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Updated: Apr 21, 2026

Fabrication and Testing of Microfluidic Optomechanical Oscillators
Published on: May 29, 2014
Theory of self-oscillation and mode locking in a longitudinal photoacoustic resonator
Ziyao Tang1, Han Jung Park1, Roger M Diebold2
1Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
Abstract:
The wave equation for pressure that governs generation of the photoacoustic effect possesses a forcing term proportional to the time derivative of the energy delivered to the gas per unit volume and time. A positive pressure fluctuation, with its accompanying density increase, thus increases the optical absorption and provides a positive feedback mechanism for sound generation. A theory for self-oscillation in a one-dimensional resonator is given. Expressions for the photoacoustic pressure are derived for the cases of highly and weakly absorbing gases that indicate mode-locked sound generation. Experiments with CO2 lasers are reported where evidence of the self-generation effect was sought.
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