Date Awarded


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)


Applied Science


William E Cooke


A colliding pulse mode-locked (CPM) laser achieves sub-picosecond operation by synchronizing two counter-propagating pulse trains to form a standing wave in a thin absorber jet. When properly aligned, these lasers maintain mode-locking for more than 100 seconds (1010 pulses), but eventually cease mode-locking for short periods of time. This thesis examines the characteristics of these transient events, when CPM mode-locking ceases (dropout) and when it resumes (dropin). The dropout is an apparently rapid event, typically lasting no longer than 5 microseconds or less than 500 pulses. The dropin takes significantly longer time, often has structure, and has a clear power dependency. This thesis uses a variety of statistical methods to search for changes in the nonlinear dynamics prior to the apparent power output change of a dropout, but does not find consistent precursors. Moreover, this thesis uses a fluence mapping method to study ultrashort pulse generation process in a novel bistable medium model. The bistable medium model naturally incorporates various high order perturbations and provides a framework for dynamics study and pulse shape control in ultrafast lasers.



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