Ultra-Broadband Confinement in Deep Sub-Wavelength Air Hole of a Suspended Core Fiber

Author

Hasan, Dihan ; Alam, Md Shamsul

Author_Institution

Dept. of Electr. & Comput. Eng., Nat. Univ. of Singapore, Singapore, Singapore

Volume

32

Issue

8

fYear

2014

fDate

15-Apr-14

Firstpage

1434

Lastpage

1441

Abstract

We demonstrate low loss (0.4043 dB/Km at 1.55 μm) deep sub-wavelength broadband evanescent field confinement in low index material from near IR to mid IR wavelengths with the aid of an specialty optical fiber whilst achieving at least 1.5 dB improvement of figure of merit over the previous design. Plane strain analysis has been conducted to foresee fiber material dependent fabrication challenges associated with such nanoscale feature due to thermal stress. Size dependence of air hole is explained rigorously by modifying the existent slot waveguide model. We report significant improvement of field intensity, interaction length, bandwidth and surface sensitivity over the conventional free standing nanowire structure. The effect of metal layer thickness on surface plasmon resonance sensitivity is explored as well. A method to obtain strong evanescent field in such structure for medical sensing is also demonstrated. The proposed technique to enhance sub-wavelength confinement is expected to be of potential engineering merits for optical nanosensors, atomic scale waveguide for single molecule inspection and ultra-low mode volume cavity.

Keywords

fibre optic sensors; nanomedicine; nanophotonics; nanosensors; nanowires; optical fibre fabrication; optical fibre losses; optical materials; surface plasmon resonance; thermal stresses; atomic scale waveguide; bandwidth; conventional free standing nanowire structure; deep subwavelength air hole; fiber material dependent fabrication; field intensity; figure of merit; gain 1.5 dB; interaction length; low index material; low loss deep subwavelength broadband evanescent field confinement; medical sensing; metal layer thickness; mid IR wavelengths; nanoscale feature; optical nanosensors; plane strain analysis; single molecule inspection; size dependence; slot waveguide model; specialty optical fiber; strong evanescent field; subwavelength confinement; surface plasmon resonance sensitivity; surface sensitivity; suspended core fiber; thermal stress; ultrabroadband confinement; ultralow mode volume cavity; wavelength 1.55 mum; Indexes; Materials; Optical fiber devices; Optical fiber dispersion; Optical fibers; Optical surface waves; Characteristic decay length; evanescent sensing; field intensity; slot waveguide; sub-wavelength confinement; suspended core fiber;

fLanguage

English

Journal_Title

Lightwave Technology, Journal of

Publisher

ieee

ISSN

0733-8724

Type

jour

DOI

10.1109/JLT.2014.2306292

Filename

6742596