提出具有高群有效折射率的双环级联作为核心元件的谐振式平面光波导陀螺结构,基于光学Sagnac原理得到了双微环耦合谐振式光学陀螺理论灵敏度与群有效折射率的一般表达式和双环与单环陀螺系统的灵敏度关系,并由耦合模理论方法得到了双环系统耦合器的两个透射系数对应的群有效折射率变化情况.在环腔半径R1=R2=100μm、环腔传输损耗系数t1=t2=0.95的情况下,针对环与环之间耦合器和环与波导之间耦合器透射系数对群有效折射率的不同影响,得到了最大群有效折射率的产生条件.采用文中参数(R=100μm,t=0.95)计算的单环谐振式陀螺灵敏度为(104—105) °/h,而双环级联谐振系统理论灵敏度能够达到10°/h.该研究对微环耦合谐振腔在角速度检测上的应用有重要的意义.
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 = 100μm and ring transmission loss coefficient tl = 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 pm and t = 0.95, the sensitivity of a single ring resonator gyroscope is (10 4--10 5) °/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 sen