Generation of low-noise frequency replicas in parametric frequency combs via phase-sensitive process

摘要

The ability to replicate (or multicast) an incoming optical signal in frequency domain without loss of fidelity is a holy grail for both fundamental physics and practical applications spanning from telecommunications to quantum processing. Dual-pump driven four-wave mixing in dispersion-engineered waveguides (e.g. optical fiber) is able to generate a large number of signal copies via optical frequency comb generation at precisely defined frequencies, in an ultrafast and coherent manner, however, this phase-insensitive (PI) parametric process also induces excess noise, which scales with the copy count under the ideal phase-matching condition. The reason for noise scaling in PI multicasting relies on the fact that with ideal phase matching (i.e. zero dispersion in the parametric device or mixer), all generated copies couple the same amount of quantum noise to each replica frequency, provided these copies are power equalized. We have found that this conclusion does not apply to mixers with small normal dispersion: conversely, the replica noise-figure (NF, defined as the ratio between the output and input signal-to-noise ratio) eventually approaches 6 dB, rather than scaling upward with increased copy creation. This discovery indeed points out possible direction towards low-noise or even noiseless spectral replication: parametric multicasting using multi-mode phase-sensitive (PS) process in highly-efficient mixer with finite normal dispersion. In this talk, we review the basic principle and realization of low-noise, four-mode PS multicasting. Recent experimental results of such multicaster in comparison to conventional EDFA preamplifiers are also demonstrated. Moreover, potential applications and technical challenges are discussed.