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Based on theoretical modeling, we performed comprehensive investigation on the quantum and thermomechanical noise squeezing effect in nanoresonators made by two platform material systems: silicon and graphene. We discovered that quantum noise squeezing plays an important role in the effort to improve signal-to-noise ratio in graphene-based nanoresonators. The research suggests a viable strategy for implementing graphene-based nanoscale transducers with ultra-high sensitivity that can be potentially utilized to detect a variety of sensing targets, including atomic force, single biological molecule, and gravitational wave. [ABSTRACT FROM AUTHOR]

Abstract: A resonator fiber optic gyro (R-FOG) is a high accuracy inertial rotation sensor based on the Sagnac effect. Fiber ring resonator (FRR) is the core-sensing element in the R-FOG. Till now, the dynamic response of the FRR is studied, and it is found that the frequency of the resonance dip is shifted away from the resonance frequency when sweeping the laser frequency, and thus must affect the performance of the R-FOG. Therefore, dynamic characteristics analysis of the R-FOG, which usually works in the dynamic state, is in urgent need. This paper presents the expression for the dynamic demodulation curve of the R-FOG based on the triangle wave phase modulation technique. Through analysis and simulation, it is concluded that the frequency zero-deviation will be induced when the R-FOG is in dynamic state, and the gyro error caused by the frequency zero-deviation will increase as the product of the operating range and the bandwidth of the R-FOG. [Copyright &y& Elsevier]

Abstract: Crossed waveguide is widely used in optical devices, whose excess loss has a strong impact on multi-turn optical waveguide ring resonator and resonator integrated optic gyro. The resonance curve of the ring resonator is sharply dependent on the loss within the resonator. This paper presents how to get excess loss of the crossed waveguides nondestructively through the comparison of the resonance characteristics between one-turn and multi-turn optical waveguide ring resonators. [Copyright &y& Elsevier]

In this paper, how the phase modulation index’s drift affects an open-loop resonator fiber optic gyro’s (RFOG’s) performance is discussed. By using the ratio of the second to fourth harmonic (2nd/4th harmonic), a harmonic feedback technique is proposed to suppress this drift. It is found that the phase modulation index’s drift would lead to a significant measurement error, which increases with rotation rate. It is proven that there exists an approximately linear correlation between phase modulation index and 2nd/4th harmonic. Using this correlation, the 2nd/4th harmonic feedback technique is applied to the open-loop RFOG to stabilize the phase modulation index. Although the phase modulation index slightly deviates from its optimal value in the dynamic state with this technique, it is proven that the induced backscatter noise could be neglected. The test results indicate that the phase modulation index’s drift with this technique is reduced to about 22% of that without suppression technique, and the stabilities of gyro output signal are respectively improved by about 29% and 31% under 5deg/s and 10deg/s when this technique is used. It is concluded that the 2nd/4th harmonic feedback technique does work in suppressing the phase modulation index’s drift. [ABSTRACT FROM AUTHOR]

A harmonic division technique is proposed for an open-loop resonator fiber optic gyro (RFOG) to suppress semiconductor laser diode's (LD's) intensity modulation noise. The theoretical study indicates the RFOG with this technique is immune to the intensity noise. The simulation and experimental results show this technique would lead to a diminished linear region, which still could be acceptable for an RFOG applied to low rotation rate detection. The tests for the gyro output signal are carried out with/without noise suppressing methods, including the harmonic division technique and previously proposed signal compensation technique. With the harmonic division technique at the rotation rate of 10 deg/s, the stability of gyro output signal is improved from 1.07 deg/s to 0.0361 deg/s, whose noise suppressing ratio is more than 3 times as that of the signal compensation technique. And especially, a 3.12 deg/s signal jump is significantly removed with the harmonic division technique; in contrast, a residual 0.36 deg/s signal jump still exists with the signal compensation technique. It is concluded the harmonic division technique does work in intensity noise suppressing under dynamic condition, and it is superior to the signal compensation technique. [ABSTRACT FROM AUTHOR]

A miniaturized compact open-loop resonator fiber optic gyro (RFOG) prototype with main body size of about 10.4 cm×10.4 cm×5.2 cm is reported, and a demodulation signal compensation technique is proposed, aiming to suppress the drift arising from accompanying intensity modulation induced by semiconductor laser diode (LD). The scheme of how to establish this miniaturized RFOG prototype is specifically stated. The linear relationship between the first-harmonic and second-harmonic demodulated signals respectively for the two counter propagating beams in the resonator is verified by theory and experiment, and based on this relationship, the demodulation signal compensation technique by monitoring the second-harmonic demodulated signal is described in detail. With this compensation technique, the gyro output stability under 1°/s rotation rate is effectively improved from 0.12°/s to 0.03°/s, and especially, an about 0.36°/s peak-to-peak fluctuation due to tuning current reset is significantly suppressed. A long term bias stability of about 4.5°/h in 1 h for such a small-sized RFOG prototype is demonstrated, which is of the same magnitude as that of currently reported large-sized RFOG systems utilizing LD as the laser source as well. [ABSTRACT FROM AUTHOR]

