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Modeling in Photonics

What is a Model?

Essentially, a model is a mental construction which is supposed to resemble some aspects of reality. Typically, it is used for acquiring a better understanding of reality, which then helps for making good decisions.

A model is always simpler than reality, so that we can better cope with the remaining level of complexity. Of course, it should not be over-simplified, i.e., it must properly describe certain aspects which are of interest in an investigation. The optimum type of model if often one which incorporates everything necessary but nothing more.

In technical areas, modeling starts with some thoughts and ideas, which are then condensed to more formal structures, involving certain quantities, mathematical equations, etc. Computers equipped with suitable software can be used for the corresponding calculations. Computer models simulate the behavior of real objects (e.g., buildings, cars, electronic circuits or lasers) and reveal not only expected outputs, but also the internal workings.

Examples for Models

Models are routinely used in many technical areas; some examples:

Application Area Type of Model Aspects to Investigate
Architecture small-scale artifact or computer model of a building
  • space for inhabitants and installations
  • distribution of light (sunlight, illumination)
  • energy flows
  • structural stability
Cars model of a car body
  • space for passengers
  • structural stability, safety in crashes
  • dynamic driving behavior
Electronics model of an electronic circuit
  • validation of functionality
  • influences of imperfections and tolerances of parts
  • operation with over- or under-voltage
Laser Technology model for a Q-switched laser with laser crystal, modulator and resonator
  • dynamics of pulse generation
  • power conversion efficiency
  • beam quality
  • effects of gain guiding, limited modulator speed, etc.

The next page gives you more concrete examples for models in laser technology.

General Purposes of Models

Modeling is not a purpose itself, but is done in order to obtain important benefits:

Purpose Examples in laser technology
Develop a clear understanding of how things work
  • power conversion in laser crystal or doped fiber
  • beam formation in a laser resonator
  • dynamics of pulse generation or amplification
Plan the construction of prototypes and final products
  • laser resonators
  • laser heads
  • pulse amplification systems
  • data transmissions systems
Analyze problems of existing or planned devices
  • poor beam quality
  • poor power conversion efficiency
  • instabilities
  • optical damage
Develop and analyze new ideas
  • new resonator design concepts
  • new pumping arrangements
  • new gain materials
  • new principles of pulse amplification

But why should you do such investigations on computer models rather than on the real objects?

Building and testing the real objects stays necessary – but is then based on prototype or product designs which result from a clear understanding. Don't build and test what cannot work anyway!

The Benefits

Typical achieved benefits of working with computer models are:

Such benefits are of crucial importance for the productivity e.g. of a laser development engineer or a scientist in laser research. Both need to understand exactly how things work and how to effectively optimize them.

For more details, see also our tutorial on modeling.

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