Title: Laser Precision Manufacturing: The resolution limit

Bio: Hong-Bo Sun received BS/PhD degrees in electronics from Jilin University, China, in 1992/1996. He worked as postdoctoral researcher at the University of Tokushima (1996-2000), assistant professor at Osaka University (2000-2006), Changjiang professor at Jilin University (2006-2017) and Tsinghua University since 2017. His research interest is ultrafast laser manufacturing. So far, he has published over 600 papers in above fields, which are cited for 40000+ times, and H factor is 102, according to ISI search report. He is CAS academician, IEEE, OSA, SPIE, COS and CSOE fellow, editor-in-chief of PhotoniX, and executive editor-in-chief of Light Science and Applications. Hong-Bo Sun received BS/PhD degrees in electronics from Jilin University, China, in 1992/1996. He worked as postdoctoral researcher at the University of Tokushima (1996-2000), assistant professor at Osaka University (2000-2006), Changjiang professor at Jilin University (2006-2017) and Tsinghua University since 2017. His research interest is ultrafast laser manufacturing. So far, he has published over 600 papers in above fields, which are cited for 40000+ times, and H factor is 102, according to ISI search report. He is CAS academician, IEEE, OSA, SPIE, COS and CSOE fellow, editor-in-chief of PhotoniX, and executive editor-in-chief of Light Science and Applications. 

Abstract: Existing nanofabrication technologies typically require tools with nanoscale feature sizes (such as cutting edge thickness, tip dimensions, or particle beam diameters) or templates to interact directly with the workpiece to achieve nanoscale resolution. In contrast, photons, as a direct processing medium, offer unique advantages over physical tools, including flexibility and the absence of wear. However, the processing precision defined by the optical diffraction limit (approximately 550 nm for visible light) needs to be improved by an order of magnitude to meet the requirements of true nanofabrication. This report introduces our research on utilizing femtosecond lasers for nonlinear manipulation of light-matter interactions, achieving three-dimensional fabrication with sub-10 nm resolution. Applications of the technology, spanning multiple fields from intelligent micro/nano-robots to photonic quantum integrated chips, will be introduced.

Title: Reducing energy consumption of data centers by novel design of VCSELs and CMOS-based drivers

Bio: Dieter Bimberg was a Professor of EE, RWTH Aachen, before assuming the Chair of Applied Physics at TU Berlin, founding the Center of NanoPhotonics. He held guest professorships at Technion, Haifa, U.C.S.B. CA, and HP in Palo Alto, CA. In 2018 he was appointed as executive director of the “Bimberg Chinese German Center for Green Photonics” at CIOMP of the CAS.
He is a member of the German Academy of Sciences, the EU Academy of Sciences, the Russian Academy of Sciences, the US Academies of Engineering and of Inventors, the National Academy of Artificial Intelligence (NAAI), the CORE Academy and Chinese Optical Society, a Life Fellow of APS and IEEE, Vice-President of the IAIA. He is recipient of important international awards, like the UNESCO Nanoscience Award, the Max-Born Award and Medal of IoP and DPG, the Nick Holonyak Jr. Award of IEEE, the MOC Award of the JSAP, the Jun-Ichi Nishizawa Award of IEEE, the Stern-Gerlach Award of DPG. He received honorary doctorates of the University of Lancaster, UK, and the St. Petersburg Alferov University.
He has authored more than 1600 papers, 71 patents and patent applications, and six books. The number of times his research works has been cited is 72,000+ and his Hirsch factor is 118.

