Vibration-insensitive Mode Cleaner For Generation Of Low-frequency Squeezed Light

Mode cleaner plays a important role in the generation and measurement systems of the low-frequency squeezed light.The mode cleaner in the balanced hoyodyne-detector system can purify the spatial mode,improve the polarization degree of light field and stabilize the relation phase and spatial direction of squeezed vacuum light field and local light field,allowing the balanced hoyodyne-detector system to achieve a high enough interference contrast to improve detection efficiency.In order to reduce the response of the mode cleaner to the audio vibration,the low vibration sensitivity of the mode cleaner must be guaranteed in the measurement system.Low vibration sensitivity can reduce the measurement deviation caused by phase noise and change the phenonmenon that the degree of the squeezed in the detection results decreases.Environmental vibration and temperature must be taken into account in order to make the mode cleaner vibration insensitive.Vibration is transmitted through the support structure to the cavity,causing the cavity to undergo elastic deformation in the direction of random forces.The deformation of the cavity couples in other directions due to non-zeroPoisson ratio.So vibration isolation measures must be taken to ensure that cavity is insensitive to vibration.The support structure of the cavity can be optimized by static simulation for the environmental disturbance of the static acceleration.In addition,the dynamic analysis of the cavity structure can also be carried out so that the mode cleaner can be applied under the vibration frequency of the intrinsic basement membrane to achieve the purpose of suppressing the vibration sensitivity of the cavity.For the effect of temperature on cavity length,it can be reduced by precision control temperature and by using material with a small cofficient of thermal expansion.The main contects of this paper include:(1)Introducing the development status of low-frequency squeezed light,the optical properties of the triangular ring cavity and the necessity of the study vibration insensitive mode cleaners.(2)Static stress analysis of the mode cleaner using finite element technology includes:(1)Quantitative simulation of cavity deformation in the gravity field causes cavity length changes,and determines the optimal parameters of vibration-insensitive support structure.(2)The relationship between temperature and thermal expansion coefficient is introduced,and the deformation diagram of the cavity at zero expansion temperature is simulated.(3)Through model analysis and random vibration analysis,we get the working frequency range of the mode cleaner suitable for the generationof the squeezed light ih low-frequency band.