Temperature Dependence of Holographic Filters in Phenanthrenquinone-Doped Poly(Methyl Methacrylate)

Abstract

A variety of holographic filters formed in phenanthrenquinone-doped poly(methyl methacrylate) (PQ/PMMA) for use as passive filters in DWDM and OCDMA have been demonstrated. Low cost PQ/PMMA filters can be fabricated with narrow spectral transmittance (<0.2nm) and high side-lobe suppression (-30dB) properties in the 1550nm wavelength range. However, the thermal stability of filters formed in PQ/PMMA must be understood in order to use them in optical communication systems. In addition, an understanding of the thermal dependence of PQ/PMMA filters can provide a path to tunable devices that can significantly increase the flexibility of multiplexing systems allowing dynamic functions such as active routing for switched network topologies. This thesis investigates the temperature dependence of edge-illuminated holographic filters formed in phenanthrenquinone-doped poly(methyl methacrylate) (PQ/PMMA) operating at 1550nm. The fabrication and recording processes and the operation principles of the filters are detailed. The thermally induced change to the refractive index and volume can be used to select the wavelength filtered by the grating. The temperature can be varied over a range of 15°C without introducing noticeable hysteresis effects. The wavelength can be tuned at a rate of 0.03nm/°C over this temperature range. A model for the temperature tuning effect is presented and compared to experimental results. A procedure to incorporate silicon dioxide nanoparticles as secondary doping agent is also described. The effect of the secondary dopant on the operation and thermal properties of the filters is presented with experimental results and models.