
Martina
Gerken and David A. B. Miller, "Limits to the performance of dispersive
thinfilm stacks," Applied Optics 44, No. 18, 3349 – 3357 (2005)
Dispersive thinfilm stacks
are interesting as compact, costeffective devices for temporal
dispersion compensation and wavelength multiplexing. Their performance
depends on the total group delay or spatial shift that can be achieved.
For general multilayer stacks no analytic model exists relating the
performance to the stack parameters such as the refractive indices and
the number of layers. Here we develop an empirical model by designing
and analyzing 623 thinfilm stacks with constant dispersion. From this
analysis we conclude that for given stack parameters the maximum
constant dispersion value is inversely proportional to the wavelength
range over which the dispersion is achieved. This is equivalent to
saying that, for constant dispersion, there is a maximum possible
spatial shift (or group delay) that can be achieved for a given material
system and number of layers. This empirical model is useful for judging
the feasibility of dispersive photonic nanostructures and photonic
crystal superprism devices and serves as a first step in the search for
an analytic performance model. We predict that an 8channel wavelength
multiplexer can be realized with a single 21mm
thick SiO_{2}Ta_{2}O_{5} thinfilm
stack.
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