CLEO 2020 Koshiro Wada


CLEO 2020 Participation Report

11-15 May 2020, Online

Koshiro Wada, 1st year master's student

About CLEO2020

This international conference was held on the above schedule. The content of the conference was especially related to optics, and the number of invited lectures was remarkable. I thought it was very good that the conference was held online, so that the lectures could be attended free of charge once pre-registration was completed, and that the presentations were recorded and could be viewed at a later date. I felt that these problems were caused by the online nature of the event.

2. Presentation by the presenter

Title: Efficient Kerr comb generation aligned with ITU-T grid for DWDM telecom applications
Presenter: Koshiro Wada
Affiliation: Keio University
Presentation No.: FM2R.4 (Mon, May 15th)

The presentation focused on the generation of an MI comb with a grid spacing of 25 GHz on the ITU-T grid using a magnesium fluoride crystal microcavity, and its potential application to DWDM optical communications by controlling the FSR and dispersion of the crystal resonator using precision machining. The presentation method was Dynamic e-poster, and the presentation was made by oral presentation on the day of the meeting unless there was a technical problem, although a movie with voice was submitted in advance. The online presentation method is advantageous in that the presenters can check the manuscript at any time, so they can give their presentations in a relaxed manner. Many of the questions were related to the FSR accuracy of crystal resonators by precision machining.

3. presentations attended

Title: Stable Dissipative Kerr Solitons in an AlGaAs Microresonator Through Cryogenic Operation
Presented by: Gregory Moille
Affiliation: National Institute of Standards and Technology
Presentation No.: SW4J.1 (Wed 13, May)

Comprehensive presentation on the stabilization of solitons in ring resonators made of III-V alloys (Al0.2Ga0.8). Group III-V alloys have attracted attention as a new platform for soliton generation because their nonlinear refractive index is larger (35~260) than that of conventional ring resonators (0.3~2.4) and nonlinear absorption is less likely to occur. However, the Q-value is not sufficient for soliton generation, and the thermo-optic coefficient is high, etc. With the improvement of fabrication techniques, the highest Q-value of more than 1.5×106 has been produced, and soliton stepping has been observed, but stabilization has not been achieved yet. In this presentation, after theoretically verifying that a decrease in the thermo-optic coefficient leads to an increase in the length of the soliton step, we confirmed that the thermo-optic coefficient decreases linearly with decreasing temperature in silicon nitride and that there is no change in resonator characteristics (Q value, Pth, FSR, Dint) at very low temperatures ( 7~60 K), and that the soliton step length increases at ultra-low temperatures (7~60 K). This is in good agreement with LLE simulations performed at T=0 K. We then performed similar experiments for III-V alloys (AlGaAs) and confirmed that the thermo-optic coefficient decreases dramatically below 30 K. The soliton generation at such low temperatures was also confirmed experimentally.

Title: Multistability-Enabled Complex Soliton Dynamics in a Bichromatically Driven Optical Microresonator
Presenter: Wenle Weng
Affiliation: Ecole Polytechnique Federale de Lausanne
Presentation No.: FTh3J.5 (Thu 14, May)

The presentation deals with the multistability of solitons, especially the switching between soliton collision and soliton binding. There are other types of soliton multistability, such as soliton crystal and soliton oscillation, but their physics have not yet been analyzed in detail. In the conventional method, soliton collision and soliton binding are caused by using sidebands generated by one CW laser and a phase modulator for one resonant mode of a crystal resonator, whereas in the present method, two CW lasers are used for two resonant modes belonging to the same mode family. In the present method, two CW lasers are used to induce soliton collision and soliton binding in two resonant modes belonging to the same mode family, and the switching is performed by controlling the group velocity mismatch by detuning.