3D Vectorial Time Domain Computational Integrated Photonics

Abstract

Introduction/BackgroundThe design of integrated photonic structures poses considerable challenges. 3D-TimeDomain design tools are fundamental in enabling technologies such as all-optical logic, photonic bandgap sensors, THz imaging, and fast radiation diagnostics.Such technologies are essential to LLNL and WFO sponsors for a broad range of applications: encryption for communications and surveillance sensors (NSA, NAI and I-DIV/PAT); high density optical interconnects for high-performance computing (ASCI); high-bandwidth instrumentation for NIF diagnostics; micro-sensor development for weapon miniaturization within the Stockpile Stewardship and DNT programs; and applications within HSO for CBNP detection devices.While there exist a number of photonics simulation tools on the market, they primarily model devices of interest to the communications industry. We saw the need to extend our previous software to match the Laboratory's unique emerging needs. These include modeling novel material effects (such as those of radiation induced carrier concentrations on refractive index) and device configurations (RadTracker bulk optics with radiation induced details, Optical Logic edge emitting lasers with lateral optical inputs). In addition we foresaw significant advantages to expanding our own internal simulation codes: parallel supercomputing could be incorporated from the start, and the simulation source code would be accessible for modification and extension.This work addressed Engineering's Simulation Technology Focus Area, specifically photonics. Problems addressed from the Engineering roadmap of the time included modeling the Auston switch (an important THz source/receiver), modeling Vertical Cavity Surface Emitting Lasers (VCSELs, which had been envisioned as part of fast radiation sensors), and multi-scale modeling of optical systems (for a variety of applications).We proposed to develop novel techniques to numerically solve the 3D multi-scale propagation problem for both the microchip laser logic devices as well as devices characterized by electromagnetic (EM) propagation in nonlinear materials with timevarying parameters. The deliverables for this project were extended versions of the laser logic device code Quench2D and the EM propagation code EMsolve with new modules containing the novel solutions incorporated by taking advantage of the existing software interface and structured computational modules.Our approach was multi-faceted since no single methodology can always satisfy the tradeoff between model runtime and accuracy requirements. We divided the problems to be solved into two main categories: those that required Full Wave Methods and those that could be modeled using Approximate Methods. Full Wave techniques are useful in situations where Maxwell's equations are not separable (or the problem is small in space and time), while approximate techniques can treat many of the remaining cases.For both approaches we started by enhancing existing software. EMSolve began as a parallel finite-element time-domain (FE...