Simulation is a very useful tool for engineering and design of devices. In our labs we use LightTools - an optical engineering and design software - for designing our optoelectronic devices and components. This ray tracing software is also extremely helpful for verification of ideas and predicting results. This software has been instrumental in design of our triple-layer omni-directional reflectors, distributed Bragg reflectors, anti-reflection coatings, device geometries etc. We have also been able to demonstrate losses due to whispering gallery modes in LEDs, enhancement in extraction by using TiO2 nano-particle loaded high refractive-index epoxy and optimize extraction from phosphor-based LEDs. Ray tracing simulations provide strong foundations in our projects such as high extraction efficiency packaging and device design, very high reflectivity mirrors for LEDs etc. For device simulation we use is ATLAS SILVACO. This 2D device simulation software accurately characterizes physics-based devices for electrical, optical and thermal performance. This saves time and resources required for actual fabrication of each different device structure and geometry and also provides a good starting point for actual device fabrication.