Effects of ASE noise and dispersion chromatic on performance of DWDM networks using distributed Raman amplifiers

We investigate effects of amplified spontaneous emission noise (ASE), noise figure (NF) and dispersion chromatic on the performance of DWDM networks using distributed optical fiber Raman amplifiers (DRAs) in two different pump configurations, i.e., forward and backward pumping. We found that the pumping configurations, ASE noise, and dispersion play an important role in network performance improving since it reduces noise figure and bit error rate (BER) of the system. Simulation results show that the lowest bit error rate and noise figure when using forward pumping configuration. Moreover, we have also compared ASE noise powers of the simulation with these of the experiment, they are match

Design and Optimization of Bismuth-Doped Fiber Amplifiers in the L+ Band (1600-1650nm)

This study investigates the design and optimization of bismuth-doped fiber amplifiers in the L+ band (1600-1650nm). The L+ band, as a promising optical communication frequency range, demands high-performance fiber amplifiers. However, existing amplifier technologies exhibit limitations in the L+ band, leading researchers to explore bismuth-doped fiber amplifiers to overcome these constraints. This paper first introduces the working principles and relevant background knowledge of L+ band fiber amplifiers. Subsequently, a comprehensive investigation of the gain characteristics of bismuth-doped fiber amplifiers in the L+ band is conducted. Based on theoretical models, a series of optimization designs, including adjustments of bismuth doping concentration, fiber length, and pump power, are carried out to achieve optimal performance. The proposed optimization scheme demonstrates significant performance improvements through MATLAB simulations and a genetic optimization algorithm, achieving high gain and excellent characteristics in the L+ band

Caracterização do regime transiente em EDFAs

Mestrado em Engenharia FísicaO presente trabalho propõe-se a relatar o desenvolvimento de duas interfaces gráficas para a simulação dos modelos estacionário e dinâmico de um amplificador de fibra dopada com érbio (EDFA), bem como a caracterização experimental do regime transiente em EDFAʼs originado por tráfego em modo de rajada. Relata também a validação experimental bem sucedida do modelo dinâmico no que toca a simular os referidos perfis de tráfego. É também descrita a avaliação experimental bem sucedida do impacto na geração de transientes de parâmetros importantes como o tamanho dos pacotes e o intervalo de tempo entre si, e a potência da bomba de um EDFA.This work relates the development of two graphical user interfaces for the simulation of both the dynamic and steady state models of an erbium doped fiber amplifier (EDFA), as well as the experimental characterization of the transient regime of EDFAs when amplifying bursty traffic profiles. The experimental validation of the numeric model for simulating bursty traffic is also reported. Experimental assessment of important parameters such as packet length, idle time duration and pump power was also performed and reported

Fabrication of Indium Arsenide Quantum Dot Structure for Semiconductor Optical Ampliers

Tämä diplomityö tutkii itseorganisoidusti valmistettuja InAs kvanttipisteitä InGaAsP:n ja InP päällä. Työn tavoitteena on ollut sellaisen kvanttipisterakenteen valmistaminen, joka soveltuu optiseen puolijohdevahvistimeen (SOA) tietoliikenneaallonpituuksilla. Työtä varten valmistettiin InAskvanttipistenäytteitä metallo-organisella kaasufaasiepitaksialla. Työn näytteet karakterisoitiin fotoluminesenssi- ja atomivoimamikroskopiamittausmenetelmillä. InAs-saarekkeiden koko ja tiheys optimoitiin ensiksi sopivaksi SOA-rakennetta varten valmistamalla itseorganisoituvia InAs-saarekkeita suoraan InP päälle. Näitä tuloksia käytettiin optimoidun InGaAsP-kerroksen sisältävän rakenteen valmistuksessa. Atomivoimamikroskopiamittaus paljasti, että optimoidun rakenteen InAs-saarekkeet olivat keskimäärin 10 nm korkeita ja 30 nm leveitä. Kvanttipisteiden luminesenssipiikin maksimi havaittiin 1.56 µm aallonpituudella 10 K lämpötilassa.In this thesis, the properties of self-assembled InAs/InGaAsP/InP quantum dots (QD) have been investigated. The focus of this work was to fabricate such a structure that can be used in a telecommunication wavelength semiconductor optical amplifier (SOA). The examined InAs QD samples were fabricated by metalorganic vapor-phase epitaxy technique. Photoluminescence (PL) and atomic force microscopy (AFM) were used in the characterization of the optical and the structural properties of the samples, respectively. InAs island size and the areal density was first optimized for SOAs by growing self-assembled InAs islands directly on InP. These results were used to finalize the structure containing also InGaAsP waveguide layer. The AFM results of the final structure show that InAs islands were grown quite homogenously on InGaAsP with an average height of 10 nm and an average base diameter of 30 nm. The low temperature PL peak of InAs/InGaAsP/InP quantum dots was tuned to 1.56 µm wavelength

