Performance comparisons between semiconductor and fiber amplifier gain assistance in a recirculating frequency...

Area of Science:

• Photonics and Optical Communications
• Nonlinear Optics

Background:

• Recirculating frequency shifter (RFS) loops enable programmable multiline spectrum generation for optical communications.
• Semiconductor optical amplifiers (SOA) and erbium-doped fiber amplifiers (EDFA) are gain elements used in RFS systems.

Purpose of the Study:

• To investigate and explain performance variations between SOA and EDFA gain elements in RFS loops.
• To identify the impact of SOA nonlinearities on multiline spectrum generation.

Main Methods:

• Experimental comparison of SOA and EDFA performance within an RFS setup.
• Analysis of nonlinear effects, specifically four-wave mixing, in SOAs.
• Investigation of mitigation strategies for SOA-induced nonlinearities.

Main Results:

• Significant performance differences observed between SOA and EDFA gain elements.
• Four-wave mixing in SOAs was identified as a limiting factor for wavelength spacing.
• Increased RF drive frequency and deeper SOA saturation reduced four-wave mixing effects.

Conclusions:

• SOA nonlinearities, particularly four-wave mixing, critically affect RFS performance and multiline spectrum generation.
• Optimizing RFS drive frequency and SOA operating conditions can mitigate these nonlinear effects.
• Findings are crucial for developing fully flexible optical communications and frequency comb applications.