Servo Stabilization of Two CO2 Lasers 10.7 MHz Apart.
Final rept. Jan-Oct 74
SYSTEMS RESEARCH LABS INC DAYTON OHIO
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Two carbon dioxide lasers were stabilized relative to each other by negative feedback, when the two optical cavities were mounted in a common mechanical cavity. With negative feedback, the lasers maintained a relative frequency stability one order of magnitude better than the no feedback, free-running, condition. The feedback system consisted of a HgCdTe detector operating in the photovoltaic mode to provide the beat frequency signal of the two lasers it included also an inexpensive IC discriminator circuit operating at the FM intermediate frequency of 10.7 MHz, and the appropriate amplification to drive the piezoelectric length control of one laser, and thus modify the absolute frequency of that laser. When the absolute frequencies of the lasers were inverted relative to the negative feedback situation, the feedback system produced positive feedback. With positive feedback, the lasers maintained a frequency stability, relative to each other, of one order of magnitude worse than the no feedback, free-running condition.
- Lasers and Masers