related industrial engineers, and it has also been a hot research topic in recent decades. With the development of science and technology, higher and higher requirements are put forward for optical spatial resolution. [0003] The focal beam with a spot size smaller than the wavelength is used in three-dimensional optical data storage, lithography technology, material processing, nanoparticle movement operation and control, biomedical imaging, Raman spectroscopy, second harmonic excitation, near-field scanning and laser confocal microscopy China is crucial. For example, in optical data storage, a small spot can increase storage density and storage capacity; in...

Claims

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Application Information

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IPC IPC(8): G02B6/32
Inventor 吴兴坤黄河
Owner ZHEJIANG UNIV