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SC²S Colloquium - June 30, 2016

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Date: June 30, 2016
Room: 01.06.020
Time: 10:00 am, s.t.

Petar Tzenov, Michael Riesch: Modelling and Simulation of Quantum Cascade Lasers for Frequency Comb Generation

In the first part of this presentation we will give a brief introduction to our research activities and outline the interdisciplinary nature of our work.

In the group of Computational Photonics at the TUM, our research activities involve the theoretical modelling and simulations of quantum cascade lasers (QCLs) for frequency comb generation. After we give a brief introduction to QCLs and frequency combs, we will present the main models that we use and constantly strive to improve, which are namely stochastic electron transport simulations using a Monte-Carlo approach (implemented on Fortran) and light-matter interaction simulations based on coupled density matrix/Maxwell’s, i.e. Maxwell- Bloch, equations systems (C++ & Matlab). Both models are of a high degree of complexity and require a considerable computational effort until convergence is reached. Furthermore, there are strict physical constraints that need to be satisfied at all time in our simulations which necessitates the usage of suitably chosen numerical methods. We will mainly focus on the discretization and implementation of the Maxwell-Bloch system and discuss the approximations that we employ, current results and standing issues to be resolved.

In the second part of the colloquium a more detailed description of a GPU implementation of the Maxwell-Bloch equations will be presented. We will discuss the numerical methods used and their parallelization potential. Then we will examine the most critical parts, i.e. implementation bottlenecks, in greater detail. Finally, we conclude with a performance evaluation, the currently unresolved issues, and the outlook on future developments.

Outline

  1. Introduction to quantum cascade lasers (QCLs) and frequency combs
  2. Modelling approaches:
    1. Stochastic carrier transport simulation using ensemble Monte-Carlo method - algorithm outline and technical challenges
    2. Light-matter interaction simulations using coupled multiple level density matrix/Maxwell's equations. Numerical issues and computational load
  3. Results and future outlook
  4. Possible topics for student projects
  5. Parallelization of the Maxwell-Bloch equations with CUDA (Michael Riesch)