For the butt-joint coupling between a single mode fiber (SMF) and a single mode dielectric slab waveguide (SMDSW) with a spherical fiber microlens (SFML), because the SMF and the rectangular-section SMDSW have different symmetry, it is difficult to calculate the coupling efficiencies using the traditional analytic method. In this paper, a Monte Carlo model of the coupler is proposed. This model incorporates the geometrical surface of both the SFML and the SMDSW, the relative position of the SMF and the SMDSW, and both the aberration and diffraction effects into consideration. The propagation characteristics of the coupler are simulated. And the coupling efficiencies and misalignment loss are investigated.
The focusing of the focused Gaussian beam by a spherical aberration micro-lens is investigated by Monte Carlo
simulation. This method takes into the images affected by the primary even higher orders aberration with no paraxial
approximation. The effect of the negative spherical aberration on the radial intensity distribution, spot size and focal shift
are discussed. The simulation results show that when the Gaussian beams are focused by a lens with spherical aberration,
the radial intensities distributions in the geometrical and best focal plane had two maxima, and the maxima point are not
located in the optical axis. And with the Fresnel number increasing, the simulation focal shift curve approach the curves
calculated by the formula for an aberration-free lens.
The diffraction properties of a silica-based etched diffraction grating are investigated by numerical simulation in threedimension.
The field distribution of the electromagnetic filed in the near and far away groove area, the diffraction
efficiency and spectral response of 8 channels are analyzed respectively. The numerical results show that the diffraction
angle is not satisfied the famous grating formula, the deviation of the diffraction angle is increasing with the diffraction
order. And when the groove depth is in the low and medium modulation region, the diffraction efficiency reaches over
90%, and the spectral response of an etched grating is uniform within the fiber communication spectrum range.
A novel dielectric band-pass filter with focusing function is presented. This filter is the cylindrical dielectric mirror
composed of one-dimensional photonic crystals. The transmission characteristic of the band-pass filter is investigated
using the finite-difference time-domain method. The numerical results show that only when the number of reflection
layers is larger than the corresponding least number, an incident beam with frequency located in the omnidirectional
reflection band can be reflected and focused efficiently. It is expected to be applied to highly dense photonic integrated
circuits after further research.
The diffraction properties for blazing -3 order of the perfectly conducting blazed gratings in the Littrow mounting under
the polarized incident beam is investigated by numerical simulation. The diffractive electromagnetic fields for S and P
polarized incident lights are calculated numerically using TDFD method. The field distribution of the electromagnetic
field in the near groove area is analyzed, and the polarization dependency of diffraction efficiency is studied. The
spectral characteristics in 1530~1566 nm range is given. It is proved that the efficiency for S polarized incident light is
higher than that of P polarized one and it is not sensitive to the blazed angle. The spectral characteristic is flat within the
fiber communication spectrum range.