CLEO 2020 Kouki Yoube


CLEO 2020 Participation Report

11-15 May 2020, Online

1st year master's student Kouki Yoube

About CLEO2020

CLEO is an international conference on laser science organized by The Optical Society (OSA), American Physical Society (APS), and IEEEPhotonics Society. The conference is usually held in San Jose, but this year the conference was held online due to the new coronavirus infection (COVID-19). The online conference was not always smoothly conducted due to poor connectivity and recording environment. However, the advantages of holding the conference online, such as the fact that the conference was free of charge and anyone could attend, and the fact that the recordings could be viewed at a later date, were demonstrated.

2. Presentation by the presenter

Title: Coupling of Whispering Gallery Mode with Silicon Photonic Crystal
Presenter: Koki Yube
Affiliation: Keio University
Presentation No.: SM1J.4(Mon, May11th)

Efficient coupling of silicon photonic crystal waveguides and resonators with silicatroid resonators, which are Whispering Gallery Mode (WGM) resonators, is presented. The application potential of the coupled system of resonators with asymmetric Q-values was reported. The presentation was given as a live presentation. In case of technical problems such as poor connection, we broadcasted the video recording. Although I was a little concerned about my language ability, I did not have any trouble understanding the questions because I could check them in the text. As for the questions, many of them were about whether it is possible to fabricate a WGM resonator with high Q-value on the same chip as photonic crystals. I felt that many of the questions were basic questions that could be anticipated. Due to the coronavirus, we were able to complete the live presentation without any problems because we were accustomed to using web conferencing systems such as Zoom and Webex for meetings in our laboratory and for lectures in round-table discussions.

3. presentations attended

Title: Non-Hermitian Topological Light Steering
Presenter: Han Zhao
Affiliation: University of Pennsylvania
Presentation No.: FTh1B.5(Thu,May14th)

A method for controlling light flow on demand by combining a non-Hermite system and a topological system is presented. The topological system consists of a coupled micro-ring resonator system of InGaAsP, where new topological states emerge at the boundary between gain and loss regions by local optical pumping. Since topological optical paths can be flexibly reconfigured, applications such as optical routing are being considered.

Title: PT-symmetric topological edge-gain effect
Presenter: Alex Y. Song
Affiliation: Stanford University
Presentation No.: FM2A.2(Mon,May11th)

Early studies of topological systems assumed a Hermite Hamiltonian, but recently there has been interest in the topological properties of non-Hermite (gain/loss present) Hamiltonians. It is now clear that in such systems, even when pumping the entire system, the bulk is nonamplified and only the edges exhibit gain and loss. Possible applications include topological lasers, where pumping the entire structure is now possible, eliminating the need for selective pumping that has been necessary in previous studies.

Title: On-chip Q-factor greater than 1 billion
Presenter: Lue Wu
Affiliation: California Institute of Technology
Presentation No.: SW3J.7(Wed,May13th)

The Q-value on the order of the ninth power of 10 was achieved in an on-chip silica wedge resonator. Undercut to the buckling limit. Each of the optimizations has resulted in the following improvements: 1. lower XeF2 dry etch time, lower unintended silica etching 2. more stable fabrication 3. lower bulk stress, removal of OH groups, denser thermal oxides 4. less silicon residue, lower wedge stresses 5. less silicon residue, less silica etching, less silica etching, less silica etching, less silica etching, less silica etching, less silica etching. 4. lower silicon residues, lower wedge stresses. I did not find it interesting academically, but I felt that achieving high Q-values through careful fabrication was highly important.