Development of KAGRA Photon Calibrator for Hardware Injection Test

Abstract

無中文摘要Photon calibrator (Pcal) is an independent device that can provide artificial input to an interferometric gravitational-wave detector by exerting the radiation pressure of its own laser on the test mass mirror in the interferometer. It not only can provide a fiducial length reference for calibration purpose but also can inject simulated gravitational waveforms to verify the response of the interferometer to the astrophysical gravitational waves, known as hardware injection test. Currently, the injection signals (Excitations) are produced by KAGRA Digital System(DGS). These signals change the intensity of PCal Laser by acousto-optic modulators (AOM) inside the transmitter module of PCal. However, if the output signal from the Digital System is noisy, it force AOM to modulate laser intensity according to such noisy control signal, resulting in noisy radiation force on the End Test Mirror (ETM). In this dissertation, we implemented and characterized an analog filter known as the De-Whitening filter. We installed it between Digital System output and PCal to address the noise problem while keeping the accuracy of injected signals.