バックエンド向けの(Er0.1Y0.9)2Zr2O7導波路増幅素子の集積化

次世代のDWDM通信に向けてMiDexの研究が進められている。従来の高屈折率Si導波路では高密度化が実現できるが、それに伴い非線形光学効果が大きくなり、またプロセストレランスが厳しくなる。MiDexのコア材料としてSi窒化物が有力候補である。大規模集積を可能にする為には、シリコン窒化物に対応した屈折率及び光信号の減衰を補償する光増幅媒質が必要である。最近、CMOSチップ上に形成する統合システムのバックエンドフォトニックスでは、光増幅に対する希望が高まっている。バックエンドフォトニックスを実現するには、多層金属統合技術と、MiDexのコア材料であるSiNxと、層間誘電体上の光増幅結晶の形成が必要である。そこで、本研究では、企業と共同開発したスパッタ装置「Digitally Processed DC Sputtering(DPDS)」を利用し、バックエンドフォトニクスに向けたプロセス構築を進めSiNx導波路と(Er_0.1Y_0.9)2Zr2O7光増幅素子を集積化することを目指す。従来、窒化シリコン(SiNx)の成膜にはプラズマCVDが用いられるが、残留水素の影響によるN-Hの赤外吸収が問題点として挙げられている。DPDSでは水素(化合物)を使用しないためこの赤外吸収を極力抑えられることが期待される。また材料選択の自由度が高く、高速成膜と高い制御性を有するDPDSを用いることで、多種の複合金属酸化膜のLayer-by-Layer堆積が可能となる。まず、SiNx成膜作製のプロセスについてですが、2個のSiターゲットをDCパルススパッタしながら、窒素ガスをパルス導入してSiNxの作製をした。1サイクル2[s]でSiスパッタ時間を2[s]として、窒素導入時間はずっとONにしている。このシーケンスで30分堆積させた。そして、(Er_0.1Y_0.9)2Zr2O7結晶作製のプロセスについてですが、装置内の背圧は5.0x10^-4[Pa]、成膜圧力を5.0[Pa]とした。Er/Y(Er:Y=1:9)、Zrのメタルターゲットを用いて組成比が(Er,Y):Zr:O=2:2:7となるよう各ターゲットのスパッタ時間を調整し、Si基板上に試料を40[W]で60分間堆積させた。酸素はEr/Yスパッタ中に10[sccm]供給した。以上の全プロセスをデジタルパターン発生し、DCパルススパッタを行った。そして、アニーリングは900℃、30分で行った。結果としましては、SiNx薄膜の作製ができました。(Er_0.1Y_0.9)2Zr2O7結晶作製はできましたが、結晶の配向性を改善する必要があります。電気通信大学202

High speed nonlinear optical components for next-generation optical communications

Electronic signal processing systems currently employed at core internet routers require huge amounts of power to operate and they may be unable to continue to satisfy consumer demand for more bandwidth without an inordinate increase in cost, size and/or energy consumption. Optical signal processing techniques may be deployed in next-generation optical networks for simple tasks such as wavelength conversion, demultiplexing and format conversion at high speed (≥100Gb.s-1) to alleviate the pressure on existing core router infrastructure. To implement optical signal processing functionalities, it is necessary to exploit the nonlinear optical properties of suitable materials such as III-V semiconductor compounds, silicon, periodically-poled lithium niobate (PPLN), highly nonlinear fibre (HNLF) or chalcogenide glasses. However, nonlinear optical (NLO) components such as semiconductor optical amplifiers (SOAs), electroabsorption modulators (EAMs) and silicon nanowires are the most promising candidates as all-optical switching elements vis-à-vis ease of integration, device footprint and energy consumption. This PhD thesis presents the amplitude and phase dynamics in a range of device configurations containing SOAs, EAMs and/or silicon nanowires to support the design of all optical switching elements for deployment in next-generation optical networks. Time-resolved pump-probe spectroscopy using pulses with a pulse width of 3ps from mode-locked laser sources was utilized to accurately measure the carrier dynamics in the device(s) under test. The research work into four main topics: (a) a long SOA, (b) the concatenated SOA-EAMSOA (CSES) configuration, (c) silicon nanowires embedded in SU8 polymer and (d) a custom epitaxy design EAM with fast carrier sweepout dynamics. The principal aim was to identify the optimum operation conditions for each of these NLO device configurations to enhance their switching capability and to assess their potential for various optical signal processing functionalities. All of the NLO device configurations investigated in this thesis are compact and suitable for monolithic and/or hybrid integration

Optical Fiber Amplifiers-Review

This paper reviews optical fiber amplifiers such asErbium doped fiber amplifiers EDFAs, many types of Ramanamplifiers RAs, Thulium doped fiber amplifiers, Tellurite-basedfiber Raman amplifiers, semiconductor optical amplifiers andfiber optic parametric amplifiers, principle of operation andconstruction. As these amplifiers are used for optical fibercommunication projects so we shall go through their maincharacteristics which are amplifier gain and span length,wavelength bandwidth and noise. Current repeater spacing andspeed of EDFA is in the range of 80-100 Km and 40 Gb/s whilethose for RA is in the range of 100-160 Km and 160-320 Gb/s.Each type of amplifier is suitable for certain applicationdepending on these characteristics. In metro/access networksthere are many add/drop locations resulting in high loss, coarsewavelength division multiplexing with about 20 nm separationbetween each channel as with this principle cheap multiplexingand laser transmitters are used