News & Gallery
2025
[Jan 2025] Invited Talk in Photonics West, San Francisco, USA
[Jan 2025] Early Career Editorial Advisory Board of APL Photonics, AIP Publishing
I'm excited to join the Board of APL Photonics journal! Each year, five board members are selected for two-year term in a highly competitive application process. APL Photonics recognizes excellence of early career researchers and hears the perspectives of future leaders in the field. Thus, I will work on the scientific and educational content and editorial policies of the journal for 2025-2026.
2024
[Nov 2024] Publication in Optics Express
Deep-red planar waveguide laser operation of Eu:KY(WO4)2 layers
https://doi.org/10.1364/OE.537598
[Oct 2024] Publication in Advanced Materials Technologies
[Oct 2024] Invited Talk in Joint Workshop on Structured Light and Materials
I gave an invited talk at Joint Workshop on Structured Light and Materials in Osaka, Japan. The two-day workshop was held at Osaka Metropolitan Univ. I would like to thank the organizers, Prof. Takashige Omatsu (Chiba Univ, Japan) and Prof. Yung-Fu Chen (National Yang Ming Chiao Tung Univ, Taiwan). It was a valuable time to meet many colleagues and discuss various topics on structured matter!
[Oct 2024] Optica Laser Congress (Advanced Solid State Lasers Conference) in Osaka, Japan
I attended the ASSL conference in Osaka, Japan and was pleased to give two presentations on my recent works: [Watt-Level Er:YAlO3 Waveguide Laser at 2920 nm] and [Highly-efficient Tm:LiYF4 Waveguide Laser Passively Q-switched by Carbon Nanotubes].
[Oct 2024] PhD Thesis Committee Member for Dr. Sami Slimi
It was a great honor to serve as a PhD committee member for Dr. Sami Slimi at Universitat Rovira i Virgili. I enjoyed the thesis and the defense in Tarragona, Spain. Thank you for the invitation and congratulations to his supervisors, Prof. Xavier Mateos and Prof. Rosa Maria Solé! I would also like to thank the other committee members, Prof. Magdalena Aguiló and Dr. Victor Llamas Martínez, for working with me!
[Oct 2024] Invited Seminar at URV in Tarragona, Spain
[Aug 2024] EPS-QEOD Europhoton Conference in Vilnius, Lithuania
I attended the 11th Europhoton conference organized by European Physical Society Quantum Electronics and Optics Division (EPS-QEOD) in Vilnius, Lithuania and presented [Continuous-wave and SESAM mode-locked 2.3-µm Tm:LiYF4 lasers: Upconversion pumping at 1.45 µm] in the Session TH-4: Lasers at 2 µm and beyond. This result shows the high-performance 2.3-µm Tm lasers from the original 1.45-µm high-brightness upconversion pumping.
[Aug 2024] Publication in Applied Physics Letters
Our work on mid-infrared Er waveguide lasers was published in Applied Physics Letters 125, 081101 (2024). The results show the highest output power for rare-earth-doped MIR waveguide lasers and the lowest laser threshold for Er MIR waveguide lasers. This is attributed to the high optical quality of the liquid-phase-epitaxial Er:LiYF4 layer, which was firstly demonstrated in a MIR waveguide laser. The high available doping ratio of the epitaxy allows multiple laser lines to be obtained due to the high inversion ratio in the quasi-monolithic cavity with reduced water vapor absorption.
[Jul 2024] OPTIQUE 2024 in Rouen, France
I attended the OPTIQUE conference (every 2-year domestic conference organized by SFO -French Optical Society) held in Rouen, Normandie and presented my work titled [GaSb-based SESAM mode-locked femtosecond 2309-nm Tm:LiYF4 laser] in the Session 8-C: JNCO-Lasers Solides. More information is available in Optics Express 32(9), 15093 (2024).
It was a great week to meet many of my colleagues and network with new people. We enjoyed the city and had a nice time!
[Jul 2024] Publication in Optics and Laser Technology
Our work on noise characterization of low-jitter GHz mode-locked waveguide lasers was published in Optics and Laser Technology 179, 111412 (2024). This research was done in collaboration with Prof. Jungwon Kim's group at KAIST (Korea), Prof. Xavier Mateos at Universitat Rovira i Virgili (Spain), and Prof. Javier Rodríguez Vázquez de Aldana's group at Univ of Salamanca (Spain).
The results include experimental demonstration of high multi-GHz repetition-rate mode-locking with low timing jitter and a full theoretical analysis of the phase noise spectra including relaxation oscillation depending on the cavity condition (repetition rate, loss, etc).
