40 GBd 16QAM signaling at 160 Gb/s in a silicon-organic hybrid modulator

We demonstrate for the first time generation of 16-state quadrature amplitude modulation (16QAM) signals at a symbol rate of 40 GBd using silicon-based modulators. Our devices exploit silicon-organic hybrid (SOH) integration, which combines silicon-on-insulator slot waveguides with electro-optic cladding materials to realize highly efficient phase shifters. The devices enable 16QAM signaling and quadrature phase shift keying (QPSK) at symbol rates of 40 GBd and 45 GBd, respectively, leading to line rates of up to 160 Gbit/s on a single wavelength and in a single polarization. This is the highest value demonstrated by a silicon-based device up to now. The energy consumption for 16QAM signaling amounts to less than 120 fJ/bit – one order of magnitude below that of conventional silicon photonic 16QAM modulators

Unlocking the Climate Record Stored within Mars’ Polar Layered Deposits

In the icy beds of its polar layered deposits (PLD), Mars likely possesses a record of its recent climate history, analogous to terrestrial ice sheets that contain records of Earth's past climate. Both northern and southern PLDs store information on the climatic and atmospheric state during the deposition of each layer (WPs: Becerra et al.; Smith et al). Reading the climate record stored in these layers requires detailed measurements of layer composition, thickness, isotope variability, and near-surface atmospheric measurements. We identify four fundamental questions that must be answered in order to interpret this climate record and decipher the recent climatic history of Mars: 1. Fluxes: What are the present and past fluxes of volatiles, dust, and other materials into and out of the polar regions? 2. Forcings: How do orbital/axial forcing and exchange with other reservoirs affect those fluxes? 3. Layer Processes: What chemical and physical processes form and modify layers? 4. Record: What is the timespan, completeness, and temporal resolution of the climate history recorded in the PLD? In a peer reviewed report (1), we detailed a sequence of missions, instruments, and architecture needed to answer these questions. Here, we present the science drivers and a mission concept for a polar lander that would enable a future reading of the past few million years of the Martian climate record. The mission addresses as-yet-unachieved science goals of the current Decadal Survey and of MEPAG for obtaining a record of Mars climate and has parallel goals to the NEXSAG and ICE-SAG reports

A Theoretical and Synthetic Investigation of New Donors for Organic Electro-Optic Chromophores: Understanding the Effects of Structure and Substituents on Donor Strength

Thesis (Ph.D.)--University of Washington, 2016-08Understanding of the intricate connection between shape, structure and property has al- lowed many challenges facing the adoption of organic chromophores for electro-optic (EO) applications to be overcome. Still, there is much to be learned about designing donors that localize electron density in the ground state, but not in the electronically polarized state to allow for enhanced charge transfer, and thus, large first-order molecular hyperpolarizability (β). To address this, density functional theory has been used to evaluate a large number of potential donors based on alkyl, aryl, saturated and unsaturated heterocycles. These were coupled to the tricyanopyrroline (TCP) acceptor by a simple vinylic bridge to identify new high β, high number density materials. Saturated heterocylces were found to off the largest improvements over traditional dialkyl donors, with the predicted systems rival- ing much longer polyene-based chromophores with a trifluoromethyl, phenyl-tricyanofuran (CF3PhTCF). Other potential candidates where based on diaryl amines donors which are a natural progression from previous heteroaryl chromophores. These systems were typified by a greater degree of localized electron density – by as much as 20% – at the donor and were found to exhibit characteristics that might described as a double-donor. Several novel chromophores based on these new donors were synthesized to verify the theoretical results and evaluate their potential for use in EO devices