History
The development of the OPTOS formalism started in 2015 at theOPTOS simulation procedure
One key aspect of OPTOS simulations is the division of the modeled system into interface and propagation regions. The light redistribution properties are calculated with the most appropriate method for each interface individually and depending on the relevant structure dimension. Large scale structures can for example be modeled via ray tracing while for interfaces with structure dimensions in the range of the wavelength wave optical approaches like RCWA,System description
The discretization of the complete angular space into a fixed number of angle channels, as second key aspect of the OPTOS formalism, allows representing the angular power distribution within the system by a vector v which consists of one entry for each angle channel. The value of the entry is the power fraction of the corresponding angle channel with respect to the total incident power.Interface interaction
The light redistribution properties of an interface are represented by the so-called reflection and transmission matrices, R and T. They store for each of the angle channels the redistribution information into other angle channels for light incident onto a certain interface with a certain wavelength. There are in total four different redistribution matrices for each interface, characterized by the incidence direction as well as reflection or transmission redistribution.Propagation through the sheet
The incoherent propagation of light through the sheet can also be represented by a matrix. If no light redistribution takes occurs on the path, the propagation matrix D is a diagonal matrix. The single entries consist of the Lambert-Beer absorption factor, including cosine of the polar angle and the absorption coefficient of the respective material.Calculation of optical properties
Using the pre-calculated matrices described above, optical properties like reflectance, transmittance or absorptance within the sheet can be calculated via matrix multiplications –4and can be performed within seconds or minutes using a standard personal computer. Also a depth-dependent absorption profile can be calculated. This is of special importance for the subsequent electrical simulation of structured silicon solar cells.OPTOS simulation characteristics
Strengths
* Versatility – Optical systems with interface structures operating in different optical regimes can be accurately simulated. The redistribution properties of each interface are modeled individually with the most suitable method. * Efficiency - The re-usability of the redistribution allow for the very fast simulation of different structure combinations, sheet thickness variations and the optical analysis with respect to different angles of incidence. * Linear polarization can be taken into account by exchanging each entry of the power distribution vector with two entries, one for each polarization direction. Each matrix entry has to be exchanged with a two by two matrix taking also the redistribution between different polarization directions into account.Limitations
OPTOS couples redistribution properties of different interfaces. If there is no accurate modeling technique to calculate redistribution matrices, such interfaces cannot be included in OPTOS. OPTOS models the propagation through the sheet incoherently. If the sheet thickness becomes very low and interference effects play a significant role, this needs to be handled coherently and not as “thick” sheet. However, as coherently modeled sub-system, it can be included in OPTOS as effective interface. Circular or elliptical polarization effects are not taken into account as all phase information is neglected during the propagation.Application Examples
The main application of OPTOS has so far been the simulation of: *References
{{reflistExternal links
OPTOS page at Fraunhoer ISE website (includes documentation and download of basic version)