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Spectroscopie dans le domaine temporel et non-linéarités optiques résonantes des lasers à cascade quantique térahertz

Abstract : The terahertz (THz) range is a region of the electromagnetic spectrum that lies between optical and electronic techniques to generate and detect radiation. It is also know as the THz "gap" because of a critical lack of devices whereas potential applications are wide ranging. This thesis comprises three research areas, all related to a promising THz source : the Quantum Cascade Laser (QCL). QCLs are unipolar lasers based on semiconductor heterostructures where emission relies on electron relaxation between con ned states in the conduction band i.e. intersubband transitions. In the rst part of this thesis, a THz time domain spectroscopy (TDS) system was developed and optimised that would be adapted to the study of the spectral gain of THz QCLs. Speci cally THz pulse sources (photoconductive antennas) for THz TDS were realised allowing access to a large frequency bandwidth. This system development was used to access the spectral gain of THz QCLs, a key parameter of the device, and applied in particular to the study of heterogeneous THz QCLs (i.e. comprising more than one zone active for broadband emission). The investigations permitted the limiting factors to be determined, improvements in the designs and a resulting broad gain with laser operation at two frequencies simultaneously. Finally, the resonant non-linear optical properties of THz QCLs were studied. An enhancement of the non-linear susceptibility was demonstrated by bringing an injected the NIR beam in resonance with interband transitions of the QCL. Combined with the large intracavity THz power of the QCL, we show that it possible to convert the THz QCL emission onto a near-infrared optical carrier with large e ciencies (0.12%).
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Contributor : Julien Madéo Connect in order to contact the contributor
Submitted on : Thursday, January 19, 2012 - 11:16:04 AM
Last modification on : Thursday, March 17, 2022 - 10:08:15 AM
Long-term archiving on: : Tuesday, December 13, 2016 - 11:33:31 PM


  • HAL Id : tel-00661325, version 1


Julien Madéo. Spectroscopie dans le domaine temporel et non-linéarités optiques résonantes des lasers à cascade quantique térahertz. Physique Générale [physics.gen-ph]. Université Pierre et Marie Curie - Paris VI, 2011. Français. ⟨NNT : ⟩. ⟨tel-00661325⟩



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