Measurement of laser quantum frequency fluctuations using a Pound-Drever stabilization system
- Stanford Univ., CA (United States). Edward L. Ginzton Lab.
The authors describe a method for measuring the frequency fluctuation spectrum of a laser oscillator, especially the weak noise contributions in the wings of the spectrum, and apply this method to confirm the existence of large excess quantum frequency fluctuations in a laser oscillator using an unstable optical resonator. The measurement apparatus uses the Pound-Drever technique, which employs an RF phase modulator and a Fabry-Perot cavity to produce a sensitive high-speed frequency discrimination signal. The authors show that this signal can also be used to measure the quantum noise contributions to the frequency spectrum of a laser oscillator. Experimental measurements on a miniature diode-pumped Nd:YAG laser using a stable optical cavity closely match the predictions of the usual Schawlow-Townes theory, while the frequency fluctuations in a nearly identical laser employing an unstable optical resonator are approximately 1,300 times larger. These much larger fluctuations arise in part from the larger output coupling and cavity bandwidth of the unstable cavity, but they also appear to confirm a predicted excess spontaneous emission factor (Petermann excess noise factor) of [approx]180 times arising from the nonorthogonal transverse mode properties of the unstable cavity.
- OSTI ID:
- 6982249
- Journal Information:
- IEEE Journal of Quantum Electronics (Institute of Electrical and Electronics Engineers); (United States), Vol. 30:6; ISSN 0018-9197
- Country of Publication:
- United States
- Language:
- English
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