Abstract: Since 2018 novel consumer applications like Netflix, Block Chain, LIDAR… and most recently AI, not known 2018, have led to a huge increase of internet traffic of 60%/year, much more than then originally predicted by companies like Cisco. This increased use of the internet is increasing its electrical power consumption due to increased data traffic mostly inside data centers. NVDIA announced in 10/24 AI racks consuming 1 MW. New data centers have crossed the 500 MW level. Predictions e.g by IEA Paris or the US government show that the energy consumption will rise in a short time to an extent not further tolerable.
New device designs are developed by us, focusing on energy-efficiency of data traffic at all hierarchy levels combined with larger data rates. Vertical-cavity surface-emitting lasers (VCSELs) for 400+ Gbit/s single fiber data transmission across OM5 multimode fiber with a record energy to bit rate ratio (EDR) of less than ~90 fJ/bit @ 100 Gbit/s at 940 and 1060 nm nm wavelengths are presented. Photon lifetime management is a new key to adopt overall energy consumption to the bit rate of the data traffic (e.g. 25 Gb/s, 50 Gb/s...) ^[1,2].
Novel designs of Vertical-Cavity Surface-Emitting Lasers (VCSELs) are presented leading to a strong reduction of thermally induced band gap shift as a function of current and of the series resistance. In our simplest approach (called MUHA 1) blind holes or rings are dry etched into standard devices and then filled with gold resulting in both an effective heat drain technology and electrical shunt, reducing the device series resistance ^[3]. A different, more sophisticated approach (called MUHA 2) uses the dry etched holes or rings to oxidize the apertures ^[4]. The shape and size of the aperture now depend on the arrangement of holes, opening the way for polarized emission without etching gratings. First results to validate larger output power, rollover current for single mode emission devices, and reduced series resistance are presented for both cases. Finally, multi-aperture VCSELs (called MAVs) based on positioning multiple MUHA 2 in one high power pseudo single-mode emitter are realized ^[5].
Given the progress in reducing EDR of VCSELs below 100 fJ/bit presented here, the next focus should be on the EDR of the driver and the complete module. EDR of commercial drivers is presently at least 10 times larger than that of the VCSELs. Gerfers et al. ^[6] developed a new driver approach based on ultra-fast CMOS ICs allowing also pre-emphasis showing radically reduced EDR. First results of integration with our VCSELs will be presented. Our VCSELs can be released from the substrate and directly deposited on the driver circuit. 
Thus, complete front-end modules are expected to allow for the first time much improved energy efficiency of Tb/sec dense wavelength multiplexing across distances of several 100 m to 1 km in data centers.
[1] G. Larisch, R. Rosales, and D. Bimberg, , IEEE J. Select. Topics in Quantum Electronics, 25, 1701105 (2019) and G. Larisch, S. Tian, D. Bimberg, Optics Express 28, 18331 (2020)
[2] Bin Wang, ….Sicong Tian, Hui Li, Cun-Zheng Ning, and Dieter Bimberg “Polarization Discrimination and Signal-Integrity Optimization for 1060 nm Elliptical-Aperture Vertical-Cavity Surface-Emitting Lasers”, Optica 2025 under consideration
[3] M A Maricar, S. Tian, and D. Bimberg, patents in the EU, US and CN, e.g. EP 23199013,
[4] G. Larisch, S. Tian, and D. Bimberg, patents in the EU, US and CN, e.g. EP 3 961 829
[5] G. Larisch, S. Tian, and D. Bimberg, patents in the EU. US and CN e.g. EP 4007092
[6] N. Kioulos,…Asian ISCAS 2026, Shanghai

Title: Ultrafast Electron Microscopy–Advances and Results

Bio: Peter Baum is a professor of physics at University of Konstanz, Germany. He received his PhD in 2005 from Ludwig-Maximilians-Universität München, worked as a postdoctoral scholar with Prof. Zewail at Caltech and was a junior group leader with Prof. Krausz at the Max-Planck-Institute of Quantum Optics. His current research in Konstanz focuses on the interaction of light and matter at ultimately small dimensions of space and time, using electron pulses under light-cycle control. In his spare time, he listens to metal music and goes skiing, swimming or surfing.

Abstract: All processes in materials, nanostructures and devices are on a fundamental level defined by electronic and atomic motion from initial to final conformations. Our approach for a direct, real-space visualization is pump-probe electron microscopy and diffraction with single-electron wavepackets under the control of laser light ^[1]. The resulting few-femtosecond and attosecond time resolution allows to see almost any light-matter interaction or structural dynamics on fundamental scales in space and time ^[2-6]. We report recent technology developments ^[2] and how they provide insight into phase transitions of strongly correlated materials ^[3], ultrafast electronics at terahertz frequency ^[4], chiral phonons in magnetic switches ^[5], free-electron quantum phenomena ^[2] and attosecond dynamics in optical nanomaterials ^[6], concluding with a perspective on what is yet to come.[1] C. Kealhofer, W. Schneider, D. Ehberger, A. Ryabov, F. Krausz, P. Baum, Science 352, 429 (2016).
[2] Y. Fang, J. Kuttruff, D. Nabben, P. Baum, Science 385, 183-187 (2024).
[3] P. Baum, D.-S. Yang, A. H. Zewail, Science 318, 788 (2007).
[4] A. Ryabov and P. Baum, Science 353, 374 (2016).
[5] S. R. Tauchert, M. Volkov, D. Ehberger, D. Kazenwadel, M. Evers, H. Lange, A. Donges, A. Book, W.Kreuzpaintner, U. Nowak, P. Baum, Nature 602, 73 (2022).
[6] D. Nabben, J. Kuttruff, L. Stolz, A. Ryabov, P. Baum, Nature 619, 63 (2023).