A numerical method for global optimization of semiconductor intersubband laser/detector performance parameters is presented. The single-band effective-mass Schroedinger equation is solved by employing the argument principle method (APM) to extract both the bound (B) and quasibound (QB) eigen-energies of the quantum heterostructure. APM is combined with a simulated annealing (SA) algorithm to determine a set of device design parameters such as potential barrier height V i , layer thickness d i , applied bias V Bias , for which the intersubband device performance is within a predetermined convergence criterion. The method presented incorporates the energy-dependent effective mass of electrons in nonparabolic conduction bands. The performance of the method is evaluated for the design of an asymmetric Fabry-Perot electron-wave interference filter (laser structure) and a dual-band quantum well infrared photodetector (QWIP). Results with and without nonparabolic effects are presented. In addition, results from the present method are compared to results obtained via the optimization technique based on super-symmetric quantum mechanics (SUSYQM) for the case of an optically-pumped quantum cascade (QC) laser. The present method is shown to improve the device performance beyond that obtained via SUSYQM optimization. Further, the present model can handle many optimization parameters and can incorporate fabrication constraints to achieve physically realizable devices.