Crystal Waveguide Modes Research Articles

Modification of optical response in quantum dots embedded in a photonic crystal waveguide via photonic band engineering

ABSTRACTWe propose to use Purcell effect emerged at slow light regions in photonic crystal waveguide (PC-WG) modes for controlling the relaxation time of excited carriers in QDs. Straight GaAs PC-WGs including InAs-QDs with various lattice constants of PC were prepared in order to control the wavelength of the slow light in the PC-WG modes. PL measurements of the PC-WGs indicated enhancements of emission from QDs at the localized wavelength of slow light regions due to the Purcell effect. The enhanced emission peak wavelength was continuously shifted with the PC lattice constant. These results suggest that the PC-WG can be utilized to modify the spontaneous emission rate and carrier relaxation time of the embedded QD. This modification can be applied and useful for various QD-based optical devices as well as our proposed all-optical switching device based on PC-WG/QD.

Modes of Shallow Photonic Crystal Waveguides: Semi-Analytic Treatment

We investigate the formation of photonic crystal waveguide (PCW) modes within the framework of perturbation theory. We derive a differential equation governing the envelope of PCW modes constructed from weak perturbations using an effective mass formulation based on the Luttinger-Kohn method from solid-state physics. The solution of this equation gives the frequency of the mode and its field. The differential equation lends itself to simple analytic approximations which reduce the problem to that of solving slab waveguide modes. By using this model, we demonstrate that the nature of the projected band structure and corresponding Bloch functions are central to the behaviour of PCW modes. With this understanding, we explain why the odd mode in a hexagonal PCW spans the entire Brillouin zone while the even mode is cut off.

Improved directional emission by resonant defect cavity modes in photonic crystal waveguide with corrugated surface

Directional emission of light from a photonic crystal (PC) waveguide can be observed by adding periodically corrugated surface as reported in Moreno et al. (Phys. Rev. B 69:121402, 2004). In this paper, it is being further shown by numerical simulation with finite-difference time-domain method that adding point defects to the adjacent layer of surface corrugations helps to improve directional emission. The coupling between the resonant cavity modes and surface modes is believed to account for this effect.

Horn waveguide couplers for interfacing between two-dimensional photonic crystal and single mode planar dielectric waveguides

We propose and optimize the horn waveguide couplers based on distributed Bragg reflector waveguide for coupling between two-dimensional dielectric cylinder photonic crystal waveguide and single mode planar dielectric waveguide and evaluate their transmission efficiency using the finite difference time domain method. The simulation results show that the power transmission efficiency is over 98% in a large part of the frequency range of the guided mode of photonic crystal waveguide. The highest transmission efficiency is 99.85%.

Study of elastoplastic deformation for cylindrical shells with axial shock loading

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