Research On Digital Simulation And Control Of Laser Interferometer

In 1916,Albert Einstein first predicted the concept of gravitational waves based on his theory of General Relativity.Gravitational waves are caused by the accelerated motion of massive objects such as neutron stars or black holes.Gravitational waves are also known as "ripples in space-time".These ripples spread in all directions and travel at the speed of light,stretching and squeezing space.Gravitational waves have the characteristics of low frequency and small amplitude.The difficulty in detecting gravitational waves is that it interacts very weakly with matter.One advantage of the weakness of this interaction is that it does not decay or scatter on its way to the detector.However,interferometers used to detect gravitational waves are susceptible to seismic noise sources,thermal noise sources and optical noise sources.Therefore,the interferometers for detecting gravitational waves need to achieve very high sensitivity.There are two methods used to improve the signal-to-noise ratio,namely,enhanced the laser power,and lengthen the arm length.The topology of the interferometer can be optimized from both aspects.In this thesis,interferometers with various topologies are simulated using FINESSE software,and their sensitivity is analyzed.The combination of an optical cavity and a proportional-integral(PI)controller is also one of the commonly used optical systems in experimental quantum optics field.This paper designs an optimal PI controller of optical cavity based on the root mean square of error signal.The controller is implemented with a field-programmable gate array(FPGA)data acquisition board and Labview software.The overall gain of the controller is optimized by adopting the cavity transmission as optical power reference,such that cavity locking performance will not degrade as optical power varies.The long-term stability is verified experimentally.