Researches Of Spectral Structures And Field Distributions Of Phtotonic Crystal Auantum Well

Photonic quantum well (PQW) structures can be constructed in a way similar to semiconductor QW structures. PQW structures are also composed by wells and barriers which represent different one-dimension, two-dimension or three-dimension photonic crystals (PCs) respectively, just like that of semiconductor QW structures. These provide the diversifications of PQW structures, functions and characteristics.The theoretical basises for PC devices are photonic band gap (PBG) and photonic localization. In this paper, we have construced many good PQW structures with fine optical characteristics based on the finite-difference time-domain method (FDTD), and have discussed the physical origins supporting these fine optical characteristics. The main conclusions and originality innovations are as follows:(1) The computational procedures with formidable function and high precision based on FDTD have been compiled, and the accuracies of algorithms and procedures are demonstrated.(2) The graded-index PQW structures are constructed, the feasibility of finely modulating the confined energy levels is demonstrated, and the significance of this modulation by using PQW structures is discussed.(3) The concepts of open-cavity and closed-cavity PQW structures are introduced, and the measures which can improve the optical characteristics of two-dimension PQW structures are presented. Their transmission spectra and optical field distributions indicate that, the well in the open-cavity single PQW structure is a traveling-wave resonantor, while the well in the closed-cavity single PQW structure is a standing-wave resonator with stronger field localization of light. This firmly confirm our conjecture that closed-cavity could confine the optical field more strongly.(4) The effect of spectral splitting in one- and two-dimension multiple PQW (MPQW) structures is researched, and the regularity of splitting is analyzed. It is found that the spectral splitting is induced by the intercoupling effect among the wells, whose features are determined not only by the well number but also the parameters of barriers or wells. It may be applied widely in the fields of super dense wavelength division multiplexing for optical communication and the precise optical measurement.(5) The optical field distributions in the two-dimension open-cavity and closed-cavity MPQW structures are systematically studied, and the detailed explanations are provided based on the coupled-mode theory and wave-function theory. The computed results indicate, both the well and barrier thicknesses have a marked influence on the optical field distribution of MPQW structures. These results would have important values for disclosing the movement regularity of photons in the quantized systems.(6) The influence on PBG of permeability is systematically investigated. The magnetic material PQW structures based on the non-magnetic material PQW are proposed. It is found the optical transmittance of the magnetic PQW is close to 1, and energy loss is less. Compared with the closed-cavity PQW structures, the device's volume can be reduced, the degree of free regulation of energy band project can be increased, and more photon bound states can be obtained. It is also found that the well in the magnetic PQW strcture is a standing wave resonator, and the capabilities for them to capture photons are strong.