[May 2024] Invited Seminar at CIMAP
I gave a seminar talk at Centre de Recherche sur les Ions, les Matériaux et la Photonique Laboratory. The presentation titled [Integration of waveguides and nanomaterials towards miniaturized pulsed lasers] was mainly about my previous research on pulsed waveguide lasers done in Korea. I appreciate all the audience for great discussion and questions!
[Apr 2024] Research Visit in Berlin, Germany
I had a three-week research visit at Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy (MBI) in Berlin, Germany to collaborate with Dr. Uwe Griebner. I worked on post-compression experiments of a multi-mJ 5-µm OPCPA (optical parametric chirped-pulse amplifier) system.
[Apr 2024] Publication in Optics Express
Our work on upconversion-pumped 2.3-µm SESAM mode-locked Tm lasers was published in Optics Express 32(9), 15093 (2024). This was done in collaboration with Prof. Ammar Hideur's group at CORIA lab (France) and Prof. Ursula Keller's group at ETH Zürich (Switzerland).
The results employing high-brightness 1.04-µm upconversion pumping and GaSb-based SESAM show a significant development of ultrafast Tm lasers representing the first femtosecond SESAM mode-locked Tm laser at 2.3 µm and the record-high output power from a 2.3-µm Tm laser.
[Mar 2024] Optica High-Brightness Sources and Light-Driven Interactions Congress (Mid-Infrared Coherent Sources) in Vienna, Austria
I attended the MICS conference organized by Optica in beautiful Vienna, Austria and presented my recent work titled [Planar Er:LiYF4 Waveguide Laser at 2.8 μm] in the Session MTu3C: Mid-IR and THz Coherent Sources II. More information is available in Applied Physics Letters 125, 081101 (2024). Many thanks to all those who attended and had a fruitful discussion. It was a nice time to see my dear colleagues!
[Feb 2024] Research Visit in Rouen, France
I spent a week on a research visit at Complexe de Recherche Interprofessionnel en Aérothermochimie (CORIA) laboratory, CNRS, Université de Rouen Normandie. We employed an original 1.45-µm upconversion pumping in 2.3-µm Tm:LiYF4 solid-state lasers. Efficient continuous-wave and femtosecond SESAM mode-locked operation were obtained.
I presented the results at the Europhoton 2024 conference and a journal paper is currently in preparation.
2023
[Dec 2023] Publication in Current Optics and Photonics
Our work on Cr:ZnS mode-locked lasers with transmitting graphene saturable absorber was published in Current Optics and Photonics 7(6), 738 (2023). It was done in collaboration with Dr. Won Bae Cho at ETRI (Korea).
The results using graphene saturable absorber transferred on ZeSe substrate with high nonlinearity show much shorter pulses compared to the case of graphene on CaF2 by control of group-delay dispersion.
[Nov 2023] Research Visit in Rouen, France
I had a one-week research visit to collaborate with Complexe de Recherche Interprofessionnel en Aérothermochimie (CORIA) laboratory, CNRS, Université de Rouen Normandie. I worked on the dispersion management of 2.3-µm SESAM mode-locked Tm:LiYF4 solid-state lasers with 1.04-µm upconversion pumping. Soliton femtosecond pulses were achieved by additional LiYF4 crystals as dispersive Brewster's plates.
I presented the results at the 2024 OPTIQUE Normandie conference (SFO) and the journal paper was published in Optics Express 32(9), 15093 (2024).
[Nov 2023] Association des Scientifiques Coréens en France (ASCoF) Fall Conference
I attended the 2023 ASCoF (Association of Korean Scientists in France) Fall Conference held in Paris. It was a great time to network with Korean scientists working in France and share our professional fields. Hope to see you again at future conferences and the Europe-Korea Conference on Sci and Tech.
[Sep 2023] Invited Talk in European Optical Society Annual Meeting (EOSAM) 2023
I gave an invited talk at EOSAM 2023 in the gorgeous city, Dijon. My presentation titled [Crystalline waveguides with carbon nanomaterials for miniaturized pulsed lasers] was in the Session TOM5 S04: Optical materials and lasers.
[Sep 2023] Starting a new position as a CNRS Postdoctoral Fellow at Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP), UMR 6252 CEA-CNRS-ENSICAEN, Université de Caen Normandie
[Aug 2023] Seal of Excellence, European Commission
Seal of Excellence certificate was awarded to my project submitted to the Horizon Europe MSCA Postdoctoral Fellowship 2022. This recognizes a high scientific quality proposal in a highly competitive evaluation process and is a quality label awarded to outstanding projects that achieved a high score in the application.
