The knowledge sharing seminar by

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Dr. (Tony) Son Tung Ha

A*STAR, Singapore

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You are most welcome to a knowledge-sharing seminar presented by Dr.  (Tony) Son Tung Ha from at the Institute of Material Research and Engineering, A*STAR, Singapore. With a friendly atmosphere, you will have a great chance to discuss and communicate with this young scientist for any potential collaborations or research experience.

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Title:

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Nanolasers based on photonic bound state in the continuum

 

Abstract: 

Dielectric nanoparticles supporting Mie-resonances at visible wavelengths are receiving significant attention from the nanophotonic community as an alternative for metal-based plasmonic counterparts. On the one hand, the dielectric particles show minimal Ohmic loss at visible wavelengths. On the other hand, they can be made with active materials tailoring great functionalities for nanophotonic devices [1]. One of the applications for such nanoparticles is as a coherent light source (a.k.a laser) by coupling with a suitable gain medium. However, a single nanoparticle supporting low-order Mie resonances (i.e., dipole, quadrupole) has a relatively low quality (Q) factor (i.e, in order of 10) and thus cannot be used alone as an optical resonator. In order to achieve a sufficiently high Q factor, engineering these resonances by means of coupling with adjacent resonances is needed. In this talk, I will present several design concepts for nanolasers based on the collective resonances of dielectric nanoantennas. The interference of collective resonances associated with the bound state in the continuum (BIC) or Van Hove singularity will be discussed based on Mie theory analysis. I will show experimentally and theoretically directional nanolasers based on two-dimensional arrays [2], one-dimensional arrays [3], and a single nanoantenna [4] made out of GaAs. In these cases, GaAs act both as resonance and as gain medium (a.k.a active nanoantenna). However, due to its poor gain characteristic, lasing can only be achieved at a cryogenic temperature (i.e., 77 K). By using a more efficient gain material such as CdSe/CdxZn1-xS nanoplatelets or InGaP multi-quantum well, room temperature lasing operation can be achieved [5, 6]. This work presents design guidelines for high-performance in-plane and out-of-plane lasers, which may find broad applications in optoelectronics.

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Biography:

Dr. (Tony) Son Tung Ha is a Principal Investigator and Deputy Head of Advanced Optical Technologies Department at the Institute of Material Research and Engineering, A*STAR, Singapore. He received Ph.D (2018) in Applied Physics from the School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore. He also received Master’s degree in Chemical Engineering from Korea Advanced Institute of Sciences and Technologies (KAIST), South Korea. Dr. Ha's current research focuses on metamaterials and their applications in flat optics, LIDAR, light-emitting diodes and nanolasers. He is also interested in strongly coupled light-matter interactions such as exciton-polariton systems and optical manipulations of single photon emitters for quantum optics. He has published over 40 scientific articles & international patents with a total citation of >3,700 and an H-index of 20. His research has been published and highlighted in top-tier scientific outlets, including Nature Nanotechnology (IF = 40.52), Nature Photonics (IF = 38.77), Advanced Materials (IF = 32.09), Light Science & Applications (IF = 20.26), ACS Nano (IF = 18.03), Nano Letters (IF = 12.26). Dr Ha has secured various competitive research grants, including the A*STAR Strategic Fund in 2021 (where he is co-principal investigator together with three other co-PIs, a total of ~S$ 400,000 for four months), the Singapore Young Individual Research Grant in 2021 (where he is sole principal investigator, ~S$ 250,000 for three years) and Singapore Programmatic Grant in 2022 (where he is co-principal investigator together with six other co-PIs, a total of ~ S$10,000,000 for four years)..

References

[1]   R. P. Domínguez, S. T. Ha, A. I. Kuznetsov, Active and tunable nanophotonics with dielectric nanoantennas, Proceedings of the IEEE, 108, 5, 749-771 (2020).

[2]   S. T. Ha, Y. H. Fu, N. K. Emani, Z. Y. Pan, R. M. Bakker, R. P. Domínguez, and A. I. Kuznetsov, Directional lasing in resonant semiconductor nanoantenna arrays, Nature Nanotechnology 13, 1042–1047 (2018).

[3]   T. X. Hoang, S. T. Ha*, Z. Y. Pan, W. K. Phua, R. P. Dominguez, C. E. Png, H. S. Chu, and A. I. Kuznetsov, Collective Mie Resonances for Directional On-chip Nanolasers, Nano Letters 20 (8), 5655-5661 (2020). *Co-first author

[4]   V. Mylnikov, S. T. Ha, Z. Y Pan, V. Valuckas, R. P. Domínguez, H. V. Demir, A. I. Kuznetsov, Lasing action in single subwavelength particles supporting supercavity modes, ACS Nano 14 (6), 7338-7346 (2020)

[5]   M. Wu, S. T. Ha*, S. Shendre, E. G. Durmusoglu, W. K. Koh, R. P. Domínguez, H. V. Demir, A. I. Kuznetsov, Lasing in Colloidal Nanoplatelets via Dielectric Mie-Resonant Bound States in the Continuum, Nano Letters 20 (8), 6005-6011 (2020). *Co-first author

[6]   S. T. Ha, R. P. Domínguez, A. I. Kuznetsov, Room-temperature multi-beam, multi-wavelength bound state in the continuum laser, Advanced Optical Materials 10 (19), 2200753 (2022).

Time: 16:00 CET (21:00 Vietnam or 22:00 Singapore time), 10th May, 2023

Zoom link:  https://lu-se.zoom.us/j/6579302725

Chairmain: Assoc. Prof. Hai Son Nguyen