IEEE Photonics Conference Tomohiro Tetsumoto

2014-01-19 2022-09-24 miyahara

Research

Report on Participation in IEEE PHOTONICS CONFERENCE 2014

Tomohiro Tetsumoto, 2nd year master student, Tanabe Laboratory

October 12-16 in San Diego, California, U.S.A.
We have attended IEEE Photonics Conference 2014 and report an overview of our activities.

[Society Overview].

IEEE Photonics Conference is a research conference on silicon photonics related devices and systems organized by IEEE, USA. This year, there were many reports on microcavity-related research, and I was able to listen to talks by well-known researchers whose names I know, including Vahala. Many of the presentations were by invited speakers. According to what I heard, CLEO is a place to listen to various presentations and collect information, while OSA and this IPC are places to listen to and study a variety of presentations. The conference was not so big, the venue was a part of one floor of a hotel, there were about 200~300 participants (estimated by Terumoto), and I had an impression that researchers in quite close fields were gathered there. Therefore, I could meet people often. I think it is a good conference to make acquaintances. I myself got acquainted with a student of Weiner Laboratory at Purdue University who asked me a question after my presentation (he was always looking for someone, saying "I'm looking for someone..."). He was friends with a student from Purdue University whom I had met at a previous conference). ) I'm always looking for someone. It's fun to have more acquaintances, so I think it's a good idea to be proactive about making friends.

[regarding his own presentation].

I revised my presentation materials and manuscript until the last minute and practiced until the very last minute. I had almost memorized the manuscript itself, but after arriving at the site, I realized that the content of the presentation would not fit within the presentation time. On the day of the presentation, I managed to keep the presentation within the time limit and gave it a score of about 70 points. I think I was able to give a presentation with a passing grade that I can do now. After the presentation, I received three questions (speed of operation, reason for using a resonator for optical path conversion, and what power is used). Basically, the questions were about the design of my research. The third question, "What kind of force do you use?" made me think that in the field of opto-mechanics, it is easy to convey what kind of force is used by talking about "optical radiation force". Certainly, the optical radiation pressure that I am using in the design of this research is an attractive force, and it is difficult to equate it with radiation pressure, which is generated when light strikes an object. I myself believe that there is a potential similar to that of gravity, and understand that the structure of the resonator acts as a force that pulls the internal light into a lower energy state (shorter resonance wavelength). However, I am not sure if this understanding is accurate, and the use of terms such as radiation pressure and optical force is not always appropriate.

Research Topics

As mentioned above, there were many reports related to microcavities at the conference, so there were many topics that I was familiar with. SNAP by Kobatake and fluid sensing by opto-mechanics by Kobayashi, both of which I supported in Spring Coro, were presented. There were also several researchers who used IMEC for metamaterials and spot-size converters, which are difficult to fabricate, and I felt that the hurdle for fabrication is getting lower thanks to the spread of foundries and improved accuracy.
Below are some of the presentations that were of particular interest to me at the conference.

[TuF3.1: X. Jiang, et al., Ultrahigh-Q microcavities with highly directional emission].Presentation by Prof. Xiao's group at Peking University. I had heard that toroids can be made elliptical to allow directional spatial input/output, but this time I listened to a thorough explanation of the principle again. It seems that chaos is involved at a deep level, but in the end, it seems that the toroidal structure is made in such a way that only a part of the total reflection condition is not satisfied. However, I was surprised at the high precision of the fabrication. I wonder if it is possible to control the resonance wavelength of the toroid with high precision by using it as a reference. I think this technology is necessary for packaging. One of the advantages of spatial coupling is that the coupling Q-value is stable, and they are trying to use this to achieve ultra-high precision sensing from mode broadening rather than mode splitting of the resonance spectrum. After hearing it again, I thought it sounded reasonable.

[WH.4.3: B. Oner, et al., Broadband one way propagation via dielectric waveguides with unequal effective index].
This is a story about the numerical analysis of an MZI type interferometer structure isolator. The principle is simple and is presented here. The device configuration is, for example, as follows. A single waveguide extends from the left and is designed to propagate only the fundamental mode. The two waveguides have different widths. The separated waveguides connect on the right side to a waveguide that can propagate both first- and second-order modes.
The two separate waveguides have different propagation constants due to their different widths, and are set to lengths that invert the phase by exactly π. Therefore, light input to the two waveguides simultaneously forms a mode with second-order odd symmetry when the two waveguides meet again. In this case, light input from the right cannot be guided through the tapered structure to the left waveguide because it cannot shift to the first-order mode on its way to the left waveguide, while light input from the left can propagate through the right waveguide as a mode with second-order odd symmetry. In this way, it works like an isolator. The two split waveguides are almost the same width, which allows for a wider operating bandwidth.

[WH.4. 4: R. Van Laer, et al., Observation of 4.4 dB brillouin gain in a silicon photonic wire].
The contents of this paper show that high gain Brillouin scattering was excited inductively using a silicon wire. To reduce mechanical vibration loss, the silica layer under the silicon layer was cut to about 10 nm, and by increasing the photon-phonon interaction distance (about several centimeters), a gain-loss ratio of nine times higher than that of conventional devices could be obtained. The concept is exactly the same as the design of photonic-phononic resonators. In a waveguide type resonator, it seems that there are equal amounts of traveling wave and backward wave in the optical resonator, but can both Raman light be emitted? I had a prejudice that the excitation of Brillouin scattering is not easy to see, but it seems that it can be seen in the same way as other nonlinearities if the light is injected at high intensity. I thought that it would be possible to excite it by careful consideration of the design. I am interested in this field, so I would like to check it out. In Nature Physics 5, 276-280 (2009), something similar to the generation of optical kerr combs in modulation by optomechanics, which I discussed with Dr. Kato before, was found via Brillouin scattering.

Summary and Impressions

There were many presentations related to microcavities, and I was able to listen to many presentations in my field of interest. In particular, the special symposium on opto-mechanics provided me with useful information for considering the direction of my future research.
On the other hand, although I did not mention it in the text, I reaffirmed the importance of English proficiency. Basically, it is only Japanese who cannot speak English. I was able to listen to several presentations by Japanese speakers at the conference, and some of them could not even remember the English they were supposed to have prepared for their presentations. There were obviously some researchers who left the room when they saw that they could not speak English, which made me worry about whether Japan can maintain its international competitiveness in research and other fields. It is of course important to improve the quality of research, but it is also extremely important to improve one's English skills as a means of communicating and interacting with researchers. I have been skipping English study even before the conference, but I will consciously practice listening and speaking English from now on.