Performance Of Optical Amplifiers Research Articles

THE WORKING PRINCIPLE OF OPTICAL AMPLIFIERS AND THEIR TYPES

One of the most important components of optical communication systems is optical amplifiers. By improving the performance of optical amplifiers, we will be able to achieve the optimality of the entire network. This article describes optical amplifiers and their types.

Comparative performance of optical amplifiers: Raman and EDFA

The in-line optical signal amplification is often used in optical communication systems to accomplish longer transmission distances and larger capacity. In this proposed paper, the operation of two types of optical amplifiers for 16×10 Gbps wavelength division multiplexing system had been examined by changing transmission distance from 10 to 200 km with a dispersion equals to 16.75 ps/nm/km. The analysis and design of such systems ordinarily includes many signal channels, nonlinear devices, several topologies with many noise sources, is extremely complex and effort-exhaustive. Therefore, theoretical studies with simulation CAD software of systems are become necessity to predict and optimize system performance. The comparison between EDFA and Raman has already explored by many researchers in varying ways in this work and to achieve obove objectives, the OptiSystem software was used to design the proposed fiber optic communications system and to simulate results. Performance for the present system was evaluated for parameters like bit error rate (BER), quality factor (QF), total gain with eye opening factor. It was saw that EDFA provides better results, in the maximal transmission distance 64% better than Raman amplifier, 57.5% for gain and 26.7% for maximum quality factor. As a future study a hybrid amplifier can produce better quality of amplification.

Performance of optical amplifiers with regard to the power penalties of a DWDM XGS-PON

Introduction:This article is the product of the research “Simulation level performance analysis of optical amplifiers for a DWDM XGS-PON network environment”, supported by the Research Group in New Technologies in Telecommunications (GNTT) of the University of Cauca during 2019.
 Problem:For the implementation of XGS-PON optical network architectures, amplification processes are required. These generate power penalties that lead to the presence of non-linear phenomena, significantly degrading network performance.
 Objective:To analyze the performance of a DWDM / XGS-PON network architecture, respecting the power penalties generated by implementing different types of optical amplifiers in different amplification modes.
 Methodology:Compilation of relevant bibliography on long-range network architectures with symmetric speeds of 10 Gbps.
 Results:Not working in the ideal region of amplification affects the performance of a DWDM XGS-PON network, generating a migration of a linear to non-linear propagation regime, due to the presence of power penalties such as FWM.
 Conclusion:With this investigation it is possible to determine which amplifier should be used according to the needs of the optical network, evaluating the different alternatives available in the market, depending on the cost, configuration and performance of the system.
 Originality:A new research is carried out for the performance of DWDM XGS-PON state-of-the-art network architectures, regarding the incidence of non-linear propagation phenomena.
 Restrictions:In some cases, the simulation tool requires a high consumption of machine resources and processing time.

Investigation of the performance of optical amplifiers for a 96 × 12 Gbps DWDM system using ultrasmall channel spacing

Ultrasmall channel spacing is a key concern for dense optical communication when incorporating a greater number of transmitting channels. In this work, we consider varying channel spacing ranging from 100 to 900 GHz in order to improve the performance of a 96 × 12 dense optical communication system. Analysis is carried out to obtain results in terms of quality factor, gain, cross talk, and eye closure. Power amplification is provided with the aid of an EDFA, Raman optical amplifier, SOA-SOA, and SOA. The EDFA was found to deliver the best results, with a quality factor of 25.5–30 dB, gain of 25.6–29.4 dB, and eye closure of 0.4–0.9 dB. It can thus be concluded that EDFA is the best choice in all aspects of dense wavelength-division multiplexing optical communication under conditions of ultrasmall channel spacing.

Theoretical Analysis of Directly Modulated Reflective Semiconductor Optical Amplifier Performance Enhancement by Microring Resonator-Based Notch Filtering

We demonstrate the feasibility of using a single microring resonator (MRR) as optical notch filter for enabling the direct modulation of a reflective semiconductor optical amplifier (RSOA) at more than tripled data rate than possible with the RSOA alone. We conduct a thorough simulation analysis to investigate and assess the impact of critical operating parameters on defined performance metrics, and we specify how the former must be selected so that the latter can become acceptable. By using an MRR of appropriate radius and detuning, the RSOA modulation bandwidth, which we explicitly quantify, can be extended to overcome the RSOA pattern-dependent performance limitations. Thus, the MRR makes the RSOA-encoded signal exhibit improved characteristics that can be exploited in practical RSOA direct modulation applications.

