Expanded-beam backside coupling interface for alignment-tolerant packaging of silicon photonics

We demonstrate an alignment-tolerant backside coupling interface in the O-band for silicon photonics by generating an optimized through-substrate (downward) directionality beam from a TE-mode grating coupler and hybrid integrating the chip with backside silicon microlenses to achieve expanded beam collimation. The key advantage of using such an expanded beam interface is an increased coupling tolerance to lateral and longitudinal misalignment. A 34 mu m beam diameter was achieved over a combined substrate thickness of 630 mu m which was then coupled to a thermally expanded core single-mode fiber to investigate the tolerances. A 1-dB fiber-to-microlens lateral alignment tolerance of 14 mu m and an angular alignment tolerance of 1 degrees was measured at a wavelength of 1310 nm. In addition, a large +/- 2.5 mu m 1-dB backside alignment accuracy was measured for the placement of microlens with respect to the grating. The radius of curvature of Si microlens to achieve a collimated beam was 480 mu m, and a 1-dB longitudinal alignment tolerance of 700 mu m was measured for coupling to a single-mode expanded core fiber. The relaxation in alignment tolerances make the demonstrated coupling interface suitable for chip-to-package or chip-to-board couplin

Tuning a racetrack ring resonator by an integrated dielectric MEMS cantilever

The principle, fabrication and characterization of a dielectric MEMS cantilever located a few 100 nm above a racetrack ring resonator are presented. After fabrication of the resonators on silicon-on-insulator (SOI) wafers in a foundry process, the cantilevers were integrated by surface micromachining techniques. Off-state deflections of the cantilevers have been optimized to appropriately position them near the evanescent field of the resonator. Using electrostatic actuation, moving the cantilevers into this evanescent field, the propagation properties of the ring waveguide are modulated. We demonstrate 122 pm tuning of the resonance wavelength of the optical ring resonator (in the optical C-band) without change of the optical quality factor, on application of 9 V to a 40 µm long cantilever. This compact integrated device can be used for tuning/switching a specific wavelength, with very little energy for operation and negligible cross talk with surrounding device

GravityCam: higher resolution visible wide-field imaging

The limits to the angular resolution has, during the latest 70 years, been obtainable from the ground only through extremely expensive adaptive optics facilities at large telescopes, and covering extremely small spatial areas per exposure. Atmospheric turbulence therefore limits image quality to typically 1 arcsec in practice. We have developed a new concept of ground-based imaging instrument called GravityCam capable of delivering significantly sharper images from the ground than is normally possible without adaptive optics. The acquisition of visible images at high speed without significant noise penalty has been made possible by advances in optical and near IR imaging technologies. Images recorded at high speed can be aligned before combination and can yield a 3-5 fold improvement in image resolution, or be used separately for high-cadence photometry. Very wide survey fields are possible with widefield telescope optics. GravityCam is proposed to be installed at the 3.6m New Technology Telescope (NTT) at the ESO La Silla Observatory in Chile, where it will greatly accelerate the rate of detection of Earth sized planets by gravitational microlensing. GravityCam will also improve substantially the quality of weak shear studies of dark matter distribution in distant clusters of galaxies and provide a vast dataset for asteroseismology studies. In addition, GravityCam promises to generate a unique data set that will help us understand of the population of the Kuiper belt and possibly the Oort cloud

Lynx X-Ray Observatory: An Overview

Lynx, one of the four strategic mission concepts under study for the 2020 Astrophysics Decadal Survey, provides leaps in capability over previous and planned x-ray missions and provides synergistic observations in the 2030s to a multitude of space- and ground-based observatories across all wavelengths. Lynx provides orders of magnitude improvement in sensitivity, on-axis subarcsecond imaging with arcsecond angular resolution over a large field of view, and high-resolution spectroscopy for point-like and extended sources in the 0.2- to 10-keV range. The Lynx architecture enables a broad range of unique and compelling science to be carried out mainly through a General Observer Program. This program is envisioned to include detecting the very first seed black holes, revealing the high-energy drivers of galaxy formation and evolution, and characterizing the mechanisms that govern stellar evolution and stellar ecosystems. The Lynx optics and science instruments are carefully designed to optimize the science capability and, when combined, form an exciting architecture that utilizes relatively mature technologies for a cost that is compatible with the projected NASA Astrophysics budget

The Silicon Meta-shell X-ray Mirror Technology Development Roadmap for the Lynx Mission

This document presents a roadmap for advancing the silicon meta-shell optics (SMO). It describes an overall strategy and key technical elements to be developed to meet the four-fold Lynx requirements: (1) angular resolution, (2) effective area, (3) mass, and (4) production schedule and cost. It also describes the building and testing of an engineering unit whose successful completion will retire all risks, technical, logistical, schedule, and cost, associated with building and delivering a mirror assembly for the Lynx mission. All of this work, designed to advance this technology to TRL 6, will be completed by Preliminary Design Review (PDR) to ensure that the flight mirror assembly production process will be but a repetition of a set of well-defined and mature steps, leading to on-time and on-budget delivery of a mirror assembly for the Lynx mission