Method for designing photonic-crystal distributed-feedback and distributed bragg-reflector lasers

摘要

A method for calculating the beam quality and output wavelength spectrum of a photonic crystal distributed feedback laser includes the steps of calculating at least two coupling coefficients and forming a characteristic matrix; repeating the following steps at spaced increments of time until a steady state solution is reached: repeating the following steps for one of the incremental cavity lengths: calculating a gain change and a modal refractive index change for the laser waveguide structure for one incremental stripe width; calculating a spontaneous emission term for the gain change; calculating a gain roll-off term for the gain change; applying the gain change, the modal refractive index change, the spontaneous emission term, and the gain roll-off term to at least two forward-propagating beams and at least two backward-propagating beams for the one incremental stripe width; performing a Fourier transformation with respect to the one incremental stripe width to yield a plurality of diffraction terms; adding the diffraction terms to the characteristic matrix; propagating the two forward-propagating beams by the incremental cavity length from a first section to a succeeding and adjacent second section with the characteristic matrix; propagating the two backward-propagating beams by the incremental cavity length from the second section to the first section with the characteristic matrix; performing an inverse Fourier transformation with respect to the stripe width; and applying at least one boundary condition to a facet of the laser configuration for each time increment. The steady-state solution is used as the basis for evaluating the beam quality and output wavelength spectrum corresponding to the design parameters, the additional design parameters, and the photonic crystal geometry of the laser configuration. The invention provides scientists with an approach to designing and building lasers that eliminates much of the time and resources otherwise needed in the building and testing of unsuccessful designs.