Design and Monte Carlo Simulation of a LED-based Optic Coupler
The design of a multi-wavelength light source used to measure the external quantum efficiency of solar cells is presented. This low-cost optic coupler is based on the concept of integrating sphere and on the use of LEDs pulsing at different frequencies followed by a Fourier transformation of the current generated in the device under test. To obtain an accurate simulation model of the optic coupler experimental measurements were employed. Two algorithms based on Monte Carlo raytracing were tested. The first one uses a uniform random selection of the director angle and, depending on it, assigns a power to simulated rays. The second approach samples this angle randomly from a given distribution and uses an equal power for all rays. Both methods were compared in terms of their repeatability and dispersion.
keywords: Light-emitting diodes, raytracing, spectral response