Search for dissertations about: "spectral lineshape"

Found 5 swedish dissertations containing the words spectral lineshape.

  2. 1. Lineshape in Quantum Cascade Lasers - Temperature, Screening and Broadening

    Author : Rikard Nelander; Matematisk fysik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Quantum Cascade Lasers; quantum wells; spectral lineshape; Non-Equilibrium Green s Functions; screening; temperature dependence;

    Abstract : This dissertation deals with the optical properties of Quantum Cascade Lasers (QCLs). Studies are performed using transport calculations employing the theory of Non-Equilibrium Green's Functions, and screening is studied within the Random Phase Approximation. Focus is put on the temperature dependent effects in THz QCLs. READ MORE

  4. 2. Dicke narrowing and speed-dependent effects in dispersion signals : Influence on assessment of concentration and spectral parameters by noise-immune cavity-enhanced optical heterodyne molecular spectrometry

    Author : Junyang Wang; Ove Axner; Livio Gianfrani; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Dicke narrowing; Speed-dependent effects; Dispersion signals; Noise-immune cavity-enhanced optical heterodyne molecular spectrometry NICE-OHMS ; accuracy;

    Abstract : Laser spectroscopic techniques have, during the last decades, demonstrated an extraordinary capability for sensitive detection of molecular constituents in gas phase. Since spectra from such techniques constitute unique and characteristic signatures for each type of species, these techniques enable investigations of molecular structures as well as detection of the presence of species in a gas mixture. READ MORE

  5. 3. High-Sensitivity High-Resolution Diode Laser Spectroscopy in the Near-Infrared Region

    Author : Viacheslav G. Avetisov; Atomfysik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Fysicumarkivet A:1996:Avetisov;

    Abstract : High-resolution spectroscopy measurements have been performed using near-infrared diode lasers. Special emphasis was placed upon high accuracy absorption lineshape measurements, which provide the basis for quantitative gas analysis. For this purpose, relevant spectral characteristics of the radiation emitted by diode lasers were studied. READ MORE

  6. 4. Optical Frequency Comb Fourier Transform Spectroscopy

    Author : Alexandra C. Johansson; Aleksandra Foltynowicz; Ove Axner; Jürgen Röpcke; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Optical frequency comb spectroscopy; Fourier transform; molecular absorption dispersion; fysik; Physics;

    Abstract : Fourier transform spectroscopy (FTS) based on optical frequency combs is an excellent spectroscopic tool as it provides broadband molecular spectra with high spectral resolution and an absolutely calibrated frequency scale. Moreover, the equidistant comb mode structure enables efficient coupling of the comb to enhancement cavities, yielding high detection sensitivity. READ MORE

  7. 5. Fiber-laser-based noise-immune cavity-enhanced optical heterodyne molecular spectrometry

    Author : Aleksandra Foltynowicz; Ove Axner; Weidong Chen; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; absorption spectrometry; frequency modulation; cavity enhancement; NICE-OHMS; Laser frequency stabilization; fiber laser; Fabry-Perot cavities; sub-Doppler spectroscopy; trace gas detection; Physics; Fysik; Molecular physics; Molekylfysik; fysik; Physics;

    Abstract : Noise-immune cavity-enhanced optical heterodyne molecular spectro-metry (NICE-OHMS) is one of the most sensitive laser-based absorption techniques. The high sensitivity of NICE-OHMS is obtained by a unique combination of cavity enhancement (for increased interaction length with a sample) with frequency modulation spectrometry (for reduction of noise). READ MORE