KALLISTOS

Using KALLISTOS, design cycle times of a new device can be dramatically reduced

Produced by LambdaTek, KALLISTOS is a novel optimization tool capable of automatically improving existing designs of photonic devices with minimum user intervention and is tightly integrated with Photon Design products.

Considerable work has gone into all aspects of the product, resulting in a tool incorporating state of the art optimization algorithms, combined with a powerful graphical user interface making it easy for the user to set up and run a design optimization calculation, and a comfortable visual interface which allows the user to fully explore the solutions found.

Much care was taken in making KALLISTOS as efficient as possible. For example, when calculating the sensitivities used by the local optimizer, KALLISTOS takes full advantage of the special structure of the wave equations describing light propagation through photonic devices.

  • Automatically improve your existing designs
  • Uses state of the art optimization techniques
  • Powerful, user-friendly graphical user interface
  • Complete flexibility with built-in function parser
  • Fault-tolerant
  • Tightly integrated with Photon Design products
  • Speed-optimized for design of photonic device

Platforms
PC: x86+x64: Win2000/XP/Vista, 1GB RAM, 2GHz or better recommended.


The Optimization algorithms and monitoring interfaces

Under the hood, KALLISTOS is equipped with several robust optimizers for global and local optimization of continuous functions.

Finding solutions to complex optimization problems can be a difficult task. In general there is no optimization algorithm that works in all cases. KALLISTOS comes with several efficient algorithms based on recent advances in mathematical optimization with complementing strengths:

Local Optimization
Efficient local descent routines. Ideal for large, computationally intensive structures, which can find an optimum within relatively few iterations

Global Optimization
Deterministic and stochastic global optimization techniques. These converge more slowly than the above, but are more likely, if not guaranteed, to find a global optimum

Optimization calculations can be very lengthy for complex 3D structures. The mathematical structure of the wave equations has been exploited by incorporating an analytical procedure for calculation of the sensitivities, essential to the optimization process. This and other improvements make KALLISTOS an optimized optimization tool for design of photonic devices.

Far from adopting a black box approach, KALLISTOS comes with powerful graphical monitoring interfaces for following the progress of multidimensional optimization calculations. These prove to be particularly useful for detecting potentially optimal designs when using a global optimizer. For example, the user can quickly locate a point of interest in the parameter space and "home in” on it with a local optimizer.


Example of using KALLISTOS with FIMMPROP:γ€€ OPTIMIZED TAPER DESIGN

We gave this to KALLISTOS... and got back this!

The device on the left is an ultra short (7mm) linear taper giving about 53% power transmission into the output fundamental mode. KALLISTOS was configured to seek a design with the same length, but with improved transmission. The result was the oddly shaped device on the right, giving over 90% transmission! This was a large problem involving dozens of parameters controlling the taper shape.


Example of using KALLISTOS with FIMMPROP:γ€€ OPTIMIZED S-Bend DESIGN

We gave this to KALLISTOS...             and got back this!

The device on the left shows two waveguides joined by an angled linear section. The losses are considerable, the power transmission into the output fundamental mode being only 35%. KALLISTOS was configured to seek a design with the same length, but with improved transmission. The result was the "s-bend" on the right. Note how the optimizer automatically chose to include offsets at the waveguide interfaces!


Example of using KALLISTOS with CRYSTALWAVE:γ€€ OPTIMIZED PHOTONIC CRYSTAL

We gave this to KALLISTOS... ...

... and got back this!

KALLISTOS was used to automatically design the best possible configuration for the device in the above picture. The aim was to maximise power transmission into the LHS branches for a given incoming field in RHS input waveguide. In this huge project the variable parameters were the holes marked in green in the second picture and the end offsets and width of the injector. Within a few hours KALLISTOS was able to find a configuration with almost perfect transmission!

For the optimization of the injector, a Local Optimization method was used, and the Global Optimization method was used for the optimization of the photonic crystal. The objective being not only high efficiency, but also wide bandwidth was taken into account for this optimization process.

This work was done under the European IST project PICCO. Lab measurements of the manufactured design yielded World record bandwidths (ref. University of St. Andrews, U.K.)