Sökning: "parametric processes"

Visar resultat 1 - 5 av 106 avhandlingar innehållade orden parametric processes.

1. 1. Three-wave mixing in Josephson travelling-wave parametric amplifiers

   Författare :Hampus Renberg Nilsson; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; three-wave mixing; lumped-element; four-wave mixing; SNAIL; Josephson junction; travelling-wave parametric amplifier; parametric amplifier; parametric amplification; resonant phase matching.; rf-SQUID;

   Sammanfattning : This work explores possibilities of building a wide-band, quantum-limited low-noise amplifier by means of three-wave mixing (3WM) in different kinds of Josephson travelling-wave parametric amplifiers (TWPAs). We extend the theory of the continuous three-mode model to include any number of up-converted modes in the small frequency limit where the frequency dispersion is close to linear. LÄS MER

3. 2. Optical Parametric Devices in Periodically Poled LiTaO3

   Författare :Martin Levenius; Katia Gallo; Valdas Pasiskevicius; Giuseppe Leo; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; nonlinear optics; parametric processes; frequency downconver-sion; quasi-phase matching; LiTaO3; broadband downconversion; quadratic cascading; nonlinear photonic crystals; twin-beam generation;

   Sammanfattning : Optical parametric frequency conversion based on quasi phase matching (QPM) in nonlinear optical crystals is a powerful technique for generating coherent radiation in wavelength ranges spanning from the mid-infrared (mid-IR) to the blue, displaying low thermal load and high efficiency.This thesis shows how QPM in one- (1D) or two-dimensional (2D) lattices can be employed to engineer novel devices for parametric downconversion in the IR, af-fording freedom in designing both spectral and angular properties of the parametric output. LÄS MER

4. 3. Quasi-Phasematched nonlinear processes in KTiOPO4 isomorphs

   Författare :Anna Fragemann; KTH; []
   Nyckelord :nonlinear optics; optical parametric oscillator; optical parametric amplifier; KTiOPO4; RbTiOPO4; quasi-phasematched; electric field poling;

   Sammanfattning : This thesis explores the use of nonlinear crystals from theKTiOPO4(KTP) family with the aim to extend the possibleapplications for laser sources and to gain more knowledge aboutthe material’s benefits and limits. The work focussed onoptical parametric oscillators (OPOs) and optical parametricamplifiers (OPAs), which employ second order nonlinearprocesses. LÄS MER

5. 4. Secondary Electromagnetic Radiation Generated by HF Pumping of the Ionosphere

   Författare :Lars Norin; Bo Thidé; Savely M. Grach; Bengt Gustafsson; James W. LaBelle; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; space physics; ionospheric modification experiments; plasma turbulence; stimulated electromagnetic emission; ionospheric irregularities; radio waves; parametric processes; thermal parametric instability; transient dynamics; wave-wave interactions; Physics; Fysik;

   Sammanfattning : Electromagnetic waves can be used to transmit information over long distances and are therefore often employed for communication purposes. The electromagnetic waves are reflected off material objects on their paths and interact with the medium through which they propagate. LÄS MER

7. 5. Machining Monitoring and Control : Based on Parametric Modelling

   Författare :Mats Bejhem; KTH; []
   Nyckelord :Machining Control; tool condition monitoring; in-process dynamic stability monitoring and control; optimisation of cutting conditions; MC; DSP; TCM; NATURAL SCIENCES; NATURVETENSKAP;

   Sammanfattning : The objective of this work was the development of aMachining Control prototype system for turning, whichintegrates three fundamental aspects of Machining Controltechnology: Monitoring, Control and Optimisation. MachiningControl refers to the detection and automatic handling ofdisturbances in machining processes. LÄS MER