Computational optoelectromechanics and its application to MEMS VCSELs

Abstract

Vertical-cavity surface-emitting lasers (VCSELs) have been research extensively as key components for next-generation of wireless communication, computing, processing, switching and optical devices. Conventional VCSELs integrate two oppositely doped distributed Bragg reflectors (DBR) with a cavity layer between them. In the center of the cavity layer there is an active region with multiple quantum wells. Current is injected into the active region using oxide or proton-implanted apertures. Recent research and developments have been progressed to the tunable, long-wavelength, and multiple-wavelength MEMS-based electrically- and optically-pumped VCSELs. These MEMS VCSELs integrate a bottom n-DBR (for example, GaAs-AlGaAs), a cavity layer with the active region (for example, InGaAS), and a top mirror. The top mirror integrates p-DBR (oxidation and sacrificial layers, AlAs, AlGaAs) -- air gap -- top n-DBR suspended above the laser cavity and controlled (displaced or bent) by the nano- or microscale actuators. The current is fed through the p-DBR. Hence, optoelectronics and microelectromechics are examined for MEMS VCSELs. In contrast, the optically-pumped VCSLEs with membrane MEMS integrate n-DBR, cavity layer with the active region, p-DBR, sacrificial layer (for example, AlGaAs) and top mirror (quarter-wave GaAs layer). Usually, the wavelength of tunable VCSELs can be varied within 10 - 30 nm increments. To optimize MEMS VCSELs, far-reaching research and developments must be carried out. Recently, novel MEMS VCSELs topologies and configurations have been devised. These MEMS VCSELs must be modeled, analyzed, and optimized. The computer-aided-design will lead to essential improvement of lasers optimizing their performance. High-fidelity modeling, heterogeneous simulation, data-intensive analysis and synergetic design of MEMS VCSELs are part of a newly emerging field of computational optoelectromechanics. In fact, high-fidelity modeling is an important part in synthesis and design of affordable high-performance MEMS VCSELs with the desired performance and reliability. The basic equations to model VCSELs are found using the quantum mechanics, quantum electromagnetic field theory, Maxwell's and Navier-Stokes equations. To derive the equations of motion for nano- or microactuators, the functional density concept is used to find the force, and Newtonian mechanics allows one to derive the differential equations to integrate mechanical dynamics. This paper focuses on the development of the theory of computational optoelectromechanics and its application to computer-aided design of MEMS VCSELs. The modeling, simulation, analysis and design results are reported and illustrated.