This study demonstrates etch profile engineering of InP, In1−xGaxAs1−yPy, and In0.53Ga0.47As heterostructures results from adding H2 to standard Cl2/Ar inductively coupled plasma-reactive ion etching chemistries. Etch rate curves of bulk InP, In1−xGaxAs1−yPy, and In0.53Ga0.47As show a general parabolic trend as a function of the H2 component of the Cl2/Ar/H2 ratio. Three distinct etching profiles of InP/InGaAsP layers were realized by varying the Cl2/Ar/H2 ratio. Highly anisotropic profiles result for Cl2/Ar/H2 ratios between 2/3/1 and 2/3/2. Waveguiding structures fabricated using this technology are presented with a loss as low as 2 dB/cm. An InP racetrack resonator with a quality factor (Q)>8000 is also presented.

The Direct Fusion Drive (DFD), a compact, anuetronic fusion engine, will enable more challenging exploration missions in the solar system. The engine proposed here uses a deuterium-helium-3 reaction to produce fusion energy by employing a novel field-reversed configuration (FRC) for magnetic confinement. The FRC has a simple linear solenoid coil geometry yet generates higher plasma pressure, hence higher fusion power density, for a given magnetic field strength than other magnetic-confinement plasma devices. Waste heat generated from the plasma's Bremsstrahlung and synchrotron radiation is recycled to maintain the fusion temperature. The charged reaction products, augmented by additional propellant, are exhausted through a magnetic nozzle. A 1 MW DFD is presented in the context of a mission to deploy the James Webb Space Telescope (6200 kg) from GPS orbit to a Sun-Earth L2 halo orbit in 37 days using just 353 kg of propellant and about half a kilogram of 3 He. The engine is designed to produce 40 N of thrust with an exhaust velocity of 56.5 km/s and has a specific power of 0.18 kW/kg.

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We demonstrate a photonic integrated circuit using a novel monolithic integration platform combining InGaAsP gain elements and index matched amorphous silicon waveguide devices. The AWG based multi-frequency laser emits eight 100-GHz-spaced wavelengths near 1550 nm.OCIS codes: (250.5300) Photonic integrated circuits 1. Introduction Integration of photonic circuits is required to satisfy growing bandwidth demands in cost sensitive communication networks at affordable cost. Monolithic photonic circuits containing both active and passive components have been demonstrated using various integration techniques. Typically, the materials used for active as well as passive components in monolithic systems are InP and lattice matched epitaxially grown semiconductor compounds InGaAsP, GaInAlAs [1][2][3][4][5]. Most integrated devices require very low reflections and low loss at active-passive transitions. This makes materials that are popular for passive optical components such as SiO2/SiN/SiON and polymers less attractive for monolithic integration due to refractive indices much lower than those of the III/V compounds. Amorphous silicon alloys, transparent at telecommunication wavelengths (1310, 1550 nm), can be made with refractive indices matching those of III/V semiconductors but do not require lattice matched epitaxy. Optical waveguides made of amorphous silicon alloys deposited on silicon substrates have been explored in [6][7][8]. Low temperature PECVD deposition of amorphous silicon alloys makes this material system compatible with III/V components and substrates. In this paper we demonstrate the first monolithically integrated device combining amorphous silicon and III/V components. We have designed and fabricated a multi-frequency laser, which consists of InGaAsP/InP gain elements, and amorphous silicon waveguides, an amorphous silicon arrayed waveguide grating (AWG) and an amorphous silicon multimode interference (MMI) splitter monolithically integrated on an InP substrate.

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