AI 中文总结
本研究观测到氢中受激后向拉曼放大产生的相对论光栅上的斜布拉格-多普勒反射，该效应可作为超高频布拉格单元移频器，为多领域研究开辟新机遇。
AI 中文摘要
我们首次报道了相对论“布拉格-多普勒”反射的观测结果，该反射发生在光束入射到接近光速运动的细周期相位光栅时。该光栅通过种子后向受激拉曼散射在充氢空芯光纤中产生，形成频率为125 THz、波长299 nm、运动速度约为c/8的强分子振动相干波。当以广义布拉格角对该光栅进行斜向探测时，会产生反射光束，其多普勒频移为125 THz。该效应还具有单向性，因为当探测光束反向时，相位匹配会被严重破坏，因此可视为超高频布拉格单元移频器。氢的宽透明窗口允许仅通过调节入射角实现从可见光到真空紫外波段辐射的移频。该研究结果为相干波动力学的时空研究、深紫外及真空紫外等难进入光谱区域的频率转换，以及单光子的量子态保持频率转换开辟了新机遇。
英文摘要
We report the first observation of relativistic "Bragg-Doppler" reflection, which occurs when a light beam is incident on a fine-period phase grating moving at close to the speed of light. The grating is created in hydrogen-filled hollow-core fibre by seeded backward stimulated Raman scattering, which creates an intense coherence wave of molecular vibrations at 125 THz, with wavelength 299 nm, moving at ~c/8. When this grating is obliquely probed at a generalized Bragg angle, a reflected beam emerges, Doppler-shifted by 125 THz. The effect is also uni-directional, as phase-matching is strongly violated when the probe beam is reversed, so may be viewed as an ultra-high frequency Bragg-cell frequency-shifter. The wide transparency window of hydrogen allows frequency shifting of radiation from the visible to the vacuum UV, simply by tuning the incident angle. The results open up new opportunities for spatio-temporal studies of coherence wave dynamics, frequency conversion in difficult-to-access spectral regions such as the deep and vacuum UV, and quantum-state-preserving frequency conversion of single photons.
