We demonstrate single-mode uniform and parabolically tapered three-dimensional waveguides fabricated via direct-write lithography in diffusion-based photopolymers. Modulation of the writing power is shown to compensate Beer-Lambert absorption in the single-photon initiator and to provide precise control of modal tapers. A laminated sample preparation is introduced to enable full 3D characterization of these modal tapers without the need for sample polishing which is difficult for this class of polymer. The accuracy and repeatability of this modal characterization is shown to allow precise measurement of propagation loss from single samples. These testing procedures are used to demonstrate single-mode waveguides with 0.147 dB/cm excess propagation loss and symmetrical tapers up to 1:2.5 using 1.5 microwatts of continuous write power.

No abstract

We demonstrate single mode three-dimensional optics fabricated via direct-write lithography in diffusive photopolymers, including uniform waveguides, symmetrical waveguide tapers, 90 0 OCIS codes: sharp waveguide bends and waveguides through thin hybrid subcomponents. (130.3120) Integrated optics devices; (230.7370) Waveguides; (140.3450) Laser-induced chemistry.

OVERVIEW:In its report to the Chief of Engineers, the U.S. Army Corps of Engineers (USACE) Environmental Advisory Board (EAB) recommended that (USACE, EAB 2006 Conceptual models are descriptions of the general functional relationships among essential components of an ecosystem. They tell the story of "how the system works" and, in the case of ecosystem restoration, how restoration actions aim to alter those processes or attributes for the betterment of the system. As such, conceptual models can provide the Ecosystem Restoration Team with:• a synthesis of the current understanding of how a system works • help in understanding and diagnosing the underlying problem • a basis for isolating cause and effect and simplifying complex systems • a common framework or "mental picture" from which to develop alternatives • a tool for making qualitative predictions of ecosystem response • a way to flag potential thresholds, from which system responses may accelerate or follow potentially unexpected or divergent paths • a means by which to outline further restoration, R&D, and computational efforts • a supplement to numerical models for assessing project benefits and impacts • a means of identifying appropriate monitoring indicators and metrics, and • a basis for implementing adaptive management strategies Most professionals rely heavily upon conceptual models, but few explicitly formulate and express the models such that they provide broad utility for ecosystem restoration. Model building consists of determining system parts, choosing the relationships that link these parts, specifying the mechanisms by which the parts interact, identifying missing information, and exploring the model behavior (Heemskerk et al. 2003). The model building process can be as enlightening as the model itself, because it reveals what is known and what is unknown about the connections and causalities in the systems under study.