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Archivio digitale delle tesi discusse presso l’Università di Pisa

Tesi etd-06012019-160135


Tipo di tesi
Tesi di laurea magistrale
Autore
CONTE, GLORIA
URN
etd-06012019-160135
Titolo
Terahertz quantum cascade lasers in coupled whispering-gallery microcavities
Dipartimento
FISICA
Corso di studi
FISICA
Relatori
relatore Prof. Tredicucci, Alessandro
tutor Dott. Pitanti, Alessandro
Parole chiave
  • exceptional points
  • microresonators
  • quantum cascade laser
  • terahertz
Data inizio appello
24/06/2019
Consultabilità
Non consultabile
Data di rilascio
24/06/2089
Riassunto
This thesis work describes the modelling, fabrication and characterization of a THz quantum cascade laser (QCL) whose resonant cavity is composed of whispering-gallery mode resonators combined with a linear dipole antenna. This peculiar configuration, when properly balanced by placing two microdisks in close proximity and connected by a suspended metallic bridge, allows to achieve vertical light emission; it represents a challenging task for THz QCLs, primarily originating from the electronic selection rules and subwavelength vertical confinement of light in double-metal waveguides.
In particular, I introduced an improved geometry for the electrical connection of the resonator, by considering a separate feeding of the two microdisks. This would simplify the device fabrication and, most interestingly, would be an ideal platform to investigate "exceptional points", obtained when the device is operated in full spatial and time symmetry. Changing the bias, the time-symmetry of the device can be modified, switching in and out of the conditions for the exceptional point, which is accompanied by a strong modification of the laser far field emission. The possibility to dynamically control the output beam, jointly with the expected high quality factor and low current threshold, make the device under consideration very promising for the development of miniaturized and monolithic THz sources.
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