RESUMO
Magnetic-free nonreciprocal optical devices have attracted great attention in recent years. Here, we investigated the magnetic-free polarization rotation of light in an atom vapor cell. Two mechanisms of magnetic-free nonreciprocity have been realized in ensembles of hot atoms, including electromagnetically induced transparency and optically-induced magnetization. For a linearly polarized input probe light, a rotation angle up to 86.4° has been realized with external control and pump laser powers of 10â mW and is mainly attributed to the optically-induced magnetization effect. Our demonstration offers a new approach to realize nonreciprocal devices, which can be applied to solid-state atom ensembles and may be useful in photonic integrated circuits.
RESUMO
OBJECTIVE: To systematically study the chemical constituents in the roots of Gentiana dahurica. METHODS: Various column chromatographic techniques were used for isolation and purification. The structures were elucidated on the basis of spectral data (UV, IR, MS, NMR) and identified by comparing with the authentic substance. RESULTS: Seven compounds were isolated and identified as: roburic acid (1), oleanolic acid (2), beta-sitosterol (3), daucosterol (4), gentiopicroside(5), swertiamarine (6), sweroside (7). CONCLUSION: Compounds 1, 2 and 4 are isolated from this plant for the first time.
