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Abstract
Modeling of nanocavity light emitting semiconductor devices is done using the semiconductor laser rate equations with spontaneous and stimulated emission terms modified for Purcell enhanced recombination. The modified terms include details about the optical and electronic densityofstates and it is argued that Purcell enhancement should also be included in stimulated recombination term, contrary to the common practice in the literature. It is shown that for quantum well devices, the Purcell enhancement is effectively independent of the cavity quality factor due to the broad electronic densityofstates relative to the optical densityofstates. The low effective Purcell eect for quantum well devices limits the highest possible modulation bandwidth to a few tens of gigahertz, which is comparable to the performance of conventional diode lasers.
Compared to quantum well devices, quantum dot devices have narrower electronic densityofstates and are not affected by the reduction of the Purcell enhancement to the same degree. The highest modulation bandwidth is found for
below threshold operation, where the bandwidth is not cavitylimited.
Using finitedifference timedomain methods, systems of passive, coupled photonic crystal nanocavity structures are simulated. The resonance frequencies of inphase and outofphase coupled quadrupole modes in rectangular photonic crystal H1 cavities are extracted and are found to vary nontrivially with the intercavity separation. A qualitative explanation is given in terms of the inplane mode profiles. Fareld emission patterns for the structures are calculated based on the finitedierence timedomain simulations. It is found that only systems with an even number of holes separating the cavities show clear signs of being coupled. This nontrivial coupling behavior is useful for design of coupled systems.
A tightbinding description for coupled nanocavity lasers is developed and employed to investigate the phaselocking behavior for the system of two coupled cavities. Phaselocking is found to be critically dependent on exact parameter values and to be dicult to achieve for systems with large linewidth enhancement factors and low Purcell enhancement such as quantum well based lasers.
Realistic numbers for the coupling strength are extracted from finitedierence timedomain simulations.
Compared to quantum well devices, quantum dot devices have narrower electronic densityofstates and are not affected by the reduction of the Purcell enhancement to the same degree. The highest modulation bandwidth is found for
below threshold operation, where the bandwidth is not cavitylimited.
Using finitedifference timedomain methods, systems of passive, coupled photonic crystal nanocavity structures are simulated. The resonance frequencies of inphase and outofphase coupled quadrupole modes in rectangular photonic crystal H1 cavities are extracted and are found to vary nontrivially with the intercavity separation. A qualitative explanation is given in terms of the inplane mode profiles. Fareld emission patterns for the structures are calculated based on the finitedierence timedomain simulations. It is found that only systems with an even number of holes separating the cavities show clear signs of being coupled. This nontrivial coupling behavior is useful for design of coupled systems.
A tightbinding description for coupled nanocavity lasers is developed and employed to investigate the phaselocking behavior for the system of two coupled cavities. Phaselocking is found to be critically dependent on exact parameter values and to be dicult to achieve for systems with large linewidth enhancement factors and low Purcell enhancement such as quantum well based lasers.
Realistic numbers for the coupling strength are extracted from finitedierence timedomain simulations.
Original language  English 

Place of Publication  Kgs. Lyngby, Denmark 

Publisher  Technical University of Denmark 
Number of pages  156 
Publication status  Published  2012 
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 1 Finished

Modeling of Coupled NanoCavity Lasers
Skovgård, T. S., Mork, J., Gregersen, N., Abram, I. & Willatzen, M.
Technical University of Denmark
01/10/2008 → 19/04/2012
Project: PhD