講演情報
[7a-N204-4]Ultrafast vortex beams for chiral selectivity
〇Yuchieh Lin1, Katsumi Midorikawa1, Yasuo Nabekawa1 (1.RIKEN)
キーワード：
optical vortex、ultrafast optics、chiral selectivity
Few-cycle optical vortex (OV) pulses with helical wavefronts are valuable tools for strong-field phenomena such as high-order harmonic generation (HHG), filamentation, and supercontinuum generation. In the sub-cycle regime, precise control of the spatiotemporal electric field becomes essential, particularly for interactions sensitive to the instantaneous field. We report a carrier-envelope phase (CEP)-controllable OV source in the short-wave infrared (SWIR) regime, delivering 4.7 fs pulses -- equivalent to 0.9 optical cycles at a center wavelength of 1.54 μm -- with over-octave bandwidth spanning 0.9–2.4 μm. The OV pulses are produced by converting sub-cycle Gaussian pulses from a SWIR optical parametric amplifier into vortex beams using an achromatic Sagnac interferometer. The topological charge 1 is confirmed via spiral interference patterns. Full-field reconstruction using two-dimensional shearing interferometry verifies that the pulse duration is near the transform limit. Crucially, CEP tuning enables control of the azimuthal phase, allowing active manipulation of the spiral wavefront. This intense, CEP-stable OV source enables new capabilities in chirality-sensitive light-matter interactions, including enantioselective spectroscopy. We will present recent results demonstrating the use of this source for distinguishing chiral samples, highlighting its potential for next-generation attosecond and chiral photonics.