This paper describes a novel approach to the problem of model order reduction (MOR) of very large nonlinear systems. We consider the behavior of a dynamic nonlinear system as having two fundamental characteristics: a global behavioral "envelope" that describes major transformations to the state of the system under external stimuli and a local behavior that describes small perturbation responses. The nonlinear low order envelope function is generated by using the remainders from the coalescence of projection bases taken through a space-state sample. A behavioral model can then be expressed as the superposition of these two descriptions, operating according to the input stimuli and the current state value. The global behavior describes major transformations to the state of the system under external stimuli and the local behavior describes small perturbation responses. Local effects are captured by regions through a set of linear projections to a reduced state-space while global effects are captured by examining the non-commonalty among these projections. These "remainders" are used to build a modulation function that will generate the required dynamic changes in the common linear projection. The advantage of the envelope representation for strongly nonlinear systems is that it simplifies the complexity of the model into a two-part problem. Depending on the complexity or cost of the behavioral separation procedure, it can be repeated recursively

We present our system-level co-simulation environment for mixed domain microsystems. The environment provides synchronization and co-simulation between the Chatoyant MOEMS (micro-electro mechanical systems) simulator and ModelTech ModelSim. By using shared memory IPC (inter-process communication) and PDES (parallel discrete event simulation) techniques, we achieve two orders of magnitude speedup over standard pipe/socket communication.

We present a component-based multi-level mixed-signal design and simulation environment for microsystems spanning the domains of electronics, mechanics, and optics. The environment provides a solution to the problem of accurate modeling and simulation of multi-domain devices at the system level. This is achieved by partitioning the system into components that are modeled by analytic expressions. These expressions are reduced via linearization into regions of operation for each element of the component and solved with modified nodal analysis in the frequency domain, which guarantees convergence. Feedback among components is managed by a discrete event simulator sending composite signals between components. For electrical, and mechanical components, interaction is via physical connectivity while optical signals are modeled using complex scalar wavefronts, providing the accuracy necessary to model micro-optical components. Simulation speed vs. simulation accuracy can be tuned by controlling the granularity of the regions of operation of the devices, sample density of the optical wavefronts, or the time steps of the discrete event simulator. The methodology is specifically optimized for loosely coupled systems of complex components such as are found in multi-domain microsystems.

As designers become more aggressive in introducing optical components to micro-systems, rigorous optical models are required for system-level simulation tools. Common optical modeling techniques and approximations are not valid for most optical micro-systems, and those techniques that provide accurate simulation are computationally slow. In this paper, we introduce an angular frequency optical propagation technique that greatly reduces computation time while achieving the accuracy of a full scalar formulation. We present simulations of a diffractive optical MEM grating light valve to show the advantages of this optical propagation method and the integration of the technique into a system-level multi-domain CAD tool.

Chatoyant models free-space opto-electronic components and systems and performs simulations and analyses that allow designers to make informed system level trade-offs.Recently, the use of MEM bulk and surface micro-machining technology has enabled the fabrication of micro-optical-mechanical systems.This paper presents our models for diffractive optics and new analysis techniques which extend Chatoyant to support optical MEMS design.We show these features in the simulation of two optical MEM systems.