Phase Change Materials for Optoelectronic Devices and Memories :

Date of Award


Degree Name

Ph.D. in Electro-Optics and Photonics


Department of Electro-Optics and Photonics


Imad Agha


Photonics is really the study of the manipulation of light. In order to manipulate light, the materials the light is propagating through need to be understood. One very important group of materials used for the manipulation of light are what are known as phase change materials (PCMs) and in particular chalcogenide PCMs. Chalcogenide materials are materials that include at least one element from the VIth row of the periodic table. These materials are so important because of their amazing ability to switch between material states in either a volatile or non-volatile fashion. Each of these different states has very different optical, electrical, and or thermal properties. By learning how to manipulate these materials we can create all types of photonic devices such as, spatial light modulators, accumulator memories, optical computing circuits, variable resistors, and even passive temperature control windows. This work covers various experimental setups, measurement techniques, and devices for the characterization and implementation of these fascinating materials, in particular Ge2Sb2Te5 or GST which has been known about for over 50 years, but is still not completely understood. Utilizing the power of electro-optic modulators I have created an original setup that has full control over the number of pulses as well as pulse shape for 1550 nm and 775 nm light. A pump-probe measurement scheme was implemented to achieve in situ reflection measurements before, during, and after a phase change event. An interferometer was employed to add phase accumulation measurements to the setup's capabilities as well. All this information is vital for the understanding of these materials.


Optics, Phase Change Materials, PCMs, Photonics, GST, SLM, Spatial Light Modulator, Photonic Devices

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