Robust optical delay lines via topological protection

Phenomena associated with topological properties of physical systems are naturally robust against perturbations. This robustness is exemplified by quantized conductance and edge state transport in the quantum Hall and quantum spin Hall effects. Here we show how exploiting topological properties of optical systems can be used to implement robust photonic devices. We demonstrate how quantum spin Hall Hamiltonians can be created with linear optical elements using a network of coupled resonator optical waveguides (CROW) in two dimensions. We find that key features of quantum Hall systems, including the characteristic Hofstadter butterfly and robust edge state transport, can be obtained in such systems. As a specific application, we show that the topological protection can be used to dramatically improve the performance of optical delay lines and to overcome limitations related to disorder in photonic technologies.Comment: 9 pages, 5 figures + 12 pages of supplementary informatio

Silicon optical modulators

Optical technology is poised to revolutionize short-reach interconnects. The leading candidate technology is silicon photonics, and the workhorse of such an interconnect is the optical modulator. Modulators have been improved dramatically in recent years, with a notable increase in bandwidth from the megahertz to the multigigahertz regime in just over half a decade. However, the demands of optical interconnects are significant, and many questions remain unanswered as to whether silicon can meet the required performance metrics. Minimizing metrics such as the device footprint and energy requirement per bit, while also maximizing bandwidth and modulation depth, is non-trivial. All of this must be achieved within an acceptable thermal tolerance and optical spectral width using CMOS-compatible fabrication processes. This Review discusses the techniques that have been (and will continue to be) used to implement silicon optical modulators, as well as providing an outlook for these devices and the candidate solutions of the future

Radiolarian and agglutinated foraminiferal biostratigraphy of the Paleogene deep-water deposits on the northern margin of the Carpathian Tethys (Skole Unit)

Radiolarian and agglutinated foraminiferal fauna within upper deposits of the Skole Unit of the Polish Flysch Outer Carpathians occur in the Variegated Shale and Hieroglyphic formations of Paleocene and Eocene age. About 70 radiolarian and 50 foraminiferal species have been identified and their stratigraphic distribution determined using both regional and local biozonations. Five radiolarian zones: the Bekoma bidartensis Interval Zone, the Buryella clinata Interval Zone, the Phormocyrtis striata striata Interval Zone, the Theocotyle cryptocephala Interval Zone and the Dictyoprora mongolfieri Interval Zone in the lower Eocene and in the lower part of the middle Eocene have been distinguished. In the upper part of the middle Eocene and in the uper Eocene the abundance of radiolarians decreases and their age assignment has not been possible. Five foraminiferal zones have been distinguished and correlated with radiolarian zones based on co-occurrence of both Protista groups in the deposits investigated. These are: the Rzehakina fissistomata Zone, the Saccamminoides carpathicus Zone, the Reticulophragmium amplectens Zone, the Ammodiscus latus Zone and the Cyclammina rotundidorsata Zone covering the time span from upper Paleocene to upper Eocene