Nanocraters Improve Optical Nanofibers

Scanning electron microscopy image of the resulting uniformity and dimensions of photonic crystals induced on nanofibers using femtosecond laser-induced ablation. (Source: UEC)

Control­ling and mani­pulating the interaction of light with nano­structures offers the promise of new and inno­vative techno­logical appli­cations ranging from nano­lasers and sensors to quantum computing. However, in spite of tremendous advances in nano­technology that has enabled the fabri­cation of one and two dimen­sional structures such as photonic crystal cavities, effi­ciently inte­grating nano­crystal cavities with modern optical fibers in communi­cations networks is proving to be difficult.

Now, Kohzo Hakuta and col­leagues at the Univer­sity of Electro-Communi­cations in Tokyo report on the reali­zation of one dimen­sional arrays of nano­meter sized holes or nano­craters on the surfaces of optical nano­fibers by simply irra­diating them with a single pulse of ultra­short light from a femto­second laser. These nano­fiber based photonic crystal cavities are expected to find new appli­cations in nano­photonics and quantum infor­mation science.

Speci­fically, the researchers used a laser with a 400 nm wavelength and 120 fs pulse width to ablate thousands of 50 – 250 nm-diameter nano­craters with a perio­dicity of 350 nm over a 1 mm length in 450 – 550 nm-diameter nano­fibers. Notably, in this procedure the nano­fiber acts as a lens and focuses the incident laser light onto its shadow side, and the use of only one pulse elimi­nates structural imper­fections due to mechanical vibra­tions.

The resulting one dimen­sional photonic cavities exhibited strong broadband reflec­tance and high optical trans­mission. The researchers state: “The strong confine­ment of the field, both transverse and longi­tudinal, in the nano­fiber-based PhC cavities and the efficient inte­gration to the fiber networks, may open new possi­bilities for nano­photonic appli­cations and quantum infor­mation science.” (Source: UEC)

Reference: K. P. Nayak et al.: Fabrication of 1-D Photonic Crystal Cavity on a Nanofiber Using Femtosecond Laser-induced Ablation, J. Vis. Exp. 120, e55136 (2017); DOI: 10.3791/55136

Link: Center for Photonic Innovations, University of Electro-Communications, Tokyo, Japan

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