Title :
Discharge-induced frequency modulation of RF excited CO2 waveguide lasers
Author :
Colley, Alan D. ; Abramski, Krzysztof M. ; Baker, Howard J. ; Hall, Denis R.
Author_Institution :
Dept. of Phys., Heriot-Watt Univ., Edinburgh, UK
fDate :
7/1/1991 12:00:00 AM
Abstract :
The mechanisms causing a shift in the oscillation frequency of an RF-excited CO2 waveguide laser through changes in the discharge excitation power are investigated. Frequency shifts in the range of ±0.5 to 1 MHz per watt of RF input power were measured. These are shown to be consistent with the effects of thermal expansion of the laser gas caused by an increase of the gas temperature due to RF power absorption. It is also shown that the effects of gas dissociation are small but significant, whereas, contrary to earlier suggestions, the effects of electron density fluctuations are negligible. The discharge-induced frequency shift may be used as a simple frequency modulator with a frequency deviation of ±30 MHz, although the usefulness of this effect is limited to a bandwidth of about 500 Hz, due to the acoustic resonance of the waveguide channel
Keywords :
carbon compounds; gas lasers; optical modulation; optical waveguides; RF input power; RF power absorption; acoustic resonance; bandwidth; discharge excitation power; discharge induced frequency modulation; discharge-induced frequency shift; electron density fluctuations; frequency deviation; gas dissociation; gas temperature; laser gas; mechanisms; oscillation frequency; radiofrequency excited CO2 waveguide lasers; simple frequency modulator; thermal expansion; waveguide channel; Frequency measurement; Frequency modulation; Gas lasers; Laser excitation; Laser transitions; Power lasers; Power measurement; Radio frequency; Waveguide lasers; Waveguide transitions;
Journal_Title :
Quantum Electronics, IEEE Journal of
