Two-dimensional photonic lattices with a low-index defect have been studied. Simulations demonstrate that this type of structure has potential for realizing single-spatial mode operation from a relatively large emitting aperture, making it ideal for fiber coupling applications. A 2-D finite difference model is used to calculate the radiation loss of the modes in various low-index defect based two-dimensional photonic lattices. The simulation results are also compared to the results from a comprehensive the 3-D bi-directional beam propagation model. These calculations have been used to guide mask design and the experimental realization of the defect VCSEL devices.
Antiresonant reflecting optical waveguide (ARROW) vertical cavity surface emitting lasers (VCSELs) are designed for high power single mode operation. Scalar wave and finite-difference time domain (FDTD) studies indicate large modal discrimination in favor of the fundamental mode for large aperture (8 um) ARROW VCSELs. The modal discrimination mechanisms are identified through the total modal loss and quality factor calculations including polarization dependence. A novel design is presented, utilizing metal absorption loss to help suppress higher-order modes.
Modal behavior of a 2-D (square lattice geometry) antiguided vertical cavity surface emitting laser (VCSEL) array was studied by 3-D bi-directional beam propagation method. Above threshold operation of leaky modes was simulated using multiple iterations. Besides, a method based on functions of Krylov’s subspace, was developed to find a number of array optical modes in a VCSEL array with gain and index distributions established by the oscillating mode. In calculations, both Fourier and space variable descriptions of beam propagation were combined. The FFT technique was used for calculations of the Fourier image and the original. Conditions are found for favorable lasing of the in-phase mode providing high laser beam quality. Experimentally realized 5x5 laser array was studied numerically.
The 2-D antiguided array results from shifting the cavity resonance between the element and inter-element regions and is fabricated by selective chemical etching and two-step metalorganic chemical vapor deposition (MOCVD) growth. In-phase and out-of-phase array mode operation is observed from top-emitting rectangular arrays as large as 400 elements, depending on the inter-element width, in good agreement with theory.