Sökning: "grating structures"

Visar resultat 11 - 15 av 28 avhandlingar innehållade orden grating structures.

1. 11. 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

3. 12. Designs and simulations of silicon-based microphotonic devices

   Författare :Daoxin Dai; Sailing He; Siegfried Janz; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electronics; waveguide; silicon-on-insulator SOI ; arrayed waveguide grating AWG ; Elektronik; Electronics; Elektronik;

   Sammanfattning : The characteristics of a silicon-on-insulator (SOI) rib waveguide, including the bending loss of a multimode bent waveguide and the birefringence of a rib waveguide, are analyzed by using a finite-difference method (FDM). Based on a detailed analysis for a multimode bent waveguide, an appropriately designed multimode bent waveguide for reducing effectively the bending loss of the fundamental mode is realized. LÄS MER

4. 13. Scattering and propagation of electromagnetic waves in planar and curved periodic structures - applications to plane wave filters, plane wave absorbers and impedance surfaces

   Författare :Ola Forslund; KTH; []
   Nyckelord :electromagnetic scattering; periodic structure; frequency selectiove structure; frequency selective surface;

   Sammanfattning : The subject of this thesis is scattering of electromagneticwaves from planar and curved periodic structures. The problemspresented are solved in the frequency domain.Scattering from planar structures with two-dimensionalperiodic dependence of constitutive parameters is treated. LÄS MER

5. 14. Semiconductor Lasers with Gratings Defined by Electron Beam Lithography

   Författare :Torgil Kjellberg; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; lasers; field-stitching errors; single-mode stability; fiber-optic communication;

   Sammanfattning : This thesis deals with the fabrication and characterization of semiconductor lasers with gratings defined by electron-beam lithography (EBL). Both distributed-feedback (DFB) lasers for fiber-optic communication and grating-surface-emitting (GSE) lasers suitable for a number of novel applications, from free-space communication to optical processing, are treated. LÄS MER

7. 15. Studies on Domain Wall Properties andDynamics in KTiOPO4 and Rb-doped KTiOPO4

   Författare :Gustav Lindgren; Carlota Canalias; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Fysik;

   Sammanfattning : KTiOPO4 (KTP) and Rb-doped KTP (RKTP) are two of the most attractive nonlinear opticalmaterials for engineering of periodically poled domain structures, commonly used as frequencyconversiondevices for laser radiation via the quasi-phase matching (QPM) technique. Thesematerials have excellent non-linearity, wide transparency windows and high resistance to opticaldamage. LÄS MER