Study characteristics of 27 dBm Er/Yb co-doped/Raman hybrid amplifier (HA) compared to Er/Yb Co-doped fiber amplifier only

We present the gain and noise figure characteristics of Er-Yb co-doped/Raman hybrid amplifier (HA) compared to Er-Yb co-doped fiber Amplifier (EYDFA) only to improving the characteristics performance of optical amplifier. The work is done, at pump power of 27dBm≈500mW for both amplifiers (in the case of HA, 300mW for Er-Yb co-doped and 200mW for Raman amplifier (RA)). The gain and noise figure measured at (0.7 and 1m) lengths of Er-Yb co-doped, 25km Raman amplifier length and input signal power of (−40 to 10dBm) in the signal wavelength range (1525–1610nm). A large gain 40.33dB is obtained for the hybrid amplifier compared to Er-Yb co-doped amplifier only by increasing 7.33dB at 1530nm and −30dBm and a flat gain is observed in the all range of signal wavelength. Furthermore at lower input signal power −40dBm, the new hybrid amplifier, offer gain increasing to ∼13dB rather than its value at −30dBm signal power and 15dB in compared with Er-Yb co-doped amplifier only.

A review of the configuration and performance limitation parameters in optical amplifiers

Optical amplifiers are realised in a wide range of applications, such as metro – dense wavelength division multiplexing and cable television networks. These applications require the amplifier to provide a maximum output power level by accepting an input power near the saturation level. To obtain an ideal amplifier according to several parameters, the erbium concentration in the composite core glass, the optimum length of the fibre, the pump saturation and the input signal signalto-noise ratio must be critically studied and addressed. In this paper, we will review the types of optical amplifiers used in communication systems today as well as the parameters that limit the performance of optical amplifiers in the network, such as the noise figure, the gain saturation, the polarisation dependence gain and inhomogeneous broadening effects. Based on the performance limitation factor, we model the amplifier gain profile and the effect of the gain value on the network performance. Finally, we propose various configurations of an optical amplifier, and the advantages of each amplification technique are highlighted.

Quantum-dot semiconductor optical amplifier performance management under optical injection

The effect of an external beam on different characteristics of quantum-dot semiconductor optical amplifiers (QD-SOAs) has been investigated experimentally. It has been shown that injection of a relatively weak light beam at the gain transparency wavelength accelerates the full gain recovery time from 80 ps to 65 ps while it increases the saturation output power (SOP) by more than 2 dB if the beam resides in the gain region. The effect of the external beam on the fiber-to-fiber gain has been demonstrated at both the gain transparency wavelength and close to gain peak wavelength. These results are expected to be further enhanced by increasing the injected beam power, which has a peak value of ∼7 mW in the experiments.

Effects of inhomogeneous distribution of Si–Nc and Er ions on optical amplification in Si–Nc Er doped fiber

In this article, the effects of Si–Nc and Er3+ ions distribution parameters including inhomogeneous and homogeneous distribution profile are studied on the optical parameters such as gain, population inversion and Si–Nc induced losses. We have shown that by increasing of the concentration of Si–Nc particles the net gain and induced Si–Nc losses increased in homogeneous and inhomogeneous distributions. In practice, the homogeneous distribution of Er ions and Si–Nc is hard to be realized. Therefore, the inhomogeneous distributions of ions cased to perturb state in mode shape of optical signal then the investigations of those effects are important for high speed optical communications. In this article, a method for evaluation of the effects of inhomogeneous distribution of impurities on performance of optical amplifier is developed and the managing of the gain with use of suitable distribution functions is proposed.

Comparative analysis of the effects of internal lasing oscillation and external light injection on semiconductor optical amplifier performance

One of the key differences of a semiconductor optical amplifier (SOA) with internal lasing oscillation (ILO) from a SOA with external light injection (ELI) lies in a carrier-sharing mechanism. Since the internal lasing mode shares the same pool of carriers with the signals, the carriers (or photons) withdrawn from the circulating laser mode speed up the gain recovery. On the other hand, the external light injected into the SOA shortens the carrier recovery time through optical pumping without any carrier sharing involved. To find out a better scheme, we have made a comparative investigation on the effects of the ILO and ELI on the SOA performance. It turns out by way of simulation that the ELI scheme provides faster gain recovery, shorter carrier lifetime, and higher saturation power when the external injection power is higher than the internal lasing power. The performance enhancement is not so pronounced with the carrier-sharing mechanism, as the internal lasing mode itself gives rise to severe longitudinal spatial hole burning (LSHB). Nevertheless, the ILO scheme is preferable for linear-amplification applications. We also examine the use of the ELI for low-crosstalk optical amplifiers. It is found that the ELI scheme does not bring in a very strong resonance peak in the crosstalk, which appears in a SOA with ILO due to relaxation oscillations of the lasing mode. In comparison to the ILO in SOAs, the ELI into SOAs is likely to leave more optical gain for multi-channel amplification without any sacrifice on the crosstalk.

