Fiber phase conjugators: time- and frequency-resolved reflectivity

Undoped multimode quartz fibers based on stimulated Brillouin scattering (SBS) can be used as effective phase conjugators with low power threshold and high fidelity in a broad wavelength range from the near infrared over the visible down to the near ultraviolet. In the first investigation of fiber phase conjugators for input pulses with a coherence length of about 50 cm at 1064-nm wavelength, a saturation of the SBS reflectivity was observed at a value of about 50%, not considering the reflection losses on the fiber surface. To understand this saturation phenomenon, we analyzed the temporal and spectral structures of the transmitted and reflected light.