Parametric Amplifiers in Optical Communication Systems: From Fundamentals to Applications

Abstract

Optical parametric amplifiers (PAs) utilize highly efficient nonlinear effects in an optical fiber and they have the ability to operate in phase-sensitive mode. The inclusion of PAs in optical systems can give an ultimate limit for lumped amplified links in terms of achiev- able signal to noise ratio. The drawback is the complexity stemming from the requirement of phase matching a number of waves at each amplifier, phase lock, and the extra spec- trum consumed by idler waves. In this chapter, the theories of a parametric amplifier, including the quantum-optical equations, are given. The properties of the gain saturation and the noise figure are presented. Practical amplifier systems and their applications in phase-sensitive amplification, all-optical signal regeneration, and squeeze state generation are outlined. zero (CSRZ) modulation. Experiments are performed with driving frequencies 20 and 40 GHz. The sideband separation is twice the driving frequency of the modulator, while power at the carrier frequency is typically 23 dB below that of either sideband. A FBG is used to further suppress light at the carrier frequency in the pump path to (cid:1) 38 dB and to minimize interference in the DPSK signal when the waves are mixed.