Active resonators based on optical waveguides can significantly enhance the performance of optical gyroscope due to its loss compensation effect. The spontaneous emission noise (SEN) stemmed from optical gain will broaden the linewidth of the resonator and limit the sensitivity and resolution of active resonator optical gyroscope (AROG). In this paper, we modified the sensitivity formula when the spontaneous emission noise is dominant and analyzed theoretically the performance limitations of the AROG. After considering the spontaneous emission noise source, the resolution can be improved through optimizing the design parameters of the AROG
40P<sub>2</sub>O<sub>5</sub>-20Al<sub>2</sub>O<sub>3</sub>-(30-x)Na<sub>2</sub>O-10BaO-xEr<sub>2</sub>O<sub>3</sub> (PANB) glasses with different Er<sup>3+</sup> concentrations were fabricated by the traditional melt quenching method and their spectroscopic properties were investigated. Glass thermal stability is investigated by differential scanning calorimetry (DSC) (T<sub>x</sub>-T<sub>g</sub>=138°C) which indicates a better recrystallization performance than that of fluorophosphates glass and fluorotellurite glass. The derived Judd-Ofelt intensity parameters of Er<sup>3+</sup> doped PANB glass (Ω<sub>2</sub>=18.8, Ω<sub>4</sub>=15.9, Ω<sub>6</sub>=5.38(×10<sup>-20</sup>cm<sup>2</sup> )) indicate higher asymmetry and stronger covalent environment when compared with Er<sup>3+</sup> doped tellurite, fluoride and fluorotellurite glasses. Compared with Er<sup>3+</sup> transitions in other glass hosts, large stimulated emission cross-section and broad full wave at half maximum (FWHM) were found to be 4.58×10<sup>-20</sup>cm<sup>2</sup> and 60 nm centered at ∼1550 nm, respectively. It implies a potential material for infrared lasers and amplifiers.
The Risley-prism system is applied in imaging LADAR to achieve precision directing of laser beams. The image quality of LADAR is affected deeply by the laser beam steering quality of Risley prisms. The ray-tracing method was used to predict the pointing error. The beam steering uncertainty of Risley prisms was investigated through Monte Carlo simulation under the effects of rotation axis jitter and prism rotation error. Case examples were given to elucidate the probability distribution of pointing error. Furthermore, the effect of scan pattern on the beam steering uncertainty was also studied. It is found that the demand for the bearing rotational accuracy of the second prism is much more stringent than that of the first prism. Under the effect of rotation axis jitter, the pointing uncertainty in the field of regard is related to the altitude angle of the emerging beam, but it has no relationship with the azimuth angle. The beam steering uncertainty will be affected by the original phase if the scan pattern is a circle. The proposed method can be used to estimate the beam steering uncertainty of Risley prisms, and the conclusions will be helpful in the design and manufacture of this system.
We theoretically analyze the characteristics of scale factor in frequency sensitive integrated optical gyroscope consisting of a ring resonator coupled with double ring resonators. The impact of through coupling coefficients is investigated to decide the optimal parameters located at 0s<sup>-1</sup> for improving the scale factor. It demonstrates that the scale factor enhancement in this frequency sensitive optical gyroscope, without increasing the overall footprint, can be improved compared with conventional single ring resonator gyroscope and presents the characteristic of better performance within low-rate range. It implies a broad prospect in highly integrated on-chip applications, especially in aeronautic and astronautic area.
In this paper, an active ring-coupled Mach-Zehnder interferometer (arcMZI) for rotation sensing is proposed. Theoretical resolution formula of this arcMZI gyroscope was deduced by using of transfer matrix method and noise analysis model. The simulation result shows that the theoretical maximum sensitivity of arcMZI gyroscope can be enhanced at least two orders of magnitude compared with the single-bus resonator (SBR) gyroscope for the same footprint and effective loss after equivalent optimization. The arcMZI gyroscope could be of great potential to meet the tactical demands of future inertial navigation.
Optical waveguide is used in most integrated optic devices to confine and guide light in higher refractive index channels. The structures and materials of slot waveguides are reviewed in this paper. Coupled resonator optical waveguides (CROWs) can be used for a rotation sensor with compact size, low power consumption and low cost. The loss determines the ultimate sensitivity of CROW gyros. Resonator-based optical gyroscope’s sensitivity for measuring rotation is enhanced via using the anomalous dispersion characteristic of superluminal light propagation, which can be also generated by using passive optical resonators.
We propose and analyze a gyroscope using active three-dimensional vertically coupled resonators (3D-VCRs), which allows for loss compensation, unidirectional propagation, and a larger sensing area while maintaining the same bulk volume. For the ideal uniform case, the minimum detectable rotation rate ΔΩmin of the active 3D-VCR gyroscope can be decreased by above three orders of magnitude after optimization compared with the passive case. The minimal measurable rotation rates of the 3D-VCR gyroscope, the loss-compensated coupled resonator optical waveguide (LC-CROW) gyroscope, and the equivalent resonant waveguide optical gyroscope (RWOG) decrease with a higher number N of the resonators. Finally, it is shown that the uniform active 3D-VCR gyroscope has a better resolution ΔΩmin than the equivalent LC-CROW and RWOG.
Active coupled resonator optical waveguide (CROW) structure can significantly enhance the performance of optical gyroscope due to its loss compensation effect and highly dispersive properties. In this paper, we analyze the effect of optical gain and its induced noise, i.e. spontaneous emission noise, on the properties of the active CROWs. A thorough investigation of the impact of various disorder degrees on the performance of the active three dimensional vertically coupled resonators (3D-VCR) gyroscope has been performed. It shows how the disorder interacted with coupling coefficient affects the achievable resolution ΔΩ<sub>min</sub> of gyroscope, and the degree of disorder will supplant the propagation loss to become an ultimate limitation. Finally, it is shown that the active 3D-VCR gyroscope (the number of ring, N>6) has better resolution ΔΩ<sub>min</sub> than that of the equivalent resonant waveguide optical gyroscope (RWOG).
A control system designed for a Double-Prism scanner is discussed in this paper. This control system is required to
regulate the speed of prisms accurately and change the scan pattern as quickly as possible. Therefore, we designed a
digital double closed-loop control system which consists of an inner loop and an outer loop to achieve that function. In
this double closed-loop control system, the inner loop uses linear Proportional-Integral (PI) controller for the current
control and the outer loop uses saturated Proportional-Integral controller for the speed control. To verify the feasibility
and rationality of this control method, simulation based on MATLAB was performed. And the simulation results indicate
that the step response of prism speed is stable and there is no steady state error. After building the digital control system,
many experiments were performed to obtain key characteristics. The experiment results show that the speed regulation
time is about 0.4s when the reference speed is 1rps. The accuracy of speed regulation reaches 10<sup>-4</sup> level, and the
fluctuation ratio of speed regulation reaches 10<sup>-2 </sup>level over its operation range(0rps-3rps).
We propose a configuration consisting of several passive ring resonators named as fast-light
enhanced ring resonator, coupled to an active ring laser for introducing anomalous dispersion.
Theoretical analysis indicates that the introduced anomalous dispersion allows the frequency shift to
be improved as large as one order of magnitude due to Sagnac effect when the structure is rotated,
namely having the same rotational sensitivity compared to a standard ring-laser gyroscope (RLG)
with tenfold size as that of the proposed structure. In this paper, the impact of passive ring resonator
number is discussed and deduced, which manifests that only odd number of passive rings will
produce effective anomalous dispersion, thus improve the rotational sensitivity. The configuration
proposed here will have broad prospect in realizing highly integrated on-chip laser gyroscope for