Volume 97, Issue 7, 01 April 2005
Index of content:
- LASERS, OPTICS, AND OPTOELECTRONICS
97(2005); http://dx.doi.org/10.1063/1.1863425View Description Hide Description
A theoretical study of scattering and interference of waves in one-dimensional (1D) Bragg structures, also known as photonic band-gap(PBG)structures, based on multiconductor waveguides is presented. The case of small perturbations of the waveguide walls was analyzed. Using the coupled-wave theory the expression for the wave-coupling coefficient was generalized. The possibility of controlling the scattered wave polarization and the band gap locations in such structures due to the constructive and destructive interference of the waves was demonstrated. It was shown that such control can be achieved by adjusting the relative phase of the 1D periodic perturbations with respect to each other. As an example a 1D structure based on a coaxial waveguide was studied using three-dimensional computer simulations and coupled-wave theory. The dispersion diagrams are presented and the dependence of the reflected wave structure on the phase between the corrugations analyzed and discussed. To demonstrate the validity of the theory the results obtained for the basic coaxial model with a single corrugated conductor are compared with the experimental results observed.
97(2005); http://dx.doi.org/10.1063/1.1870094View Description Hide Description
Using the finite-difference-time-domain method, the near-field optical distribution and properties of Sb thin film thermal lens are calculated and simulated. The results show as follows. Within the near-field distance to the output plane of thermal lens, the spot size is approximately , and its intensity is greatly enhanced, which is higher than that of incident light. The spot shape gradually changes from ellipse to round at the distance of more than to the output plane. The above-simulated results are further demonstrated by the static optical recording experiment.
97(2005); http://dx.doi.org/10.1063/1.1874299View Description Hide Description
An analysis technique is developed for the purpose of determining which semiconductor laser parameter is responsible for degradation. The technique allows one to distinguish between the two modes of degradation: (1) a reduction in electrical carrier injection efficiency or (2) an increase in optical loss. In the case of increasing optical loss, one can determine where longitudinally along the waveguide this degraded optical loss is occurring. Experimentally, we apply the technique to an earlier generation of high-power, single-mode 14XX-nm pump lasers under various accelerated aging conditions.
97(2005); http://dx.doi.org/10.1063/1.1866473View Description Hide Description
In this paper, a two-dimensional square photonic crystal(PC) with superconductor cylinders is proposed to realize tunable negative refraction. Based on the dependence of the superconductors’ permittivity on temperatures,photonicband structures thus negative refraction could be tuned by temperatures, whereby the refractive angle could be scanned from positive to negative. The feasibility of the PC operating in infrared and visible regions was discussed. The tunability resulted from the lattice, superconductors, operating frequency, and incident angle may lead the PC to great promise in photoelectronics and superconductor electronic applications.
97(2005); http://dx.doi.org/10.1063/1.1873059View Description Hide Description
The measurement of propagation loss based on the Fabry–Pérot transmission fringes is a powerful tool for the characterization of single-mode optical waveguides. This method is well established for lithium niobate waveguides, but its implementation with semiconductor devices is more delicate. A method to extend this technique to the case of multimode semiconductorwaveguides is presented. Our procedure involves Fabry–Pérot measurements on a large spectral range, in order to find an interval where multimode effects do not alter the loss measurement. Two experimental examples are given, showing also the domain of validity of this approach.