Welcome to LEAL

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  Laser Engineering & Applications Laboratory (LEAL), led by Dr Yoonchan Jeong, explores the outer reaches of photonics science and technology, especially, in high-power and high-energy regimes. The research foci are on developing innovative lasers and photonic systems and also on providing novel and powerful solutions to the related applications. The main research interests include Generation of High-Power / High-Energy Photons, Photon-Photon / Photon-Electron / Photon-Phonon Energy Conversions, Photon-Molecule Interactions, and related many interesting applications, such as Lidar, Laser Sonar, Remote Sensing, Space Optical Communication, Display, Nano-Biomedical applications, Technology Textiles, etc.

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News

  • The project "Core technology for high-power low-loss fiber laser" by our professor Y. Jeong collaborating, has been announced as "Top 100 Progress in National R&D 2017."

  • Our student Hansol Kim received the best paper award from Photonics conference 2017.

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  • LEAL awards ceremony was held on Oct. 20.


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  • Our lab got a new student Juhwan Kim.

  • Research professor Luis Alonso Vazquez-Zuniga got a new job at Calmar Laser and received a certification of apreaciation from Y. Jeong.

  • Our student S. Lee received the best student paper award for COOC 2016 conference.

  • Professor Jeong received the best lecturer award for Spring 2015.

  • Our student Y. Kwon received the best student paper award for COOC 2014 conference.

  • "Adaptive broadband continuum source at 1200-1400nm based on an all-fiber dual-wavelength master-oscillator power amplifier and a high-birefringence fiber" is posted to the OCT news article(Link to the article).

     

  • "Adaptive broadband continuum source at 1200-1400nm based on an all-fiber dual-wavelength master-oscillator power amplifier and a high-birefringence fiber" is also selected as the paper of the Virtual Journal of Biomedical Optics(Link to the journal website)

     

  • Our student K.Park received the best student paper award for ALTA 2013 conference.

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Metallic Fresnel zone plate implemented on an optical fiber facet for super-variable focusing of light


H. Kim, J. Kim, H. An, Y. Lee, G. Lee, J. Na, K. Park, S. Lee, S. Lee, B. Lee, and Y. Jeong.

Vol 25, no. 24, pp. 30290-30303, (2017), Optics Express

 

 Abstract : We propose and investigate a metallic Fresnel zone plate (FZP/MFZP) implemented on a silver-coated optical fiber facet for super-variable focusing of light, the focal point of which can be drastically relocated by varying the wavelength of the incident light. We numerically show that when its nominal focal length is set to 20 μm at 550 nm, its effective focal length can be tuned by ~13.7 μm for 300-nm change in the visible wavelength range. This tuning sensitivity is over 20 times higher than that of a conventional silica-based spherical lens. Even with such high tuning sensitivity with respect to the incident wavelength change, the effective beam radius at the focal point is preserved nearly unchanged, irrespective of the incident wavelength. Then, we fabricate the proposed device, exploiting electron- and focused-ion-beam processes, and experimentally verify its super-variable focusing functionality at typical red, green, and blue wavelengths in the visible wavelength range, which is in good agreement with the numerical prediction. Moreover, we propose a novel MFZP structure that primarily exploits the surface-plasmon-polariton-mediated, extraordinary transmission effect. For this we make all the openings of an MFZP, which are determined by the fundamental FZP design formula, be partitioned by multi-rings of all-subwavelength annular slits, so that the transmission of azimuthally polarized light is inherently prohibited, thereby leading to super-variable and selective focusing of radially polarized light. We design and fabricate a proof-of-principle structure implemented on a gold-coated fusedsilica substrate, and verify its novel characteristics both numerically and experimentally, which are mutually in good agreement. We stress that both the MFZP structures proposed here will be very useful for micro-machining, optical trapping, and biomedical sensing, in particular, which invariably seek compact, high-precision, and flexible focusing schemes.

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 View full text article_journal website link(pdf)