Theoretical analysis of wavelength conversion based on four-wave mixing in light-holding SOAs

• Published in: IEEE journal of quantum electronics 2004-01, Vol.40 (1), p.31-40
• Main Authors: GONG, Pei-Miin, HSIEH, Jyh-Tsung, LEE, San-Liang, JINGSHOWN WU
• Format: Article
• Language: English
• Subjects: Charge carrier density; Current measurement; Density measurement; Efficiency; Exact sciences and technology; Four-wave mixing; Frequency conversion; harmonic generation, including high-order harmonic generation; Fundamental areas of phenomenology (including applications); Harmonic generation, frequency conversion; Laser optical systems: design and operation; Light; Nonlinear optics; Optical noise; Optical parametric oscillators and amplifiers; Optical wavelength conversion; Optics; Physics; Resonators, cavities, amplifiers, arrays, and rings; Semiconductor device noise; Semiconductor optical amplifiers; Solar energy; Spontaneous emission; Wavelength measurement
• ISSN: 0018-9197; 1558-1713
• DOI: 10.1109/JQE.2003.820833

We propose to use an additional injection beam of short wavelength to enhance the wavelength conversion that utilizes the four-wave-mixing (FWM) effect in a semiconductor optical amplifier (SOA). With this scheme, the assist light can increase the saturation intensity without sacrificing the gain of an SOA, and this leads to an increase in conversion efficiency. A numerical method dealing with various FWM mechanisms, such as amplified spontaneous emission (ASE) noise, longitudinal spatial hole burning, and wavelength-dependent gain spectrum, is developed to predict the static characteristics of our scheme. The carrier densities are nonuniformly distributed along the longitudinal direction of the SOA as a result of the ASE effect, which affects the measurement of the wavelength-dependent transparent current. The effects of an assist light on saturation output power and conversion efficiency are analyzed in detail. The analysis shows that using an assist light can improve both the conversion efficiency and signal-to-background-noise ratio (SBR) for SOAs of different lengths. The degree of improvement depends on the bias condition, assist light wavelength, and the device geometry. The study for the device optimization reveals that a compromise between conversion efficiency and SBR must be made to choose the device length.