Bowtie nano-aperture as interface between near-fields and a single-mode fiber

Abstract

We present the development and study of a single bowtie nano-aperture (BNA) at the end of a monomode optical fiber as an interface between near-fields/nano-optical objects and the fiber mode. To optimize energy conversion between BNA and the single fiber mode, the BNA is opened at the apex of a specially designed polymer fiber tip which acts as an efficient mediator (like a horn optical antenna) between the two systems. As a first application, we propose to use our device as polarizing electric-field nanocollector for scanning near-field optical microscopy (SNOM). However, this BNA-on-fiber probe may also find applications in nanolithography, addressing and telecommunications as well as in situ biological and chemical probing and trapping.

The Optical Fiber Tip: An Inherently Light‐Coupled Microscopic Platform for Micro‐ and Nanotechnologies

“…In addition to circular apertures, C‐shaped nano‐apertures have demonstrated increased transmission by exciting both propagating modes and surface plasmon excitation in the aperture . Bowtie nano‐apertures, as in Figure , have demonstrated polarization sensitivity in receiving mode, and enhancement of emitted light intensity by several hundred times …”

“…These polymer tips can be converted to SNOM tips by (d) coating with metal and FIB milling a nano‐aperture. Reproduced with permission …”

“…In the most general sense, the scope of application of fiber tip devices includes: Remote optical sensing , where propagating light interrogates a sensing element at the fiber tip and returns along the same fiber for collection and analysis, providing immunity to electromagnetic interference and access to remote and hostile environments; Biomedicine , where the small cross‐section of the fiber allows minimally intrusive in situ and in vivo interrogation of organisms, even allowing the manipulation of individual cells; Beam shaping , where lenses and diffracting elements modify optical power distribution, filter wavelengths, and enable versatile and efficient interfacing with integrated optical devices; Opto‐Mechanical Systems , where tip‐mounted diaphragms and cantilevers allow pressure sensors to be deployed in unique environments, and create novel probes for near‐field and atomic‐force microscopy; Nanophotonics , where nano‐structures make efficient use of the limited real‐estate on the fiber tip, and allow the exploration of opportunities in plasmonics and sensing by SERS …”

“…The fabrication techniques that have been applied to fiber tips include: Planar fabrication technologies , which have been applied intrinsically and extrinsically to the fiber tip, and include photolithography, nanoimprinting, interference lithography, electron‐beam lithography, focused ion‐beam milling, two‐photon polymerization, femtosecond laser ablation, and thin‐film deposition; Hybrid techniques , which transfer micro and nano structures to the fiber tip, thereby retaining the benefits of fabricating on large planar substrates; and Through‐fiber patterning , where the optical power distribution within the fiber can create unique geometries of photosensitive material at the fiber tip . Finally, this article reviews the techniques, challenges and prospects for mass production of patterned fiber tips, where the microscopic cross‐section and inherently serial nature of the optical fiber stand in stark contrast to the large size and parallel die processing of traditional planar substrates.…”

Stand-Alone Three-Dimensional Optical Tweezers Based on Fibred Bowtie Nanoaperture

“…The originality of our work deals with the use of a fibred nanotweezers based on a Bowtie Nanoaperture Antenna (BNA) that is engraved at the tip apex of a metal coated near-field optical microscope probe. This BNA tip (BNAT) provides standalone optical nanosource directly excited with in-fiber illumination [25]. Emitted signal by the fiber tip only results from the BNA resonance, this means that there is no direct coupling between the fiber guided mode and the free propagating field issued from the tip [26].…”