One can often use analytical methods to determine the optical response of a multilayer stack instead of direct simulations of Maxwell's equations. Lumerical's STACK optical solver provides a set of script-based functions (stackdipole, stackpurcell) for this purpose. Additionally, the STACK simulation object in FDTD provides a GUI for the script commands.
STACK for plane wave illumination
The stackrt script command returns the reflection and transmission of a plane wave through an arbitrary multilayer stack using the analytic transfer matrix method. This function returns the fraction of transmitted and reflected power (Ts, Tp, Rs, Rp), and the complex reflection and transmission coefficients (ts, tp, rs, rp), for both S and P polarizations. The stackfield script command returns the field information (Es, Ep, Hs, Hp) for the stack.
For both stackrt and stackfield, the user must specify the angle of incidence and frequency range of the illumination, as well as the thickness and refractive index of each layer. For a comparison between results obtained using the analytic transfer matrix method and 1D FDTD simulations, please see 4 layer stack application example.
STACK for diople emission
For many thin-film applications such as OLEDs and other electroluminescent devices, both the quantum efficiency and extraction efficiency are affected by the interference between layers. The stackdipole and stackpurcell script commands are ideal for studying this microcavity effect as it analytically calculates the emission characteristics of a dipole source (or dipole sources) based on its location in the stack.
The stackdipole function returns the luminance (cd/m^2) and radiance (W/steradian/m^2) as a function of emission angle, as well as the corresponding X, Y, Z tristimulus values. The CIE 1931 color functions are used for calculating X, Y, Z. To determine how the stack geometry affects the quantum efficiency and extraction efficiency separately, the stackpurcell can be used.
Please note that stackdipole and stackpurcell requires a separate license in addition to a standard FDTD license.
- K. A. Neyts, "Simulation of light emission from thin-film microcavities", J. Opt. Soc. Am. A, Vol. 15, No. 4 (1998)
- W. Lukosz and R. E. Kunz, "Light emission by magnetic and electric dipoles close to a plane interface", J. Opt. Soc. Am. 67, 1607-1619 (1977)
- CIE Proceedings (1932), 1931. Cambridge: Cambridge University Press.
See Video: Optimize Your OLED/LED in One Second for examples on how to use the Stack optical sovler to simulate OLEDs and LEDs.
See stackdipole for an example of a multilayer stack dipole emission calculation.