Construction and measurement of an actively mode-locked sigma laser
By: James M. Butler
Publisher: Naval Postgraduate School; Available from National Technical Information Service
Published: 1998
Place of publication: Monterey, Calif; Springfield, Va
Language: eng
Number of pages: 150
Other titles: NPS-EC-98-011.
Description: The direct digitization of microwave signals of interest would allow rapid computer processing and analysis.      Current analog-to-digital converters (ADCs) are bandwidth limited and electronic warfare systems must      down-convert the signal before digitization causing a loss of information. Optical ADCs can directly digitize      frequencies greater than 10 GHz using wideband integrated optical interferometers (folding ADCs). A critical      component of the optical folding ADC is the pulsed laser used for sampling the wideband signal. The      amplitude-modulated pulses become the discrete samples of the analog signal. Limiting factors in an optical      ADC are the pulsewidth, the pulse rate, and the jitter noise of the optical pulse train. Mode-locked lasers      provide pulse rates and pulsewidths suitable for high bandwidth applications. In this thesis a mode- locked      sigma laser was constructed using fiber-optic, electro-optic, and microwave components. The theory of      mode-locking, laser construction, output measurements, and sampling applications are discussed in detail. The      mode-locked sigma laser demonstrated a pulse repetition frequency of 16 6Hz, pulsewidth of 7.2 picoseconds,      amplitude noise less than 1%, temporal jitter of 386 femtoseconds, and the ability to be harmonically      mode-locked at twice the modulation frequency using only 200 mW of diode pump power in the optical      amplifier. The analysis shows that this laser can be used in an optical ADC to sample a 6.44 GHz signal at 7      bits, 3.22 GHz at 8 bits, or 1.61 GHz at 9 bits of resolution.
Notes: Thesis advisor(s): Phillip E. Pace, John P. Powers.

"NPS-EC-98-011."

"June 1998."

Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, June 1998.

Includes bibliographical references (p. 143-148)

Approved for public release; distribution unlimited.

Also available online.

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US Navy (USN) author.

dk/dk cc:9116 9/18/98.