Loop Mirror Multi-wavelength Brillouin Fiber Laser Utilizing Semiconductor Optical Amplifier and Fiber Bragg Grating

In this paper, the development of loop mirror multi-wavelength Brillouin fiber laser utilizing semiconductor optical amplifier and fiber Bragg grating is successfully demonstrated. A multi-wavelength BFL structure employs a single mode fiber that acts as the gain medium, while the fiber Bragg grating act to reflect the signals and semiconductor optical amplifier is used to amplify the signal are employed to produce multiple channels. The implementation of difference parameter for semiconductor optical amplifier driven current, Brillouin pump power, Brillouin pump wavelength and length of single mode fiber, plays an important role in producing the multiple channels. The highest number of channels which is 15 achieved once 9 km of SMF length, semiconductor optical amplifier current at 800mA and low Brillouin pump power at -12 dBm are utilized in the laser structure. Furthermore, the implementation of semiconductor optical amplifier and reflectivity of fiber Bragg grating in Brillouin fiber laser structure gives a better performance in producing the multiple channels

Study of interwell carrier transport by terahertz four-wave mixing in an optical amplifier with tensile and compressively strained quantum wells

Interwell carrier transport in a semiconductor optical amplifier having a structure of alternating tensile and compressively strained quantum wells was studied by four-wave mixing at detuning frequencies up to 1 THz. A calculation of transbarrier transport efficiency is also presented to qualitatively explain the measured signal spectra

Wavelength conversion up to 18 nm at 10 Gb/s by four-wave mixing in a semiconductor optical amplifier

We characterize the conversion bandwidth of a four-wave mixing semiconductor optical amplifier wavelength converter. Conversion of 10-Gb/s signals with bit-error-rate (BER) performance of <10^-9 is demonstrated for wavelength down-shifts of up to 18 nm and upshifts of up to 10 nm

Numerical analysis of pulse pedestal and dynamic chirp formation on picosecond modelocked laser pulses after propagation through a semiconductor optical amplifier

A numerical analysis, based on a modified Schrodinger equation, of the formation of pulse pedestals and dynamic chirp formation on picosecond pulses after propagation through a semiconductor optical amplifier is presented. The numerical predictions are confirmed by an experiment that utilises the frequency resolved optical gating technique for the amplified pulse characterisation

Novel design for noise controlled semiconductor optical amplifier

The use of semiconductor optical amplifiers (SOA) in optical communications networks has so far been limited due to their inherent large noise figure (NF) compared to Erbium Doped Fibre Amplifiers. Therefore improvement of the noise performance of SOAs is critical to their widespread adoption in future networks. We propose to reduce the NF of the SOA by introducing a lasing cavity lateral to the axis of amplification of the device. The carrier density within the cavity is clamped at the lasing threshold. It is thus possible to engineer the carrier density distribution along the active waveguide by controlling the cavity design. According to our simulations, some of the cavity designs lead to a reduction of the noise figure in this novel SOA

Suppression of beating noise of narrow-linewidth erbium-doped fiber ring lasers by use of a semiconductor optical amplifier

Beating noise in narrow-linewidth erbium-doped fiber ring lasers puts severe limitations on applications of the lasers. We demonstrate the suppression of beating noise in fiber ring lasers by using a semiconductor optical amplifier in the laser cavity, which acts as a high-pass filter. Two different ring structures are presented as examples to demonstrate this beating noise suppression

Folded-path self-pumped wavelength converter based on four-wave mixing in a semiconductor optical amplifier

A four-wave mixing wavelength converter with no external pump laser and very low input signal power requirements is characterized. The wavelength conversion occurs inside a high-reflection/antireflection coated semiconductor optical amplifier pigtailed with a fiber Bragg grating. The pump signal is provided by the lasing mode at the Bragg wavelength. A 1-mW optical signal modulated at 2.5 Gb/s is converted over 9 mm with error rates below 10^-9

Semiconductor optical amplifiers: performance and applications in optical packet switching [Invited]

Semiconductor optical amplifiers (SOAs) are a versatile core technology and the basis for the implementation of a number of key functionalities central to the evolution of highly wavelength-agile all-optical networks. We present an overview of the state of the art of SOAs and summarize a range of applications such as power boosters, preamplifiers, optical linear (gain-clamped) amplifiers, optical gates, and modules based on the hybrid integration of SOAs to yield high-level functionalities such as all-optical wavelength converters/regenerators and small space switching matrices. Their use in a number of proposed optical packet switching situations is also highlighted

半導体光増幅器を用いた光デジタル・アナログ相互変換

　デジタル・アナログ変換(D/A変換)とアナログ・デジタル変換(A/D変換)は，電子デバイスや光学システム内でデジタル信号とアナログ信号を接続するための重要な機能であり，通信ネットワークを含む幅広い分野で利用されている．近年，デジタル信号処理技術の発達に伴い，より高性能なD/A変換器やA/D変換器の需要が高まっている．しかし，電気的なD/A変換器やA/D変換器は，ジッタ制限，電磁干渉，RC遅延などの高速動作における固有のボトルネックを有している．よって，コストや複雑さを犠牲とし，1つのシステムに複数の電気的なD/A変換器やA/D変換器を様々な手法で統合し，高速な変換を実現している．一方，光信号処理は電気信号処理の限界を克服できるため，光D/A変換器や光A/D変換器の実現が注目されている．主に特殊な光ファイバ内で発生する非線形光学効果を用いた光D/A変換器や光A/D変換器が報告されているが，構成が複雑であり，高いパワーが必要といった課題がある．　半導体光増幅器(SOA)は，小型かつ低消費電力であり，高い非線形性を有していることから，波長変換などの光信号処理デバイスとしても利用されている．SOAを用いた光D/A変換や光A/D変換は，相互利得変調を用いた手法がそれぞれ1件ずつ報告されており，2 bitの変換を実証しているが，高分解能化には多数のSOAが必要となる等の課題が存在する．　周波数チャープは，SOAで発生する特異な現象であり，デバイスの屈折率変化に基づいて周波数変動を誘導する．これまでに，SOAのチャープ特性が，長波長側への周波数シフトであるレッドチャープと短波長側への周波数シフトであるブルーチャープが異なる特性を有することを示されている．このレッドチャープを活用した光A/D変換器が提案されており，構成な構成かつ低入力パワーで8レベルの光量子化に成功している．　本論文では，SOAのブルーチャープを用いた光D/A変換の検討を行い，2 bitの光D/A変換を実証した．そして，その変換性能を微分非線形性(DNL)，積分非線形性(INL)，有効ビット数(ENOB)を用いて評価した．さらに，ブルーチャープを用いた光D/A変換とレッドチャープを用いた光A/D変換を組み合わせた，2 bitの光デジタル・アナログ相互変換を実証した．周波数チャープを用いた光D/A変換と光A/D変換は，単一のSOAを用いた簡素な構成とモノリシック集積の可能性を有している．得られた結果は，アナログ信号とデジタル信号を光領域で相互接続する手法として，提案方式の有用性を示した．電気通信大学201