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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 47785 (05)
- University: Sharif University of Technology
- Department: Electrical Engineering
- Advisor(s): Faez, Rahim
- Abstract:
- Graphene, a monolayer carbon-atomic honeycomb lattice crystal, has attracted attention due to its peculiar carrier transport properties owing to the gapless energy spectrum. Due to lack of applicable light source in terahertz (THz) band, further researches to finding materials that are suitable for semiconductor lasers in this band to be continued. In this thesis, the population inversion possibility that is the first provision of laser operation, was analyzed in graphene optical pumping situation. The analysis was done by numerical solving of carrier concentration and energy density relations.As a result of this analysis population inversion is obtained when the stimulation square pulse has intensity over threshold, and pulse photon energy value is available. For example, assuming that the radiation pulse on grapheme has pulse width Δt = 100fs, and photon energy ħΩ = 0.8eV, and intensity at least I = 107W/cm2, the population inversion in the picosecond time scale is obtainable. With lower photon energy, pulse intensity threshold is reduced and the minimum frequency at which the negative dynamic conductivity achieved is also reduced.Then achieving to negative gain that is the next essential factor to having laser was studied. Afterward semiconductor laser rate equations was analyzed and simulated for this material and the results show emission of photons in a short time
- Keywords:
- Graphene ; Lasers ; Gain ; Simulation ; Rate Equations ; Population Inversion
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