Investigation of the input power dynamic range for a cross gain modulation type wavelength-converter-cascaded optical regenerator

Abstract

SUMMARYWith advances in speed of optical communication, all-optical signal regeneration, in which degraded optical signals are regenerated by optical devices, has become desirable. Presently, schemes using cross-phase modulation in semiconductor optical amplifiers (SOA) and cross-absorption modulation in electroabsorption modulators (EAM) have been reported. However, optical signal regenerators based on cross-phase modulation have a narrow dynamic range of the input optical signal power, such as 2 dB, imposing severe restrictions on the operating conditions. With a view to enlarging the input dynamic range, we have proposed an optical signal regenerator consisting of cascaded wavelength converters using cross-gain modulation. In this scheme, the input and output characteristics of cross-gain modulation-based wavelength conversion are used in cascaded structure and the input/output characteristics in the low and high input optical power region are made nonlinear for optical signal regeneration. In the present paper, the fundamental characteristics of a CGCOR (a Cross-Gain modulation-type wavelength-converter-Cascaded Optical Regenerator) and the dynamic range of the input optical power are discussed. Detailed information is provided. In confirmation of the fundamental characteristics, nonlinearity was observed in the input and output characteristics of the CGCOR. In the study of the dynamic range, a result of 6 dB was obtained with a fixed probe power into the SOA. For the optimized first-stage probe power, the dynamic range is more than 11 dB. A reduction of relative intensity noise (RIN) was observed, and it is confirmed that this reduction contributes to improved received sensitivity of the regenerated light and to an expanded input power dynamic range. Hence, it is confirmed that the CGCOR has the potential to realize improved performance of optical signal regeneration operation.

40Gb/s 2R optical processing using monolithic integration of SOA and EAM

“…Using semiconductor as the active region for all optical 2R is one of the good solutions. Based on multiple quantum well material, such as semiconductor optical amplifier (SOA) and electroabsorption modulator (EAM) have been found with high nonlinear coefficients and also low cost, thus leading to high potential for nowadays all optical fiber networks [3][4]. The nonlinear properties in the saturated SOA and EAM devices can be used to simultaneously reduce the noise level of logic "1" level and improve the extinction ratio of transferred optical signal respectively.…”