Sökning: "Terahertz"

Visar resultat 1 - 5 av 26 uppsatser innehållade ordet Terahertz.

1. 1. Digitally Controlled Oscillator Topologies for mm-Wave Pulsed Coherent Radar

   Master-uppsats, Lunds universitet/Institutionen för elektro- och informationsteknik

   Författare :Klas Junskog; [2023]
   Nyckelord :oscillators; mm-wave; radar; Technology and Engineering;

   Sammanfattning : The advancement of future generations of wireless communication and radar sensing warrants the need for mm-wave digitally controlled oscillators (DCOs) with high-frequency trade-offs in consideration. The purpose of this project is to investigate DCO topologies inspired from scientific literature. LÄS MER

3. 2. Towards a setup for narrowband terahertz generation through difference-frequency mixing of chirped ultrashort pulses

   Master-uppsats, Lunds universitet/Atomfysik; Lunds universitet/Fysiska institutionen

   Författare :Isa Clementsson; [2023]
   Nyckelord :Physics and Astronomy;

   Sammanfattning : Terahertz radiation is a useful tool for inducing lower-energy excitations in matter, where it can be used to cause structural changes through direct interaction with the crystal lattice. Sub-picosecond optical pulses can be used to generate intense broadband terahertz pulses through optical rectification in nonlinear crystals, reaching peak electric fields of several MV/m and conversion efficiencies as high as a few percent. LÄS MER

4. 3. Simulation of Quantum Cascade Lasers

   Kandidat-uppsats, Lunds universitet/Fysiska institutionen; Lunds universitet/Matematisk fysik

   Författare :Zakaria Mohamed; [2023]
   Nyckelord :Quantum Cascade Lasers; Simulations; Numerical Methods; Computational Models; Heterostructures; Physics and Astronomy;

   Sammanfattning : This thesis aimed to contribute to the improvement of Quantum Cascade Lasers (QCLs) by focusing on the effective determination of quantum levels in these devices. The current method relies on an outdated Fortran code, which poses challenges when integrating into optimization schemes. LÄS MER

5. 4. Simulation, Design, and Implementation of a Narrow Linewidth Ytterbium Fiber MOPA System at 1087 nm

   Master-uppsats, KTH/Tillämpad fysik

   Författare :Berkay Efilti; [2023]
   Nyckelord :Applied Physics; Laser Physics; Fiber Lasers; Fiber Amplifiers;

   Sammanfattning : This thesis focuses on simulating, designing, and characterizing a narrow-linewidth continuous-wave (CW) Ytterbium (Yb) master oscillator fiber amplifier (MOFA) system. The primary goal was to achieve a watt-level output at 1087 nm with a narrow 1 GHz linewidth, making the MOFA well-suited for serving as a pump source in Terahertz (THz) generation experiments. LÄS MER

7. 5. Time-resolved x-ray diffraction study of longitudinal optical phonons in zincblende semiconductors

   Master-uppsats, Lunds universitet/Atomfysik; Lunds universitet/Fysiska institutionen

   Författare :Lassi Linnala; [2022]
   Nyckelord :femtosecond THz radiation; ultrafast x-ray diffraction; pump-probe; longitudinal optical phonons; zincblende semiconductors; anharmonic decay; density functional perturbation theory; Physics and Astronomy;

   Sammanfattning : Anharmonic decay of longitudinal optical (LO) phonons in zincblende semiconductors is not at present well characterized due to the polar and many-body nature of the problem. Femtosecond THz radiation offers a novel route to this study, as the interaction of this radiation is directly with the phonon lattice and these THz excited phonons do not have enough energy to excite electrons over the band gap. LÄS MER