Design of Single-Mode and Two-Color Fabry--PÉrot Lasers With Patterned Refractive Index

We describe a method of tailoring the laser spectrum of Fabry-Perot (FP) laser diodes using a spatially varying refractive index. The cavity geometry is determined by a perturbative transmission matrix calculation of the threshold gain of the longitudinal modes and solution of the corresponding inverse problem. Single-mode FP lasers with predetermined wavelength, and two-color FP lasers with predetermined mode spacing in the terahertz region are designed and experimentally demonstrated.