Sökning: "high-contrast grating"

Hittade 5 avhandlingar innehållade orden high-contrast grating.

  1. 1. VCSELs for High-Speed, Long-Reach, and Wavelength-Multiplexed Optical Interconnects

    Författare :Erik Haglund; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; mode filter; high-contrast grating; oxide aperture; high-speed modulation; wavelength control; spectral width; vertical-cavity surface-emitting laser; optical interconnect; quasi-single-mode;

    Sammanfattning : The vertical-cavity surface-emitting laser (VCSEL) is the standard light source in short-reach fiber-optic links in datacenters and supercomputers. These systems use an enormous number of links, making cost and energy efficiency pressing issues. LÄS MER

  3. 2. Optical Guiding and Feedback in Gallium Nitride Based Vertical Cavity Surface Emitting Lasers

    Författare :Seyed Ehsan Hashemi; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; antiguiding; vertical-cavity surface-emitting laser; gallium nitride laser; TiO2 high contrast grating;

    Sammanfattning : The gallium-nitride (GaN) semiconductor material has been the core of the revolutionary breakthroughs during the last two decades in the lighting industry, by enabling manufacturing of efficient blue light emitting diodes (LEDs), for which the 2014 Nobel prize in physics was awarded. The GaN technology has further led to violet edge-emitting lasers (EELs), enabling the Blu-ray disk technology, and also to the commercialization of directly green emitting EELs. LÄS MER

  4. 3. Photonic devices with MQW active material and waveguide gratings : modelling and characterisation

    Författare :Nadeem Akram; Lars Thylén; Hartmut Hillmer; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Method of Lines; Grating; ARROW Waveguide; Semiconductor laser; quantum well; Photonics; Fotonik;

    Sammanfattning : The research work presented in this thesis deals with modelling, design and characterisation of passive and active optical waveguide devices. The rst part of the thesis is related to algorithm development and numerical modelling of planar optical waveguides and gratings using the Method of Lines (MoL). LÄS MER

  5. 4. Improving Peripheral Vision Through Optical Correction and Stimulus Motion

    Författare :Peter Lewis; Peter Unsbo; Linda Lundström; Jörgen Gustafsson; Michael Crossland; Linnéuniversitetet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; absolute central scotoma; central visual field loss; eccentric viewing; preferred retinal locus; open-view aberrometer; off-axis refractive errors; eccentric correction; dynamic visual acuity; spatial contrast sensitivity; temporal contrast sensitivity; spatio-temporal contrast sensitivity; Optometry; Optometri; Biomedical Sciences; Biomedicinsk vetenskap;

    Sammanfattning : The loss of central vision subsequent to macular disease is often extremely debilitating. People with central field loss (CFL) must use other peripheral areas of the retina in order to see; areas with inferior resolution capacity, which are also affected by off-axis optical errors. LÄS MER

  7. 5. Spatial Vision in Bees : Behavioural investigation of spatial resolution and contrast sensitivity

    Författare :Aravin Chakravarthi; Funktionell zoologi; []
    Nyckelord :Insect vision; Honeybees; Bumblebees; Spatial resolution; Contrast sensitivity; Motion detection; Object discrimination;

    Sammanfattning : Bees use multiple sensory modalities to perform day-to-day tasks. Light allows them to perceive objects and the general features of their surroundings, enabling them to find food and to navigate safely across the landscape. LÄS MER