CLEO 2023 Riku Imamura

2023-06-02 2024-01-23 MatsuyamaHayato

Research

CLEOPR 2023 Participation Report

5th May - 10th May, Convention Center, San Jose, USA

Third-year doctoral student Riku Imamura

Outline

CLEO (Conference on
At CLEO, he participated in and presented at the Optical Engineering, Optical Communication, and Optical
The presentations of research in a wide range of fields related to light, such as electronics, photoenergy, and photo-medicine, will be presented.
The exhibition will be held at the same time. The exhibition is also characterized by the many corporate exhibits that will be held at the same time.

2. Presentation by the presenter

Title: Passive Mode-locking Without a Saturable Absorber Using a Coupled Microresonator

Authors: R. Imamura 1 , S. Fujii 2 , A. Nakashima 1 , and T. Tanabe 1
Affiliations: 1. Department of Electronics and Electrical Engineering, Faculty of Science
Department of Physics, Faculty of
Science and Technology, Keio University.

Lecture Number: JW2A.95

Mode-locking to obtain ultrashort pulses usually requires a saturable absorber or an active
Modulation is required. In this study, we propose a completely new mode-locking method, called microcavity coupling
The authors proposed a mode-synchronization method that does not require saturable absorbers by using the
We had such a large audience that we continued to explain and ask questions from the beginning to the end of the session.
The presentations were well received. As for questions, there were many questions from microcomputer researchers.
The results of this study are as follows: (1) the actual experimental efforts, (2) the platform of the resonator, and (3) the dispersion of the resonator.
I think we were able to have a discussion that became a "good" discussion.

3. presentations attended

Title: CMOS-compatible high energy passively Q-switched laser
Author: N. Singh, et. al.
Affiliation: Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-

Synchrotron DESY, Germany

Lecture Number: STu4P.2

Presentation of passively Q-switched lasers by Franz X Kärtner's group. The foundry fabricates the SiN waveguide and sputters the gain part (Tm ion-doped Al 2 O 3 ) by itself. A waveguide-type loop mirror structure using nonlinear interference is used as a saturable absorber. They reported that they have achieved Q-switch operation in the 1880 nm band. The same laboratory gave a poster presentation across from my poster, so I was able to ask them relatively detailed questions.
　This research group had been developing an on-chip passive mode-locked laser around 2010, but concluded that the lack of gain in the waveguide structure made it difficult to improve the repetition rate. Therefore, there seems to have been no new reports for several years. However, with the emergence of foundries (especially Ligentec) that can fabricate high quality SiN waveguides, the device problem has been solved. Thus, it is becoming relatively easy to realize the idea, and not only for microcomputers but also for integrated F
It was very interesting to see the new/re-entry into the field of photonics in general.

Title: A Hertz-Linewidth Erbium Laser Based on Photonic Integrated Circuits
Author: Y. Liu, et. al.
Affiliation: EPFL
Lecture Number: Stu4P.1

This is one of the follow-up reports on erbium-doped SiN waveguides by T. J. Kippenberg of EPFL. The paper published in Science last year reported the development of a narrow linewidth laser at 50 Hz in the telecommunication wavelength band using a laser medium as an on-chip amplifier (pumped at 1480 nm). The key point is that two ring resonators form a Vernier filter, which enables narrow linewidth and wavelength sweep in the range from 1550 nm to 1590 nm. The density of the erbium-doped SiN waveguide used (1.5 × 10 20 /cm 3 ) and its amplification factor (30 dBm) are comparable to those of ordinary EDFAs, suggesting that erbium-doped fiber can now be integrated.

4. at the end

　Since this was the first international conference outside Japan since COVID-19, everything was fresh in my mind, from the food to the language I heard around me to the road signs. The most impressive thing about the conference was the large number of sessions on integrated photonics, and as if to symbolize this, Ligentec, the SiN foundry, was emphasized as a sponsor of the conference. As mentioned in the session I attended, it was an opportunity for me to experience firsthand that the high level of difficulty in device fabrication in the field of integrated photonics is becoming a thing of the past, and that new entrants or re-entrants are expected to increase in the future.
　San Jose, where the conference was held, is near Silicon Valley, and the area around the venue and the hotel was full of buildings of large corporations such as Google and Apple, which made me feel as if I was in a different world. The large meals, which are typical of the U.S.A., were also generally delicious, and combined with the cool and dry weather, it was a pleasant off-campus activity.