University of Connecticut

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PhD Dissertation Defense

Tuesday, June 28, 2022
2:00pm – 4:00pm

Storrs Campus

Graduate Student Bradley Clarke, Department of Physics, University of Connecticut

Development of an Amplified Chirp System and its Application to Ultracold Molecules

We have developed a system for producing amplified pulses of frequency-chirped light at 780 nm on nanosecond timescales for use in ultracold 87Rb photoassociation (PA) experiments. The system starts with tunable cw laser light and employs a pair of fiber-based phase modulators, a semiconductor optical amplifier, and a tapered amplifier to generate arbitrary optical frequency chirps with peak powers greater than 1 W. Driving the modulators with an arbitrary waveform generator enables arbitrary chirp shapes, such as one/two-frequency linear chirps, which enhance the rate of PA molecule formation compared to unchirped light. We overcome the optical power limitations of the modulators by duty cycling and avoid unseeded operation of the tapered amplifier by multiplexing the chirped pulses with “dummy” light from a separate diode laser. Despite amplified spontaneous emission (ASE) making up only 3% of the amplified chirp system's output, its presence can be a considerable hindrance to PA experiments. However, advantageous use of ASE has helped to illuminate the mechanisms for 87Rb magneto-optical-trap formed ultracold molecules.

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Prof. P. Gould

Physics Department (primary), College of Liberal Arts and Sciences, UConn Master Calendar

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