Date of Award

2017

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Electrical Engineering (MS)

Administrative Home Department

Department of Electrical and Computer Engineering

Advisor 1

Christopher Middlebrook

Committee Member 1

Durdu Guney

Committee Member 2

Elena Semouchkina

Committee Member 3

Miguel Levy

Abstract

Optical communication is a high speed, large bandwidth, low cost, and power efficient method of transferring data over short-haul and long-haul channels. Optical communication requires devices (optical modulators) that utilize the originating electrical signal information to modulate a corresponding optical signal. State of the art optical modulators can be used for communicating signals at modulation frequencies up to 100 GHz and faster. Polymer modulators are used over lithium niobate due to the large potential electro-optic coefficient, which has been shown to be as high as 226 pm/V in thin films.

Organic electro-optic polymers used in thin film modulators contain nonlinear optical chromophore dipoles that when aligned produce an electro-optic coefficient from the pockels effect. The magnitude of the electro-optic coefficient is dependent on the strength and uniformity of the electric field applied to the thin film polymer. In multi-layer devices the applied field is determined by design, fabrication, layer thickness, and pinhole defects that cause dielectric breakdown of the device. A laboratory process was designed and created for electro-optic contact poling of waveguide devices and thin film polymers. A sample is heated to the glass transition temperature of the electro-optic polymer and an electric field is applied to allow alignment of chromophores. The sample is then cooled to room temperature to lock the chromophores in place. Soluxra SEO100C polymer is used for validation of the poling process because of its high electro-optic coefficient potential.

First time large area contact poling of electro-optic polymer thin films is performed and verified enabling the use of electro-optic polymers in a variety of applications. The index of refraction change after poling was measured in Soluxra SEO100C spun thin films using a prism coupler to verify poling. TM index of refraction of thin film SEO100C increased by 0.00402-0.00486 with voltages of 39-51 V/μm after poling. SEO100C thin films were exposed to processing steps used during fabrication of devices for proof of concept for electro-optic poling mid-process in reduce applied voltage. The TM indexes relaxed an average of 16% back to their original values when exposed to the extra processing. A laboratory was built for electro-optic coefficient and performance calculation in multi-layer devices for future verification of poling. The half-wave voltage (Vπ) and intermodulation distortion (IMD) was shown as a proof-of-concept on a commercial Mach-Zehnder modulator.

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