Collision broadening and quantum noise in a very large laser gyroscope

Wyss, Christian; Wright, D.N.; King, B.; McLeod, D. P.; Cooper, Steven J.; Stedman, Geoffrey

doi:10.1016/s0030-4018(99)00655-0

Cited by 6 publications

(1 citation statement)

References 17 publications

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“…Dithering noise [11] is the main component of the random walk in the dithered RLGs; therefore, reducing their random walk with increasing power is rarely effective [12] . As for nondithered RLGs, such as ultralarge RLGs and differential RLGs (DILAG for short), the random walk decreases with increasing power according to the P −1/2 rule [7,9] . We measured the random walk as a function of laser power for three DILAGs; however, the results showed enormous departure from the P −1/2 rule.…”

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confidence: 99%

Quantum limit in low-loss ring laser gyros

2012

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Contrary to expectations, a measurement of the random walk in the ring laser gyro (RLG) as a function of laser power P shows that it is not consistent with the P −1/2 rule. In the experiment, the random walk and laser power are tested and recorded at different discharge currents. The random walk decreases with increasing power, but with a rate much less than the theoretical value according to current literature. In order to solve the inconsistency above, we derive the expression for the random walk in RLGs based on laser theory. Theoretical analysis shows that, accumulating effects of lower energy level due to its limited lifetime lead to additional quantum noise from spontaneous emission. Results show that the random walk in the RLGs consists of two components. The former decreases with increasing power according to the P −1/2 rule, whereas the other is power-independent. Thus far, the power-independent quantum limit has not appeared in the literature; therefore, the expressions for RLGs should be modified to describe the lowloss RLGs exactly, where the power-independent term takes a relatively larger proportion. The findings are significant to the further reduction of quantum limit in low-loss RLGs.OCIS Ring laser gyros (RLGs) have been widely used in areas such as inertial technology, fundamental physics, and geophysics for their abilities to accurately measure angular rates with frequency difference between counter traveling wave modes [1−3] . In some applications, the random walk gives a limit to the RLG system, e.g., RLG rotating inertial navigation system [4] , telescope pointing and tracking system [5] , and ultralarge RLGs [6−8] . The ultimate limit to the random walk in RLGs is determined by quantum noise, which is also called the quantum limit [9,10] . The quantum limit is usually considered proportional to P −1/2 in classical literature on RLGs, where P is laser power [9,10] . Dithering noise [11] is the main component of the random walk in the dithered RLGs; therefore, reducing their random walk with increasing power is rarely effective [12] . As for nondithered RLGs, such as ultralarge RLGs and differential RLGs (DILAG for short), the random walk decreases with increasing power according to the P −1/2 rule [7,9] . We measured the random walk as a function of laser power for three DILAGs; however, the results showed enormous departure from the P −1/2 rule. In order to explain the inconsistency between the experimental results and theory in current literature, we analyzed the experimental phenomena based on laser theory. Results show that the quantum limit in the low-loss RLGs is not proportional to P −1/2 . Therefore, expressions for quantum limit in the RLGs should be modified.

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confidence: 99%