Abstract: Resonator Fiber optic gyro (RFOG) is a high accuracy inertial rotation sensor based on the Sagnac effect. The optical fiber ring resonator (OFRR) is the key rotation sensing element. The backscattering characteristics of the OFRR are fully investigated. The Rayleigh backscattering dominates the backscattering spectrum with the input power below the threshold. High carrier suppression is crucial to reduce this Rayleigh backscattering error. Being different from the intrinsic Rayleigh scattering of the fiber, the stimulated Brillouin scattering (SBS) in the OFRR should be avoided. This is because the finesse and the resonance notch depth of the OFRR decrease for the pump depletion through the SBS process. The shot noise limited sensitivity (SLS) of the RFOG is improved by increasing the input power. Through analysis, it is found that the threshold input power is improved after phase modulation. The SLS of the RFOG is analyzed at different modulation parameters and its relevant SBS threshold. Accordingly, the optimized modulation frequency and the corresponding maximum input power are all obtained. A simple method of testing the frequency shift in the SBS is also proposed. In this method, the central frequency of the laser source is locked to the resonance frequency of the OFRR in one direction. A steady SBS light is observed and its frequency shift is measured together. [Copyright &y& Elsevier]

Abstract: Resonator fiber optic gyro (RFOG) is a high accuracy inertial rotation sensor based on the Sagnac effect. The digital ramp phase modulation technique is usually adopted instead of analog modulation to improve accuracy and stability. Failure to keep the stair-period of the digital ramp waveform equal to the optical transmission time in the fiber ring resonator produces errors in the RFOG. The influence of the nonideal stair period on gyro performance is firstly fully developed in this paper. The physical mechanism is an uncertain phase relationship between the transmitted light and the circulated light components in the resonator occurring in this nonideal stair-period. The effect on output signals of the resonator is fully analyzed. Through simulation, it is found that the zero position of the demodulation curve in the symmetrically digital triangle phase modulation technique is not affected by the nonideal stair-period problem. However, in the two-frequency combined digital serrodyne phase modulation technique, much effort is needed to overcome the zero-deviation, which causes errors in the RFOG. [Copyright &y& Elsevier]

Resonator fiber optic gyro (R-FOG) is a promising candidate for the next generation inertial rotation sensor whose resonant frequency is changed due to the Sagnac effect. Observed from the resonance curve, the free spectral range of the resonator, the full width at half maximum of the resonance curve, the finesse of the resonator, and the resonance depth are 35.7 MHz, 2.21 MHz, 16.2, and 0.95, respectively. In the experiment, there is an acoustic-optical modulator (AOM) in each light loop. When the frequency of the fiber laser is locked to the resonance frequency in the counterclockwise direction, the frequency difference between the driving frequencies of the two AOMs is equivalent to the frequency deviation caused by the gyro rotation. In this locked condition, the gyro dynamic range calculated from the demodulation curve in the clockwise direction is from 13.5 to −13.5 rad/s. From the signal-to-noise of the average intensity arriving in the photodiode, it can be estimated that the shot-noise-limited sensitivity of mis system will be . [Copyright &y& Elsevier]

Waveguide ring resonator (WRR) is beneficial to the miniaturization and integration of the resonant micro optic gyroscope (RMOG). The shot-noise-limited sensitivity of the RMOG equipped with the multi-turn WRR is derived. The simulation results show that when the crossing loss or the waveguide propagation loss is higher than 0.07 dB/crossing or 1.2 dB/m, the WRR of multi-turn structure does no good to the sensitivity of the RMOG. Two configurations of the WRR are introduced and tested. According to the measured waveguide propagation loss and crossing loss, the optimal angular random walk (ARW) is obtained when the RMOG equipped with a WRR of 2 or 3 turns. The ARW of the RMOG equipped with a 3-turn WRR is measured at different laser output power which agrees well with the theoretical value. • The turns of the transmission-type WRR are optimized and the optimal angular random walk (ARW) is obtained when the RMOG equipped with a WRR of 2 or 3 turns. • The ARW of the RMOG equipped with a 3-turn WRR is measured at different laser output power which agrees well with the theoretical value. [ABSTRACT FROM AUTHOR]