年 2024 體積 37 問題 3 37 DOI: 10.58030/JVE.370301.6 SEMICONDUCTOR OPTICAL AMPLIFIER (SOA) FOUR- WAVE MIXING (FWM) WAVELENGTH CONVERSION WITH IMPROVED SIGNAL OUTPUT QUALITY David I. Forsyth 1 , Kanar R. Tariq 2 , and Ahmed Jamal Abdullah Al-Gburi 1 , Riyam Alaa Johni 3 1 Department of Electronics and Computer Engineering Technology (JTKEK), Universiti Teknikal Malaysia Melaka (UTeM), Jalan Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia. 2 Faculty of Engineering & Computer Science, Qaiwan International University (QIU), Sulaymaniyah, Iraq \ Technical College of Informatics, Sulaimani Polytechnic University (SPU), Sulaymaniyah, Iraq. 3 Computer Science Department, Kurdistan Technical Institute (KTI), Sulaymaniyah, Iraq. ABSTRACT: In this work, we have substantially improved the measured signal-to-noise S/N ratio and Q-factors in a four-wave mixed (FWM) converted wavelength signal in a dual semiconductor optical amplifier (SOA) arrangement by saturating each SOA component in an optical fibre communications link. The results show considerable improvements in both measurands of the converted signal by virtue of SOA gain saturation. Keywords: semiconductor optical amplifier (SOA), four-wave mixing (FWM), signal-to-noise ratio (S/N). INTRODUCTION The Semiconductor Optical Amplifier (SOA) device has become a topic of major interest over the years, both academically and commercially [1 - 3]. This tiny, special multi-functional device has been the subject of numerous academic papers. However, the eternal battle between practical performance and cost-effectiveness will always continue to dominate the device’s future in an industrial sense, particularly when competing with the single functioning erbium-doped fiber amplifier (EDFA) [4]. As well as possessing gain [5, 6], one of the many special non-linear functions of the SOA has is that of wavelength conversion [7] – and, in particular, four-wave mixing (FWM), which is a non-linear optical phenomenon that has been analysed extensively in the literature [8]. FWM is a well-known effect based on third-order nonlinear light– matter interactions, and can combine ultrafast time resolution with energy and wavevector selectivity to enable the exploration of dynamics inaccessible by linear methods [7]. The FWM mechanism in a SOA has also gained much attention recently [8 - 13] as a viable and highly attractive wavelength conversion technique for the future - in an era where there exist daily demands on speed, bandwidth and the avoidance of bottlenecks – and all of this vs. costs. Most people using the internet these days desire to download as speedily as possible. Therefore, higher quality and more cost-effective wavelength conversion is needed now more than ever, mainly due to these kinds of pressures put on it by the web in this modern, financially-orientated age. The FWM process in an SOA normally consists of two input optical waves, each having the same state of polarization, coupled into a saturated SOA [9]. Inside the active region of the SOA, the beatings of the two co- propagating waves modulate the carrier density, and therefore generate dynamic gain and index gratings. This nonlinear interference produces new waves, hence the term four-wave mixing [10, 11]. Another key feature of an SOA is its ability to reduce intensity noise by virtue of its saturation characteristics [14 - 19]. The SOA has been shown extensively to reduce intensity noise by virtue of this attribute. SOA noise suppression effectively works due to the non-linear slope of the curve in its saturation region, at which point the output from the input is effectively “squashed” which means the intensity noise reduces [20, 21]. Recently, a saturated SOA was used for Brillouin amplification noise suppression [22]. Here, low distortion over wider frequency range was shown for noisy spectral lines after modulation with 72 Gb/s 64-QAM signals with the incorporation of a saturated SOA. Also, a saturated SOA was used as an effective and universal intensity noise suppression technique for single-frequency fiber lasers at 1.5 μm [23]. In work done in [12, 13], the inherently