Intracavity signal amplification system for next-generation gravitational-wave detectors

This article summarizes our study to develop an intracavity parametric signal amplification system for improving the sensitivity of a gravitational-wave detector at high frequencies to aim at an observation of a postmerger remnant of a binary neutron star collision. The detector configuration is based on a dual recycling interferometer and an optical parametric amplifier crystal is inserted into the signal recycling cavity. The cavity is detuned and an optical spring is generated for the differential motion of the two end mirrors. The amplifier converts the energy of the pump beam to the optical spring and the spring frequency can be enhanced to a few kilohertz. The system is contrasting to the squeeze injection technique commonly used in second-generation gravitational-wave detectors. Although both techniques use an optical parametric amplifier crystal, the squeeze injection reduces noise while signal amplification increases the signal to modify the optomechanical dynamics of the system.