A Semiconductor Under Insulator Technology in Indium Phosphide

This Letter introduces a Semiconductor-Under-Insulator (SUI) technology in InP for designing strip waveguides that interface InP photonic crystal membrane structures. Strip waveguides in InP-SUI are supported under an atomic layer deposited insulator layer in contrast to strip waveguides in silicon supported on insulator. We show a substantial improvement in optical transmission when using InP-SUI strip waveguides interfaced with localized photonic crystal membrane structures when compared with extended photonic crystal waveguide membranes. Furthermore, SUI makes available various fiber-coupling techniques used in SOI, such as sub-micron coupling, for planar membrane III-V systems

A Communication Model for Large Intelligent Surfaces

The purpose of this paper is to introduce a communication model for Large Intelligent Surfaces (LIS). A LIS is modelled as a collection of tiny closely spaced antenna elements. Due to the proximity of the elements, mutual coupling arises. An optimal transmitter design depends on the mutual coupling matrix. For single user communication, the optimal transmitter uses the inverse of the mutual coupling matrix in a filter matched to the channel vector. We give the expression of the mutual coupling for two types of planar arrays. The conditioning number of the mutual coupling matrix is unbounded as the antenna element density increases, so only the dominant values can be inverted within reasonable computation. The directivity is partial but still significant compared to the conventional gain. When the spacing between elements becomes small (smaller than half a wavelength), the directivity surpasses the conventional directivity equal to the number of antennas, as well as the gain obtained when modelling the surface as continuous. The gain is theoretically unbounded as the element density increases for a constant aperture.Comment: 6 pages, 7 figures; typos correcte

The therapeutic effects of the physician-older patient relationship: Effective communication with vulnerable older patients

There is growing evidence that the outcomes of health care for seniors are dependent not only upon patients’ physical health status and the administration of care for their biomedical needs, but also upon care for patients’ psychosocial needs and attention to their social, economic, cultural, and psychological vulnerabilities. Even when older patients have appropriate access to medical services, they also need effective and empathic communication as an essential part of their treatment. Older patients who are socially isolated, emotionally vulnerable, and economically disadvantaged are particularly in need of the social, emotional, and practical support that sensitive provider-patient communication can provide. In this review paper, we examine the complexities of communication between physicians and their older patients, and consider some of the particular challenges that manifest in providers’ interactions with their older patients, particularly those who are socially isolated, suffering from depression, or of minority status or low income. This review offers guidelines for improved physician-older patient communication in medical practice, and examines interventions to coordinate care for older patients on multiple dimensions of a biopsychosocial model of health care

All-optical conditional logic with a nonlinear photonic crystal nanocavity

We demonstrate tunable frequency-converted light mediated by a chi-(2) nonlinear photonic crystal nanocavity. The wavelength-scale InP-based cavity supports two closely-spaced localized modes near 1550 nm which are resonantly excited by a 130 fs laser pulse. The cavity is simultaneously irradiated with a non-resonant probe beam, giving rise to rich second-order scattering spectra reflecting nonlinear mixing of the different resonant and non-resonant components. In particular, we highlight the radiation at the sum frequencies of the probe beam and the respective cavity modes. This would be a useful, minimally-invasive monitor of the joint occupancy state of multiple cavities in an integrated optical circuit.Comment: 4 pages, 4 figure

Second-Order Nonlinear Mixing of Two Modes in a Planar Photonic Crystal Microcavity

Polarization-resolved second-harmonic spectra are obtained from the resonant modes of a two-dimensional planar photonic crystal microcavity patterned in a free-standing InP slab. The photonic crystal microcavity is comprised of a single missing-hole defect in a hexagonal photonic crystal host formed with elliptically-shaped holes. The cavity supports two orthogonally-polarized resonant modes split by 60 wavenumbers. Sum-frequency data are reported from the nonlinear interaction of the two coherently excited modes, and the polarization dependence is explained in terms of the nonlinear susceptibility tensor of the host InP.Comment: 7 pages, 8 Postscript figures, to be presented at Photonics West Jan. 2