Discharge-induced frequency modulation of RF excited CO sub 2 waveguide lasers

Journal Article · Mon Jul 01 04:00:00 EDT 1991 · IEEE Journal of Quantum Electronics (Institute of Electrical and Electronics Engineers); (United States)

DOI:https://doi.org/10.1109/3.83396· OSTI ID:5705557

Colley, A D; Baker, H J; Hall, D R ^[1]; Abramski, K M ^[2]

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1. Heriot-Watt Univ., Edinburgh (United Kingdom). Dept. of Physics
2. Electronics Dept., Technical Univ. of Wroclaw, Wroclaw (PL)

In this paper the mechanisms causing a shift in the oscillation frequency of an RF excited CO{sub 2} 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 have been 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 {plus minus}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. However, by independent RF power modulation of a short section of the waveguide, this bandwidth has been increased to 3.5 kHz, with a sensitivity of 0.7 MHz/W and a frequency deviation of {plus minus}10 MHZ.

• OSTI ID: 5705557
• Journal Information: IEEE Journal of Quantum Electronics (Institute of Electrical and Electronics Engineers); (United States), Journal Name: IEEE Journal of Quantum Electronics (Institute of Electrical and Electronics Engineers); (United States) Vol. 27:7; ISSN 0018-9197; ISSN IEJQA
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
426002* -- Engineering-- Lasers & Masers-- (1990-)
ABSORPTION
CARBON DIOXIDE LASERS
ELECTRIC DISCHARGES
ENERGY ABSORPTION
ENERGY-LEVEL TRANSITIONS
EXCITATION
FREQUENCY MODULATION
FREQUENCY RANGE
GAS LASERS
HIGH-FREQUENCY DISCHARGES
KHZ RANGE
KHZ RANGE 100-1000
LASERS
MHZ RANGE
MHZ RANGE 01-100
MODULATION
POWER
RF SYSTEMS
SENSITIVITY
SPECTRAL SHIFT
WAVEGUIDES