Characterization of electrical noise limits in ultra-stable laser systems

Zhang, Jie; Shi, Xiaohui; Zeng, Xiangbin; Lü, Xiaolong; Deng, Ke; Lu, Zehuang

doi:10.1063/1.4971852

Cited by 16 publications

(17 citation statements)

References 35 publications

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“…1, two ultrastable laser systems (USL Sys1 and USL Sys2) are used here, which are described in detail in Ref. [18]- [19]. These two ultrastable laser systems are thermal noise limited at a level of 1×10 −15 and the beat note frequency fluctuation is less than 1 Hz with a 1 s gate time, so the stability level is sufficient for the current experiment.…”

Section: Resultsmentioning

confidence: 99%

Suppression of residual amplitude modulation effects in Pound–Drever–Hall locking

et al. 2018

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Residual amplitude modulation (RAM) effects in a Pound-Drever-Hall (PDH) technique locked cavity system is analyzed in this paper. The suppression of the amplitude of the RAM has been investigated by many groups, while the effect of the cavity response has not received full attention. Frequency shift caused by RAM in the PDH method is found to be both related to the amplitude of the RAM effects and to the cavity's mode matching and impedance matching. According to our analysis, RAM effects can be fully suppressed by choosing proper impedance matching parameter and magic mode coupling efficiency. We measure the RAM-to-frequency conversion coefficients at different coupling efficiencies. The result agrees well with our theoretical model, demonstrating the potential of full suppression of the RAM effects through proper design of cavities.

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Section: Resultsmentioning

confidence: 99%

Suppression of residual amplitude modulation effects in Pound–Drever–Hall locking

et al. 2018

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“…From the perspective of control theory, a typical block diagram of the feedback control loop in a laser frequency stabilization system was given by T. Day et al and shown in Figure 2 [ 29 , 30 ]. We denote the noise contribution of the laser source as

, the noise contribution of the frequency discrimination system as

, and the noise contribution of the servo feedback system as

.…”

Section: Control Modelmentioning

confidence: 99%

“…The conversion factor of the actuator is denoted as K in units of

. In the closed-loop condition, the total closed-loop frequency noise power spectral density can be expressed as [ 29 , 30 ]:

where the units of

are

. It can be seen from Equation ( 2 ) that the closed-loop frequency noise depends on the open-loop gain of the system.…”

Section: Control Modelmentioning

confidence: 99%

“…The frequency discrimination slope

is the coefficient that converts the frequency detuning between the laser and the cavity resonant peak into voltage. Actually,

has a dependence on frequency

and can be given by [ 30 ]:

where

is the linewidth of the ring cavity and

is the flat response coefficient within the cavity linewidth. We can obtain the cavity linewidth through a cavity ring-down time measurement.…”

Section: Noise Analysismentioning

confidence: 99%

“…The amplitude noise of the laser in this frequency band can be ignored, and we should take the shot-noise into account first. In the experiment, the incident light power

is 110.0 µW, and the calculated shot-noise contribution

is about

, taking into account the conversion loss of the frequency mixer

and the PD responsivity R [ 30 ]. Using the discrimination slope parameter, the shot-noise contribution to the rotation sensitivity is

, which is the shot-noise limit of our PRG and is shown with the red dashed line in Figure 6 .…”

Section: Noise Analysismentioning

confidence: 99%

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Noise Analysis of a Passive Resonant Laser Gyroscope

Liu

Zhang

et al. 2020

Sensors

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Large-scale laser gyroscopes have found important applications in Earth sciences due to their self-sufficient property of measurement of the Earth’s rotation without any external references. In order to extend the relative rotation measurement accuracy to a better level so that it can be used for the determination of the Earth orientation parameters (EOP), we investigate the limitations in a passive resonant laser gyroscope (PRG) developed at Huazhong University of Science and Technology (HUST) to pave the way for future development. We identify the noise sources from the derived noise transfer function of the PRG. In the frequency range below 10−2Hz, the contribution of free-spectral-range (FSR) variation is the dominant limitation, which comes from the drift of the ring cavity length. In the 10−2 to 103Hz frequency range, the limitation is due to the noises of the frequency discrimination system, which mainly comes from the residual amplitude modulation (RAM) in the frequency range below 2 Hz. In addition, the noise contributed by the Mach–Zehnder-type beam combiner is also noticeable in the 0.01 to 2 Hz frequency range. Finally, possible schemes for future improvement are also discussed.

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Long-term digital frequency-stabilized laser source for large-scale passive laser gyroscopes

Zhang

Liu

et al. 2020

Review of Scientific Instruments

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We report on the development of a digitally controlled long-term frequency stabilized ultrastable laser source, which serves as an injection laser to stabilize the perimeter of a 3 m × 3 m heterolithic passive resonant gyroscope. We operate the gyroscope at two different cavity modes to reduce back-scattering coupling disturbance for gyroscope locking. This scheme increases the requirement for the injection laser frequency stability since we are using the wavelength of the laser as the length standard for the heterolithic gyroscope structure. The laser source is digitally locked to an ultrastable high-finesse Fabry-Perot cavity and a femtosecond optical frequency comb referenced to an active hydrogen maser simultaneously. The fractional frequency stability of the locked laser is better than 1.2 × 10−14 for averaging times from 0.1 s to 10 000 s. The short-term frequency stability is limited by the stability of the Fabry-Perot cavity, and the long-term frequency stability is limited by the stability of the frequency comb. The digital locking system enables the laser to run autonomously for weeks and can quickly relock itself within seconds to ensure continuous running of the gyroscope. The digital frequency stabilization technique can also fulfill the requirements of space gravitational waves detection and the next generation space gravity recovery mission.

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Characterization of electrical noise limits in ultra-stable laser systems

Cited by 16 publications

References 35 publications

Suppression of residual amplitude modulation effects in Pound–Drever–Hall locking

Suppression of residual amplitude modulation effects in Pound–Drever–Hall locking

Noise Analysis of a Passive Resonant Laser Gyroscope

Long-term digital frequency-stabilized laser source for large-scale passive laser gyroscopes

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