Optimization of the incident condition for a CAT self-pumped phase conjugator by erasure

We propose and demonstrate a new method for optimizing the incident condition in a CAT self-pumped phase conjugate mirror by using strong erasure light. The erasure of the grating inside the crystal can be treated as shortening the crystal thickness. A reduced coupling strength is defined by considering an extra fanning beam. This extra fanning beam is along the direction for obtaining the largest coupling strength and is not responsible for generating a phase conjugate wave. The experimental results show that the reduced coupling strength can predict the optimal erasure length for obtaining the highest reflectivity of the conjugate wave.