PECS XII Tomohiro Tetsumoto

　From July 17 to 21, I attended PECS XII held at the University of York in England (Fig. 1). As the name "Photonic and Electromagnetic Crystal Structures" suggests, this conference is held every two years in a different location. The next conference will be hosted by M. Loncar and will be held near Harvard University in Boston. It was a very high-level conference with top-notch researchers from all over the world (almost everyone I could think of who is a photonic crystal researcher was there). https://www.york.ac.uk/physics/pecs-xii/technicalprogram/fullprogram/ The number of participants was very high. (There were also some great names such as E. Yablonovitch, J. Pendry, and F. Cappasso (via skype)). The only disappointment was the cancellation of Painter's presentation. Instead, the sponsor, Nat. Photonics, gave a talk titled "Ten years of Nat. Photonics," in which the opening slide showed Dr. Tanabe's presentation of the world's first 10⁶The paper on photonic crystal resonators that exceeded the

One of the unique features of this year's conference was the discussion session. The topics of discussion were as follows: "Why does the π/2 shift occur when light enters the resonator? Why does the π/2 shift occur when light is input to the resonator? The moderator, T. Krauss, was in charge well, and the discussions were lively, though sometimes digressing. What I felt there was that people from all over the world had the same awareness of the issues. Some of the topics mentioned above have been raised in Tanabe Lab. It was interesting to hear other people's opinions about such common problems. I thought it was a good trial.

I was also impressed by the strong research capabilities of Japanese research groups in the field of photonic crystals. In contrast to the WGM resonator field, where there are almost no Japanese researchers, in the photonic crystal field, there are many leading research groups including Noda Lab, which is pioneering various applications in the photonic crystal field based on ultra-high Q resonator fabrication technology, Baba Lab for slow light and ultra-high sensitivity biosensing, NTT's Notomi Lab for optical signal processing, and the Arakawa-Iwamoto Lab for quantum optics. The Noda Lab. is pioneering various applications in the field of crystallography, Baba Lab. On the other hand, other groups seem to have followed the Japanese group and steered their research toward other fields such as plasmons and metamaterials, rather than competing with them. This is a wise decision in the field of photonic crystals, where applications have been slow to emerge. The cost of photonic crystals is so low that it is difficult to know whether they can be used or not, even though high technology is required to fabricate them. I have the impression that many new applications of photonic crystals have emerged in recent years, but otherwise, the Japanese group may have been left behind in terms of applications. I felt the importance of continuous participation in academic conferences and consideration of research directions to avoid isolation in research fields and lagging behind when new fields emerge. Tanabe Lab. at Keio University is hardly known in the industry, so we felt the need to disseminate our research with impact.