Coupled Resonator Optical Waveguide Gyroscope Research Articles

Analysis of coupled resonator optical waveguide gyroscope based on periodically modulated coupling and circumferences

Based on periodically modulated coupling and circumferences, we developed a new structure for coupled resonator optical waveguide (CROW) gyroscopes. Its sensitivity and resolution were significantly improved. With our new structure, which overcomes the individual limitations of the previous schemes, the sensitivity and resolution of our gyroscope are higher than those with coupling-coefficient modulation alone and circumference modulation alone. The resolution of the gyroscope gradually declines with increasing resonator propagation loss; when the quality factor Q≤2×106, the height of the center resonance peak of the transmission band decreases by more than 90%. Fortunately, this effect can be weakened by increasing the circumference difference. We also numerically analyzed the influence of manufacturing errors on the performance of the gyroscope. We found that the fluctuations of radius have a greater influence than the fluctuations of quality factor.

Sensitivity limit of a coupled-resonator optical waveguide gyroscope with separate input/output coupling

This paper studies a coupled-resonator optical waveguide (CROW) gyroscope consisting of identical coupled rings and coupling ratios except the input and output couplers have a different coupling ratio. Under certain circumstances this gyroscope is found to be more sensitive than the same gyroscope with all equal coupling ratios. However, its maximum achievable sensitivity does not exceed that of an optimized single-ring resonator gyroscope with the same ring radius and loss. This conclusion applies whether the CROW gyroscope is folded or unfolded, whether it utilizes one or two input/output waveguides, and regardless of the number of rings and waveguide loss.

Design and optimization of integrated micro optical gyroscope based on a planar ring resonator

In order to optimize the performance of the coupled resonator optical waveguide (CROW) gyroscope, a well-designed structure by optimizing the ring number and the transmission coefficient of the coupler is used as the core component of the planar waveguide optical gyroscope. The structure with double coupled ring resonator may possess large effective group refractive index to enhance angular sensing sensitivity was proposed. The concept of the Sagnac effect in this new double coupled ring resonator structure with a large effective group refractive index is investigated, it’s found that the rotation-induced phase shift is proportional to the effective group refractive index. On the basis of this effect, we calculate the general relation expression of theoretical rotation sensitivity and the effective group refractive index for this two-ring bidirectional CROW gyroscope by numerically simulation. Based on the relation, the phase shift characteristics of double coupled ring resonator and single ring resonator was analyzed. And the changing characteristics of the transmission coefficient of the couplers and the effective group refractive index was discussed based on the double cascaded ring resonator coupling mode theory. In the case of R1=R2=100 μm and ring transmission loss coefficient t1=t2=0.95, the generating condition of the largest effective group refractive index was obtained, according to the different effects of the couplers between rings and waveguide on the effective group refractive index. By using the parameters of R=100 μm and t=0.95, the sensitivity of a single ring resonator gyroscope is (104-105) °/h, and the sensitivity of double coupled ring resonator gyroscope can reach to 10 °/h. In summary, we show that the theoretical sensitivity of the double coupled ring gyroscope and single ring gyroscope are comparable when both have the same parameters. Using numerical and analytical methods, we demonstrated that coupling multiple resonators together can enhance rotation sensitivity. This research is important for applications of coupled ring resonator in optical angular velocity detection, and a promising regime to realize highly compact optical gyroscope.

Effect of Static Disorder on Sensitivity of Coupled Resonator Optical Waveguide Gyroscopes

Coupled resonator optical waveguides (CROWs) have shown theoretical promise as microoptical integrated gyroscopes with sensitivities exceeding comparably sized MEMS gyroscopes. Here, we analyze the effect of static disorder on the rotational sensitivity of a CROW gyroscope. Since CROWs consist of a one-dimensional array of evanescently coupled ring-shaped microresonators, disorder includes random variations of the resonator optical path length and couplings between them resulting from manufacturing errors. We show that the rotational sensitivity of the CROW gyro is relatively stable with respect to variations in the interresonator coupling. By contrast, even modest fluctuations in the resonators' roundtrip optical path length result in substantially lower rotational sensitives. Finally, it is shown that while most random configurations of defects reduce the maximum sensitivity, there are particular configurations for which the rotation sensitivity is significantly higher than that of a CROW without disorder.

