Sökning: "Spectral matching"

Visar resultat 16 - 20 av 46 avhandlingar innehållade orden Spectral matching.

  1. 16. Thick Frequency Selective Structures

    Författare :Björn Widenberg; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; acoustics; Elektromagnetism; optik; akustik; optics; Electromagnetism; Energy Saving Window; Radome; Finite Elemente Method; Frequency Selective Structure; Mode Matching Technique;

    Sammanfattning : This thesis presents a new method that can handle a general thick Frequency Selective Structure (FSS), that consists of an arbitrary number of aperture layers and dielectric layers. The method is based on the Mode Matching Technique (MMT) and the finite element method (FEM). The thesis consists of a General Introduction and five scientific papers. LÄS MER

  3. 17. Advanced nano- and microdomain engineering of Rb-doped KTiOPO4 for nonlinear optical applications

    Författare :Charlotte Liljestrand; Carlota Canalias; Sunao Kurimura; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; KTiOPO4; nonlinear optics; MOPO; quasi-phase matching; SHG; ferroelectrics; domain structuring; periodic poling; Fysik; Physics;

    Sammanfattning : Fine-pitch ferroelectric domain gratings are extensively used for generation of light in the visible and near-infrared spectral regions through quasi-phase matched (QPM) frequency conversion. Sub-μm QPM devices enables demonstration of nonlinear optics with counterpropagating waves, a field of nonlinear optics which remains sparsely explored due to the difficulty of fabricatinghigh quality gratings. LÄS MER

  4. 18. Nonlinear optics in KTiOPO4 for spectral management of ultra-short pulses in the near- and mid-IR

    Författare :Anne-Lise Viotti; Valdas Pasiskevicius; Fredrik Laurell; Paulina Kuo; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Nonlinear optics; Ferroelectrics; Fysik; Physics;

    Sammanfattning : This thesis explores the possibilities of controlling nonlinear optical interactions in ferroelectric materials for bandwidth tailoring of ultrashort pulses in the pico- and femto-second range. The control is achieved through quasi-phase matching, which is based on alternating the material’s spontaneous polarization into different domains. LÄS MER

  5. 19. Short Pulses in Engineered Nonlinear Media

    Författare :Stefan Holmgren; Fredrik Laurell; Derryck Reid; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; nonlinear optics; KTiOPO4; frequency conversion; mode-locked lasers; ultra-fast lasers; visible lasers; short pulses; ultrafast nonlinear optics; diagnostic applications of nonlinear optics; nonlinear optical materials; Physics; Fysik;

    Sammanfattning : Short optical pulses and engineered nonlinear media is a powerful combination. Mode locked pulses exhibit high peak powers and short pulse duration and the engineered ferro-electric KTiOPO4 facilitates several different nonlinear processes. LÄS MER

  7. 20. Optical detection of joint position in zero gap laser beam welding

    Författare :Morgan Nilsen; Anna-Karin Christiansson; Fredrik Sikström; Högskolan Väst; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Laser beam welding; Optical sensors; Joint tracking; Production Technology; Produktionsteknik; Manufacturing and materials engineering; Produktions- och materialteknik;

    Sammanfattning : This thesis presents an experimental study on how to track zero gaps between metal sheets to be joined by laser beam butt welding. Automated laser beam welding is gaining interest due to its ability to produce narrow and deep welds giving limited heat input and therefore less distortions compared to other processes, such as arc-welding. LÄS MER