Optimum noise performance of optical amplifiers

The concept of noise figure F and noise measure M applicable to radio frequency and microwave amplifiers is reviewed and extended to cover optical amplifiers. Two noise figures are defined in the optical regime: one gives the ASE output, while the other gives the ratio of signal-to-noise ratios at the input and output. In the quantum regime, the lower limit on these optimum values is set by a generalization of Heisenberg's uncertainty relation. A Raman back-pumped fiber link with post-amplification with an erbium-doped fiber amplifier is used to illustrate the use of noise measure.

Optical amplifier performance in digital optical communication systems

Optical amplifiers are important building blocks in nowaday's optical communication system. Their noise behavior differs considerably from that of electrical amplifiers. Theory is reviewed and supplemented by examples that allow to estimate the performance of optical transmission systems. In particular, a correct optical noise figure definition is explained.

直接変調方式を用いた１０，０００ｃｈ‐ＷＤＭ／ＳＣＭシステムにおける光デバイスのアナログ特性の検討と光伝送系の設計

Recently several new WDM/SCM optical transmission systems have been developed, to enable a higher transmission capacity of access networks such as CATV. Analog transmission performance of optical amplifiers and optical filters is important for these systems. Yet, there have been few studies that addressed this issue. In this paper, the required performance of optical devices and a system design method are investigated. In our study, we focused on the technical issues essential for 10, 000-channel WDM/SCM (32 WDM×310 ch SCM) systems using cost-effective direct modulation schemes. First, the mechanisms of sub-carrier level variation and distortion generation caused by FM-AM conversion on optical filters were examined both theoretically and experimentally. The required bandwidth of optical filters suitable for these systems was calculated. We then estimated the optical distribution number depending on the optical signal power input into EDFAs. We found that a configuration using three cascaded EDFAs enables developing 10, 000-channel WDM/SCM systems with 8, 000 distributions.

Modelling of 980 nm pumped EDWAs: Spectroscopic variations associated to fabrication process

In this work the optical amplification, in the small signal regime, at 1.5 μm in Zn-diffused, proton exchange and reverse proton exchange Er3+-doped waveguide amplifiers (EDWAs) based on LiNbO3 under 980 nm excitation has been modelled, including the dominant up-conversion channel activated by this pumping wavelength. The overlapping integrals method has been used to investigate how the spectroscopic changes, induced by the waveguide fabrication technique, affect the optical amplifier performance. In particular, it has been found that either the amplifier threshold and the maximum gain achievable are spectroscopy-dependent and therefore fabrication-dependent.

Effect of saturation caused by amplified spontaneousemission on semiconductor optical amplifier performance

The authors have investigated theoretically the effect of amplified spontaneous emission (ASE) on the spatial distribution of the carrier density. Measures of the semiconductor optical amplifier (SOA) performance, such as gain, saturation power and noise figure are derived. It is shown that the saturation due to the ASE strongly affects the SOA performance for device lengths > 500 µm. The results are compared with experimental data and found to be in good agreement.

Practical limitations on optical amplifier performance

Practical issues are considered to determine if significant improvements in the sensitivity, of 1.55-μm optical receivers can be realized through the use of semiconductor laser preamplifiers. It is found that practical problems related to realizable values of population inversion parameter, input coupling losses, external optical filter requirements, polarization effects, and source laser stability make it unlikely that optical preamplifiers can approach their optimum performance at data rates below several Gbit/s. The most promising application of optical preamplifiers will therefore be to increase the sensitivity of receivers in future fiber optic communication systems operating at multigigabit data rates.

Theory of continuous-flow amplifiers and resonators

An analysis is made of the influence of overlap of optical beams on the performance of optical amplifiers and resonators. Complete analytic solutions are obtained for single- and double-pass amplifiers, and also for a resonator having mirrors with an intensity-dependent reflection coefficient. Simple equations are derived for their efficiencies.