Bandwidth Limitation in Slow Light Schemes

Yanyan Ma, Rong Wu, Longfei Li

Jesper Mørk

De-Kui Qing, Zhijie Deng, C. H. Raymond Ooi +2 more

A critical limitation of slow light schemes is the limited time-bandwidth product. Recently we showed that this limitation can be overcome by making use of inhomogeneities. Here we analyze the effects of crosstalk noise that can be induced by these inhomogeneities in certain situations, and how to minimize such noise. The proof of principle experiment was done using three-wave mixing in a photorefractive crystal Ce:BaTiO3 where Bragg selection is used to provide the inhomogeneity.

Fu‐Long Shi, Xiao‐Dong Chen, Wen-Jie Chen +1 more

Delay-bandwidth product (DBP) is a key metric in slow light waveguides, requiring a balance between a large group index and broad bandwidth—two parameters that often involve a trade-off. Here, we propose and demonstrate a slow light waveguide with large DBP using a pseudospin-polarized transverse electromagnetic mode. This waveguide features a folded edge configuration that supports a 200% relative bandwidth from quasistatic limit (zero frequency) and an arbitrarily large group index. Owing to the pseudospin-polarized design, the dense folding would not introduce backscattering and the associated group velocity dispersion (GVD). The resulting gapless linear dispersion and pulse transmission behavior in folded edge waveguide are observed in microwave experiments. Our scheme provides a way to overcome the trade-off between group index and working bandwidth in slow light waveguide, which has potential applications in broadband optical buffering, light-matter interaction enhancement, terahertz radiation source and time domain processing. Delay-bandwidth product (DBP), which require a large group index and a wide bandwidth, is an important indicator in slow light waveguides. This work relaxes the trade-off between group velocity and working bandwidth in 200% relative bandwidth, and realizes a pseudospin-polarized slow-light waveguide with large DBP and low group velocity dispersion.

Jacob B. Khurgin

I consider the physical basics of slow light propagation in atomic media, photonic structures, and optical fibers. I show similarities and differences between all of the above media and develop set of criteria that are then used to compare different media. Special attention is given to dispersion of group velocity and loss, which are shown to limit the bandwidth and delay capacity of all the slow light schemes.