Laser-frequency multiplication

Technical Report · Fri Nov 01 00:00:00 EST 1991

OSTI ID:5615746

A high quality mode locked pulse train was obtained at 9.55 micrometers, the CO2 wavelength chosen for frequency doubling into the atmospheric window at 4.8 micrometers. The pulse train consists of a 3 micro sec burst of 1.5 nsec pulses separated by 40 nsec, in a TEM(00) mode and with a total energy of 100 mJ. The pulse intensity without focussing is about 3 MW/sq.cm., already quite close to the target intensity of 10 MW/sq.cm. for frequency doubling in a AgGaSe2 crystal. The mode-locked train is obtained by intracavity modulation at 12.5 MHz using a germanium crystal driven with a power of about 30 Watts. Line selection is achieved firstly by the use of a 0.92 mm thick CaF2 plate at the Brewster angle within the cavity, which completely suppresses 10.6 micrometer band radiation. Secondly, a particular rotational line, the P20 at 9.55 micrometers, is selected by the injection of a continuous beam is mode-matched to the pulsed laser cavity using a long focal length lens, and for best line-locking it is necessary to fine tune the length of the pulsed laser resonator. Injection causes substantial depression of the gain switched spike.

• Research Organization: Textron, Inc., Everett, MA (United States). Textron Defense Systems
• OSTI ID: 5615746
• Report Number(s): AD-A-243864/6/XAB; CNN: N00014-91-C-2279
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
CARBON DIOXIDE LASERS
MODE LOCKING
CRYSTALS
FREQUENCY MODULATION
GAIN
GERMANIUM
HARMONIC GENERATION
LASER CAVITIES
LENGTH
LENSES
PULSES
RESONATORS
ROTATION
TARGETS
AMPLIFICATION
DIMENSIONS
ELECTRONIC EQUIPMENT
ELEMENTS
EQUIPMENT
FREQUENCY MIXING
GAS LASERS
LASERS
METALS
MODULATION
MOTION
426002* - Engineering- Lasers & Masers- (1990-)