SPIE Photonics West 2016 Tomohiro Tetsumoto

[9759-7] Ultrafast third-harmonic spectroscopy of single nanoantennas fabricated using helium-ion beam lithography

I attended the session on FIB fabrication technology. The background of the research was the need to localize optical modes in a very small volume in order to realize ultrafast optical transistors, and the presentation was about the fabrication of bow-tie type nano antennas and their performance. In this presentation, FIB with He+ ions was introduced. In the presentation, an antenna with an amazing nano gap of 6 nm in gap length was introduced (Fig. 2(a)). The antenna fabricated with He+ ions showed higher nonlinearity (Fig. 2(b)) and better polarization dependence than the antenna fabricated with Ga+ ions (gap = 20 nm). Microscopy GmbH, and Univ. Bielefeld. The relationship is beneficial to both the university and the company, as the developed advanced technology is effectively used for basic research at the university, and the findings are immediately fed back to the company side.

FIB is a simple method in that it does not require lithography and can directly create patterns, enabling highly accurate microfabrication. On the other hand, FIB is not good at large-area pattern fabrication, and has the problems of non-smooth stitching at the pattern joints and long drawing time. Although we usually see beautifully finished structures, it is necessary to take into account the effects of ion scattering and to remove the effects of substrate electrification. In general, I got the impression that this technology is still more for research and development than for industrial use, as it is suitable for metal processing of fine patterns such as plasmon research.

[9759-14] Packaging and micro-structuring for enabling multi-functional fiber-cladding photonics and lab-in-fiber

A presentation from the University of Toronto, Canada. The presentation is about the fabrication of waveguides, liquid channels, and other optical elements in optical fibers by femtosecond laser imaging. Although processing using femtolasers to modify glass is a familiar topic, this is the first time I have heard of a presentation on the integration of various elements as in this case. In the presentation, interesting applications such as shape sensing of fibers (Opt. Express, 21(20), 24076-24086 (2013)) were introduced. I was impressed by the fact that the technology can be used in a variety of ways if it is mastered. In fact, they seem to be actively collaborating with companies, and Oz Optics (a VOA company) is one of the joint authors of the following article.

[9742-34] Integrated nanophotonic devices for optical interconnections

Fig. 4(a) shows the structure of the device, which consists of a waveguide and a side-coupled ring resonator, and eight side-coupled waveguides with the same coupling coefficient. There is a ring resonator side-coupled to a waveguide, and inside the ring resonator are eight side-coupled waveguides with the same coupling coefficient. The light entering the eight waveguides from the ring resonator is coupled at different positions and has different phase relationships, so the light emitted into space becomes their super modes and has angular orbital momentum. Since light with angular orbital momentum (optical orbital angular momentum: OAM) has numerous eigenstates, it can be used to increase the information capacity of data communications. In the presentation, it was shown that the shape of the OAM beam emitted from each mode of the ring resonator is different (Fig. 4(b)) and that the shape of the OAM beam was experimentally controlled by using a phase shifter (Scientific Reports 5, 10958 (2015).) The paper uses IMEs for fabrication (the paper does not seem to mention the use of IMEs for this element, so it may be for other devices).