[Jul 2023] POSCO Science Fellows Symposium in Physics, POSCO TJ Park Foundation
The annual POSCO Science Fellows Symposium in Physics was held in Seoul. I presented my previous works and fellowship project with a title of [Compact Pulsed Lasers Integrated with Nanomaterial-based Photonic Devices]. It was a very constructive time to discuss with the esteemed fellows. Looking forward to see you again next time!
[Jun 2023] CLEO/Europe-EQEC 2023 in Munich, Germany
It was a wonderful week in Munich, enjoying great times with many familiar faces and meeting new colleagues! Hope to see you all again soon! It was my second visit to Munich in 4 years and I also visited Regensburg near Munich.
My presentation was in the Session CA-9: Waveguide lasers and shared my recent results on the characterization of noise spectra in gigahertz-level mode-locked waveguide lasers. More information is available in Optics and Laser Technology 179, 111412 (2024). Thanks to all those who attended and had a great discussion!
[May 2023] The 22nd Advanced Lasers and Their Applications (ALTA) in Jeju Island
I attended the 22nd ALTA conference (organized by the Quantum Electronics Division, Optical Society of Korea) in Jeju Island. My presentation was about the result on fundamentally mode-locked femtosecond operation of Yb:KLuW waveguide lasers at multi-gigahertz repetition rates. More information is available in Photonics Research 10(11), 2584 (2022).
P.S. I experienced my first flight cancellation due to weather conditions on my way back to Daejeon after the conference. Thus, I stayed an extra night in Jeju to wait for an alternative flight and was assigned to a flight to Seoul the next day.
[Mar 2023] MSCA-COFUND Postdoctoral Fellowship, European Union & Région Normandie
My project [ChiEF: Chip-scale Erbium Fluoride Mid-infrared Ultrafast Laser] has been selected for the Marie Skłodowska-Curie Actions (MSCA) COFUND: WINNING Normandy Fellowship funded by the European Union and the Région Normandie! The 2-year fellowship will support a research grant of 87,000 euros per year.
[Feb 2023] Commencement & Doctoral Hooding Ceremony, KAIST
I received my PhD degree in Physics at KAIST! I attended KAIST Commencement and Doctoral Hooding Ceremony of College of Natural Sciences.
[Feb 2023] Global Leadership Award (Creativity), KAIST
At the Celebration of KAIST's 52nd Founding Anniversary, I received the award from the President of KAIST. It recognized outstanding creativity according to the core values of KAIST: Creativity, Challenge, and Care. I was recommended as a nominee by the Head of Dept of Physics based on my diverse research achievements and international recognitions.
[Feb 2023] Society of Global PhD Fellows Symposium & Alumni Night, National Research Foundation of Korea
As a Board Committee Member of the Fellows, I organized and attended the Symposium & Alumni Night supported by the National Research Foundation of Korea. It was nice to meet the Fellows from broad professional fields without face masks. Hope to see them again soon!
2022
[Dec 2022] Optica Laser Congress (Advanced Solid State Lasers Conference) in Barcelona, Spain
I had a great time to meet and discuss with my dear colleagues in beautiful Barcelona! I presented the result on dynamically controllable Q-switched operation of beam-splitter-type waveguide laser. More information is available in Laser & Photonics Reviews 16(4), 2100501 (2022), highlighted as an inside front cover article.
[Sep 2022] POSCO Science Fellowship, POSCO TJ Park Foundation
My proposal [Compact pulsed waveguide lasers with nanocarbon photonics] has been selected for the POSCO Science Fellowship funded by the POSCO TJ Park Foundation! The fellowship supports young professors and postdoctoral researchers working in Korea. I have been finally accepted after the document screening and interview (8 for postdocs, acceptance rate <10%). The 2-year fellowship will support a research grant of 70,000,000 KRW. [Press release in Korean] [List of Fellows in Korean]
[Sep 2022] The 9th Annual Global PhD Fellows Conference, National Research Foundation of Korea
As a Conference Chair, I organized and attended the annual conference supported by National Research Foundation of Korea. There were valuable presentations on diverse topics from the Fellows. I gave an opening remark as a Conference Chair and spent a happy time with my dear colleagues!
[Aug 2022] The 15th CLEO Pacific Rim in Sapporo, Japan
[Jul 2022] KAIST Optics Group Student Poster Competition, KAIST Cross-generation Collaborative Lab
