Optical frequency combs have the potential to revolutionize terabit communications1. Generation of Kerr combs in nonlinear microresonators2 represents a particularly promising option3 enabling line spacings of tens of GHz. However, such combs may exhibit strong phase noise4-6, which has made high-speed data transmission impossible up to now. Here we demonstrate that systematic adjustment of pump conditions for low phase noise4,7-9 enables coherent data transmission with advanced modulation formats that pose stringent requirements on the spectral purity of the comb. In a first experiment, we encode a data stream of 392 Gbit/s on a Kerr comb using quadrature phase shift keying (QPSK) and 16-state quadrature amplitude modulation (16QAM). A second experiment demonstrates feedback-stabilization of the comb and transmission of a 1.44 Tbit/s data stream over up to 300 km. The results show that Kerr combs meet the highly demanding requirements of coherent communications and thus offer an attractive solution towards chip-scale terabit/s transceivers.

Photocatalytic hydrogen evolution via water splitting is an attractive scientific and technological goal to address the increasing global demand for clean energy and to reduce the climate change impact of CO2 emission. Although tremendous efforts have been made, hydrogen production by a robust and highly efficient system driven by visible light still remains a significant challenge. Herein we report that nickel phosphide, as a cocatalyst to form a well-designed integrated photocatalyst with one-dimensional semiconductor nanorods, highly improves the efficiency and durability for photogeneration of hydrogen in water. The highest rate for hydrogen production reached ~1,200 μmol·h -1 •mg -1 based on the photocatalyst.The turnover number (TON) reached ~3,270,000 in 90 hours with a turnover frequency (TOF) of 36,400 for Ni2P, and the apparent quantum yield was ~41% at 450 nm. The photoinduced charge transfer process was further confirmed by steady-state photoluminescence spectra and time-resolved photoluminescence spectra. Such extraordinary performance of a noble-metal-free artificial photosynthetic hydrogen production system has, to our knowledge, not been reported to date.

The present study shows that p-type copper phosphide (Cu3P) can be an efficient promoter to improve photocatalytic H2 production from water when loaded on n-type cadmium sulphide nanorods.

We report that a photocatalyst made of amorphous cobalt phosphide (CoPx) integrated with CdS NRs for H2 production under visible light. The CoPx/CdS NRs gave an apparent quantum yield at ∼35% (λ = 450 nm).

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A free-space optical delay interferometer (DI) featuring a continuously tunable time delay, polarization insensitive operation with high extinction ratios and accurate phase and time delay monitoring scheme is reported. The polarization dependence is actively mitigated by adjusting a birefringent liquid-crystal device. The DI has been tested for reception of D(m)PSK signals. ©2011 Optical Society of America

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