| Biography | |
|---|---|
 Prof. Zefeng Wang National University of Defense Technology (NUDT), China |
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| Title: Fiber gas Raman lasers | |
| Abstract: Fiber lasers have wide potential applications, and are increasingly replacing traditional solid state and gas lasers in many applications due to their compactness, high efficiencies, excellent beam qualities and convenient heat management. However, due to the low damage threshold, solid-core fiber lasers lack the ability to provide the same power levels as conventional gas lasers, which can reach MW levels in chemical gas lasers; Because of nonlinear effects, the spectral linewidth of light generated in silica fibers will broaden at high powers; As the number of rare earth materials is limited, only certain laser wavelengths are available; Due to the strong infrared absorption of silica fibers, it is difficult to obtain laser wavelength beyond 3 μm. Gas stimulated Raman scattering (SRS) has been demonstrated to be an effective method to obtain high-power narrow-linewidth lasers of otherwise unobtainable wavelengths, especially in the ultra-violet and mid-infrared spectral range. In traditional gas cells the effective interaction length is very short and the system can be bulky and cumbersome, limiting the applications of these lasers. The advent of anti-resonance hollow-core fibers and their properties of long effective interaction length, high optical confinement, and the possibility of control of the effective gain spectrum make it possible to develop a novel type of laser, named fiber gas Raman lasers (FGRL), which combines the advantages of both fiber and gas lasers. By properly designing the transmission bands of hollow-core fibers, selecting active gases and pump sources, FGRLs can potentially provide a wide range of emission wavelengths from the UV to the IR pumped with commercial 1μm lasers. Owing to the nature of transitions in atomic and molecular gases, FGRLs are spectrally narrow even without additional linewidth limiting measures. We have demonstrated efficient 1.1 μm, 1.5 μm, 1.7 μm, 2 μm and 3 μm FGRLs using hollow-core fibers filled with different gases, and are investigating on 4 μm band of FGRLs. Our work provides a potential simple and efficient way for high-power, narrow-linewidth fiber lasers operating at the range from visible to mid-IR by gas SRS in hollow-core fibers. | |
| Biography: Zefeng Wang is currently a professor with College of Advanced Interdisciplinary Studies, national university of defense technology (NUDT). He received the Doctor Degree in Optical Engineering from the NUDT in June 2008. He visited Bath University in UK from October 2012 to July 2014. He has published more than 80 papers as first author or corresponding author, of which 40 are included in SCI. He has been authorized 14 invention patents as first inventor. His research interests cover mainly fiber lasers, gas lasers by hollow-core fibers, fiber gratings fabrications and applications. | |
