Multi-span transmission using phase and amplitude regeneration in PPLN-based PSA.

Area of Science:

• Optical Communications
• Nonlinear Optics
• Photonics

Background:

• Ultra-long-haul optical transmission systems face signal degradation from fiber nonlinearities and amplifier noise.
• Existing amplification techniques struggle to effectively suppress phase noise and regenerate signal amplitude.

Purpose of the Study:

• To demonstrate the efficacy of a periodically poled Lithium Niobate (PPLN) based phase sensitive amplifier (PSA) for ultra-long-haul optical data transmission.
• To evaluate the PSA's capability for simultaneous phase and amplitude regeneration in a recirculating fiber loop.

Main Methods:

• Implementation of an in-line PSA with integrated carrier recovery and phase locking within a recirculating fiber loop.
• Utilizing a periodically poled Lithium Niobate (PPLN) device as the core component of the phase sensitive amplifier (PSA).
• Transmission of a 28-Gb/s binary phase shift keying (BPSK) signal over extended distances.

Main Results:

• Achieved a significant PSA on-chip gain of up to +18 dB and an external black-box gain of +12 dB.
• Demonstrated substantial suppression of phase noise induced by fiber nonlinearity and intensity noise from amplified spontaneous emission (ASE).
• Successfully transmitted a 28-Gb/s BPSK signal over 5400 km, showcasing the PSA's regeneration capabilities.

Conclusions:

• The PPLN-based PSA effectively regenerates both phase and amplitude, mitigating key impairments in optical transmission.
• This technology enables robust ultra-long-haul transmission, paving the way for future high-capacity optical networks.
• The PSA acts as a crucial repeater, overcoming limitations of traditional optical amplifiers.