Kråkenes K, Bløtekjaer K
Opt Lett. 1989 Oct 15;14(20):1152-4. doi: 10.1364/ol.14.001152.
The use of a Sagnac interferometer as an acoustic sensor is discussed. Compared with a Mach-Zehnder interferometer it has the advantage of zero path-length difference. The sensitivity for low frequencies is shown to be proportional to frequency. With a passive homodyne-detection scheme using a 3 x 3 directional coupler, we report a noise-equivalent phase shift of 2.5 x 10(-7) rad/ radicalHz at 10 kHz. The detectivity is believed to be limited by backscattered light.
讨论了将萨格纳克干涉仪用作声学传感器的情况。与马赫-曾德尔干涉仪相比，它具有光程差为零的优势。结果表明，其对低频的灵敏度与频率成正比。通过使用3×3定向耦合器的无源零差检测方案，我们报告在10 kHz时的等效噪声相移为2.5×10⁻⁷ rad/√Hz。据信，探测率受背向散射光的限制。
