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ENS Cachan - Laboratoire de photonique quantique et moléculaire

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Nano_imaging and Nano_fabrication

Components and Technology for photonics

Among plenty of techniques proposed to realize photonic structures, direct laser writing (DLW) has been considered as an ideal one to create any desired submicrometric structure. Particularly, we have recently proposed and demonstrated a simple and low-cost method called low one-photon absorption (LOPA) DLW, which benefits the advantages of both one-photon absorption (OPA) and two-photon absorption (TPA) techniques, allowing us to fabricate arbitrary 2D and 3D submicro-structures. The LOPA fabrication technique is based on the use of an excitation laser with the wavelength located near the edge of the absorption band of the photoresist used. With this low absorption, the light beam can propagate deeply inside the material. By using a microscope lens of high numerical aperture, the laser beam is focused into small region with a very high intensity, which compensates for the low absorption of the photoresist. By scanning the focusing spot, any sub-wavelength structure can be created via local photopolymerization process. 1D, 2D, and 3D arbitrary structures, with sizes as small as 100 nm, have been fabricated using SU8 photoresist and a continuous-wave laser at 532 nm-wavelength with only a few milliwatts. Figures 1(a,b) illustrate the working principle of LOPA-based DLW technique and an example of fabricated 3D structures.

Furthermore, we have recently demonstrated that by using this LOPA-based DLW, and with a double-step process, it is possible to address most kinds of nanoparticles and to precisely embed them into desired polymeric photonic structures. Figures 1(c,d) show a 2D structure containing a single gold nanoparticle.

LOPA-based DLW

Figure 1 : (a) Experimental setup of LOPA-based DLW. (b) Example of fabricated 3D woodpile structure. (c) A 2D photonic structure containing a single nanoparticle realized by LOPA technique. (d) Fluorescent image of corresponding structure shown in (c).


  1. Thi Huong Au, Duc Thien Trinh, Quang Cong Tong, Danh Bich Do, Dang Phu Nguyen, Manh-Huong Phan, Ngoc Diep Lai, Direct Laser Writing of Magneto-Photonic Sub-Microstructures for Prospective Applications in Biomedical Engineering, Nanomaterials 7(5), 105 (2017).
  2. Quang Cong Tong, Mai Hoang Luong, Thi Mo Tran, Jacqueline Remmel, Minh Thanh Do, Duy Manh Kieu, Rasta Ghasemi, Duc Tho Nguyen, Ngoc Diep Lai, Realization of Desired Plasmonic Structures via a Direct Laser Writing Technique, Journal of Electronic Materials 46, 3695 (2017).
  3. Dam Thuy Trang Nguyen, Thi Huong Au, Quang Cong Tong, Mai Hoang Luong, Aurelien Pelissier, Kevin Montes, Hoang Minh Ngo, Minh Thanh Do, Danh Bich Do, Duc Thien Trinh, Thanh Huong Nguyen, Bruno Palpant, Chia Chen Hsu, Isabelle Ledoux-Rak, Ngoc Diep Lai, Coupling of a single active nanoparticle to a polymer-based photonic structure, Journal of Science: Advanced Materials and Devices 1, 18-30 (2016).
  4. Dam Thuy Trang Nguyen, Quang Cong Tong, Isabelle Ledoux-Rak, and Ngoc Diep Lai, One-step fabrication of submicrostructures by low one-photon absorption direct laser writing technique with local thermal effect, J. Appl. Phys. 119, 013101 (2016).
  5. Quang Cong Tong, Dam Thuy Trang Nguyen, Minh Thanh Do, Mai Hoang Luong, Bernard Journet, Isabelle Ledoux-Rak, and Ngoc Diep Lai, Direct laser writing of polymeric nanostructures via optically induced local thermal effect, Appl. Phys. Lett. 108, 183104 (2016).
  6. Mai Trang Do, Dam Thuy Trang Nguyen, Hoang Minh Ngo, Isabelle Ledoux-Rak, and Ngoc Diep Lai, Controlled coupling of a single nanoparticle in polymeric microstructure by low one-photon absorptionbased direct laser writing technique, Nanotechnology 26, 105301 (2015).
  7. Qinggele Li, Isabelle Ledoux-Rak, and Ngoc Diep Lai, Influence of incident beam polarization on intensity and polarization distributions of tight focusing spot, Adv. Device Mater. 1, 4-10 (2015).
  8. Qinggele Li, Mai Trang Do, Isabelle Ledoux-Rak, and Ngoc Diep Lai, Concept for three-dimensional optical addressing by ultralow one-photon absorption method, Opt. Lett. 38, 4640-4643 (2013).
  9. Mai Trang Do, Thi Thanh Ngan Nguyen, Qinggele Li, Henri Benisty, Isabelle Ledoux-Rak, and Ngoc Diep Lai, Submicrometer 3D structures fabrication enabled by one-photon absorption direct laser writing, Opt. Express 21, 20964-20973 (2013).
  10. Ngoc Diep Lai, O. Faklaris, D. Zheng, V. Jacques, H.-C. Chang, J.-F. Roch, F. Treussart, Quenching nitrogen-vacancy center photoluminescence with infrared pulsed laser, New J. Phys. 15, 033030 (2013).
  11. Ngoc Diep Lai, D. Zheng, F. Treussart, J.-F. Roch, Optical determination and magnetic manipulation of single nitrogen-vacancy color center in diamond nanocrystal, Adv. Nat. Sci.: Nanosci. Nanotechnol. 1, 015004 (2010).


Ngoc Diep Lai
Associate Professor


Ngoc Diep Lai (Associate Prof.)
Dam Thuy Trang Nguyen (PhD student)
Au Thi Huong (PhD student)
Tong Quang Cong (PhD student)
Do Mai Trang (PhD student)
Qinggele Li (
PhD student)
Luong Mai Hoang (M2)
Tran Thi Mo (M1)
Kieu Duy Manh (M2)

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