Effect of resonator losses on the sensitivity of coupled resonator optical waveguide gyroscopes

Recently there has been a growing interest in microphotonic integrated optical gyroscopes. Here, we analyze the effect of resonator losses on the rotational sensitivity of a coupled resonator optical waveguide (CROW) gyroscope in comparison to a single passive resonator gyroscope of the same size. We show that the CROW gyro offers a superior sensitivity only for very low propagation losses. Moreover, the single ring resonator gyro is found to have a sensitivity that is stable over wide range of resonator losses as well as boasting greater sensitivities than the CROW gyro for propagation losses in the resonators exceeding 10⁻¹ dB/cm.

Effect of input–output coupling on the sensitivity of coupled resonator optical waveguide gyroscopes

We analyze how the evanescent coupling, κe, between the outermost resonators and input/output waveguides of an N-resonator coupled resonator optical waveguide (CROW) gyroscope affects the transmission and sensitivity to rotations. For constant coupling between resonators κ, rotation sensitivities increase as both κe→0 and κe→1 while between these two limits the sensitivity has a minimum. In the weak coupling regime, κe→0, the sensitivity is enhanced by Fabry–Perot oscillations due to the impedance mismatch at the input/output waveguide–CROW interface, while in the strong coupling regime, κe→1, the sensitivity is reduced because the outermost resonators no longer contribute to the CROW transmission. For small N the sensitivity is proportional to N2, while at larger N the sensitivity begins to decrease due to resonator losses.

Ultra-sensitive chip scale Sagnac gyroscope based on periodically modulated coupling of a coupled resonator optical waveguide

We analyze the sensitivity to inertial rotations Ω of a micron scale integrated gyroscope consisting of a coupled resonator optical waveguide (CROW). We show here that by periodic modulation of the evanescent coupling between resonators, the sensitivity to rotations can be enhanced by a factor up to 10(9) in comparison to a conventional CROW with uniform coupling between resonators. Moreover, the overall shape of the transmission through this CROW superlattice is qualitatively changed resulting in a single sharp transmission resonance located at Ω = 0s-1 instead of a broad transmission band. The modulated coupling therefore allows the CROW gyroscope to operate without phase biasing and with sensitivities suitable for inertial navigation even with the inclusion of resonator losses.

Rotation Sensitivity of Gyroscopes Based on Distributed-Coupling Loop Resonators

This paper reports a theoretical study of a recently proposed coupled-resonator optical waveguide (CROW) gyroscope consisting of a Sagnac interferometer in which light is coupled between adjacent loops in the coil. Simulations show that after optimization, this gyroscope is less sensitive to rotation than a conventional resonant fiber-optic gyroscope (RFOG) made of a single loop. Instead, the sensitivity decreases as the number of loops is increased. The fundamental reason is that in both types of sensors, the sensitivity is proportional to the group delay, and the maximum achievable group delay is limited in the same manner by loss. In addition, this CROW gyroscope utilizes multiple resonators instead of one, so it is much harder to stabilize against external perturbations. The RFOG still stands as the ideal candidate for a compact resonant gyroscope.

Chirped area coupled resonator optical waveguide gyroscope

We study the transmission of an optical field through a rotating coupled resonator optical waveguide (CROW) in which the size of the ring resonators changes from one ring to the next. We focus on symmetric integer wavelength chirps of the circumference of the rings relative to the central ring in the array. The transfer matrix method is used to obtain the transmission as a function of the inertial rotation rate Ω resulting from the Sagnac effect. Chirping increases the slope of the oscillations in the transmission as a function of Ω, which can be exploited to further enhance the rotation sensitivity beyond that of a CROW with uniform resonators.

Performance comparison of slow‐light coupled‐resonator optical gyroscopes

AbstractWe investigate the connection between group velocity and rotation sensitivity in a number of resonant gyroscope designs. Two key comparisons are made. First, we compare two conventional sensors, namely a resonant fiber optic gyroscope (RFOG) and an interferometric fiber optic gyroscope (FOG). Second, we compare the RFOG to several recently proposed coupled‐resonator optical waveguide (CROW) gyroscopes. We show that the relationship between loss and maximum rotation sensitivity is the same for both conventional and CROW gyroscopes. Thus, coupling multiple resonators together cannot enhance rotation sensitivity. While CROW gyroscopes offer the potential for large group indices, this increase of group index does not provide a corresponding increase in the maximum sensitivity to rotation. For a given footprint and a given total loss, the highest sensitivity is shown to be achieved either in a conventional RFOG utilizing a single resonator, or a conventional FOG.