Zhao Q, Qu J, Peng G, Yu C. Endless Single-Mode Photonics Crystal Fiber Metalens for Broadband and Efficient Focusing in Near-Infrared Range.
MICROMACHINES 2021;
12:mi12020219. [PMID:
33670081 PMCID:
PMC7926773 DOI:
10.3390/mi12020219]
[Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 02/17/2021] [Accepted: 02/18/2021] [Indexed: 11/23/2022]
Abstract
The advent of the ‘lab-on-fiber’ concept has boosted the prosperity of optical fiber-based platforms integrated with nanostructured metasurface technology which are capable of controlling the light at the nanoscale for multifunctional applications. Here, we propose an endless single-mode large-mode-area photonic crystal fiber (LMA-PCF) integrated metalens for broadband and efficient focusing from 800 to 1550 nm. In the present work, the optical properties of the substrate LMA-PCF were investigated, and the metalens, consisting of dielectric TiO2 nanorods with varying radii, was elaborately designed in the fiber core region with a diameter of 48 μm to cover the required phase profile for efficient focusing with a high transmission. The focusing characteristics of the designed metalens were also investigated in detail over a wide wavelength range. It is shown that the in-fiber metalens is capable of converging the incident beams into the bright, symmetric, and legible focal spots with a large focal length of 315–380 μm depending on the operating wavelength. A high and average focusing efficiency of 70% was also obtained with varying wavelengths. It is believed the proposed fiber metalens may show great potential in applications including fiber laser configuration, machining, and fiber communication.
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