Enhancement of bulk second-harmonic generation from silicon nitride films by material composition

We present a comprehensive tensorial characterization of second-harmonic generation from silicon nitride films with varying composition. The samples were fabricated using plasma-enhanced chemical vapor deposition, and the material composition was varied by the reactive gas mixture in the process. We found a six-fold enhancement between the lowest and highest second-order susceptibility, with the highest value of approximately 5 pm/V from the most silicon-rich sample. Moreover, the optical losses were found to be sufficiently small (below 6 dB/cm) for applications. The tensorial results show that all samples retain in-plane isotropy independent of silicon content, highlighting the controllability of the fabrication process.Comment: 4 pages, 3 figures, 2 tables; Re-submitted to Optics Letter

An integrated photoacoustic terahertz gas sensor

An on-chip gas detector that transduces absorbed terahertz light to a mechanical motion using photoacoustics is proposed. The silicon chip confines light in an optical cavity, wherein an acousto-mechanical cavity is housed. The concentration of a trace gas can be determined from the amplitude of a membrane's motion. The simulations presented predict a minimum detectable limit of 1 ppm of methanol for 1 mW of terahertz power and an integration time of 25 ms

Heterogeneously integrated InGaAsSb detectors on SOI waveguide circuits for short

Abstract: We present evanescently coupl on silicon-on-insulator waveguide circuits for short responsivity of 0.13 A/W is obtained at a wavelength of 3.5 µA at -1V

Bridging the Mid-Infrared-to-Telecom Gap with Silicon Nanophotonic Spectral Translation

Expanding far beyond traditional applications in optical interconnects at telecommunications wavelengths, the silicon nanophotonic integrated circuit platform has recently proven its merits for working with mid-infrared (mid-IR) optical signals in the 2-8 {\mu}m range. Mid-IR integrated optical systems are capable of addressing applications including industrial process and environmental monitoring, threat detection, medical diagnostics, and free-space communication. Rapid progress has led to the demonstration of various silicon components designed for the on-chip processing of mid-IR signals, including waveguides, vertical grating couplers, microcavities, and electrooptic modulators. Even so, a notable obstacle to the continued advancement of chip-scale systems is imposed by the narrow-bandgap semiconductors, such as InSb and HgCdTe, traditionally used to convert mid-IR photons to electrical currents. The cryogenic or multi-stage thermo-electric cooling required to suppress dark current noise, exponentially dependent upon the ratio Eg/kT, can limit the development of small, low-power, and low-cost integrated optical systems for the mid-IR. However, if the mid-IR optical signal could be spectrally translated to shorter wavelengths, for example within the near-infrared telecom band, photodetectors using wider bandgap semiconductors such as InGaAs or Ge could be used to eliminate prohibitive cooling requirements. Moreover, telecom band detectors typically perform with higher detectivity and faster response times when compared with their mid-IR counterparts. Here we address these challenges with a silicon-integrated approach to spectral translation, by employing efficient four-wave mixing (FWM) and large optical parametric gain in silicon nanophotonic wires

Mindfulness-Based Programs: Why, When, and How to Adapt?

This paper provides a framework for understanding why, when and how to adapt mindfulness-based programs (MBPs) to specific populations and contexts, based on research that developed and adapted multiple MBPs. In doing so, we hope to support teachers, researchers and innovators who are considering adapting an MBP to ensure that changes made are necessary, acceptable, effective, cost-effective, and implementable. Specific questions for reflection are provided such as (1) Why is an adaptation needed? (2) Does the theoretical premise underpinning mainstream MBPs extend to the population you are considering? (3) Do the benefits of the proposed adaptation outweigh the time and costs involved to all in research and implementation? (4) Is there already an evidenced-based approach to address this issue in the population or context? Fundamental knowledge that is important for the adaptation team to have includes the following: (1) essential ingredients of MBPs, (2) etiology of the target health outcome, (3) existing interventions that work for the health outcome, population, and context, (4) delivery systems and settings, and (5) culture, values, and communication patterns of the target population. A series of steps to follow for adaptations is provided, as are case examples. Adapting MBPs happens not only by researchers, but also by MBP teachers and developers, who endeavor to best serve the populations and contexts they work within. We hope that these recommendations for best practice provide a practical framework for skilfully understanding why, when, and how to adapt MBPs; and that this careful approach to adaptation maximizes MBP safety and efficacy

Examining the Evidence Base for Forensic Case Formulation: An Integrative Review of Recent Research

In the past decade, forensic case formulation (FCF) has become a key activity in many forensic services. However, the evidence base for FCF remains limited. This integrative review aimed to identify and evaluate all FCF research conducted since the lack of understanding within this field was highlighted by several academics in 2011. A rigorous literature search led to the identification of 14 studies fitting the inclusion criteria. Studies were critically evaluated and synthesised to create a summary of the recent research, to identify remaining gaps in our understanding, and to create an agenda for future research