Pulse selection from a mode-locked TE CO2 laser output using a resonant acousto-optic modulator

The pulse separation and associated range ambiguity of a CO 2 laser radar using a pulse burst waveform consisting of 1.3 ns mode-locked pulses spaced 40 ns apart was successfully doubled to 80 ns and 12 m respectively by suppressing every alternate pulse. This was done by sending the mode-locked laser output beam with 40 ns pulse spacing through a resonant Raman-Nath acousto-optic modulator driven at 18.75 MHz which is 1.5 times the drive frequency used to intracavity mode-lock the CO 2 laser transmitted. The spatial filtering of the diffracted pulses results in the suppression of the alternate pulses to better than 15 dB. The throughputs for the unsuppressed pulses were greater than 95%. The laser radar capability in detecting large targets,

Keywords:

• Multiphoton intrapulse interference phase scan
• Spatial filter
• Laser
• Acousto-optic modulator
• Pulse (signal processing)
• Ultrafast laser spectroscopy
• Injection seeder
• Mode-locking
• Physics
• Optics

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