Construction and measurement of an actively mode-locked sigma laser
Butler, James M.
Pace, Phillip E.
Powers, John P.
MetadataShow full item record
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
RightsThis publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
NPS Report NumberNPS-EC-98-011
Showing items related by title, author, creator and subject.
Bewley, Scott A. (Monterey, California. Naval Postgraduate School, 1998-12-01);The ability to directly oversample and digitize microwave range signals at an antenna is not possible with current electronic technologies. The objective for this thesis was to design and computer model an optical sampling ...
Pace, Phillip E.; Powers, John P. (Monterey, California. Naval Postgraduate School, 1998-03-16); NPS-EC-98-009Optical sampling of wideband microwave signals has recently gained a lot of attention due to the availability of high repetition rate mode-locked lasers. This report examines the state-of-the-art in mode-locked lasers and ...
Anderson, James A. (Monterey, California. Naval Postgraduate School, 2000-06);Electro-optic techniques for analog-to-digital conversion (ADC) are being developed for wideband signal collection and analysis. They have the capability of being used for direct signal reception and ADC at an antenna. A ...