All-optical wavelength conversion by semiconductor optical amplifiers

TLDR

Wavelength conversion is essential for optical networks, and semiconductor optical amplifiers provide cross‑gain and cross‑phase conversion methods. The study analyzes cross‑gain and cross‑phase wavelength conversion in semiconductor optical amplifiers. The authors examine how saturation filtering limits bandwidth and show that cross‑phase modulation in interferometric SOAs enables conversion at 20 Gb/s or higher. Cross‑gain modulation degrades extinction ratio at longer wavelengths, whereas monolithic interferometric converters deliver 10 Gb/s signals over 60 km of fiber.

Abstract

Following a brief introduction to the applications for wavelength conversion and the different available conversion techniques, the paper gives an in depth analysis of cross gain and cross phase wavelength conversion in semiconductor optical amplifiers. The influence of saturation filtering on the bandwidth of the converters is explained and conditions for conversion at 20 Gb/s or more are identified. The cross gain modulation scheme shows extinction ratio degradation for conversion to longer wavelengths. This can be overcome using cross phase modulation in semiconductor optical amplifiers that are integrated into interferometric structures. The first results for monolithic integrated interferometric wavelength converters are reviewed, and the quality of the converted signals is demonstrated by transmission of 10 Gb/s converted signals over 60 km of nondispersion shifted single mode fiber.