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In this paper, the performance of mid-link spectral inversion (MLSI)-based transmission is quantitatively compared to the performance for 'conventional' dispersion compensating fiber (DCF)-based transmission. Bit error rates (BER) are measured at optimized residual dispersion for all sixteen channels after 800km transmission in standard single mode fiber (SSMF). We show that for the MLSI-based configuration up to a decade of improvement in BER is obtained compared to the DCF based system. MLSI has the potential of lowering the cost of long haul transmission systems since instead of having multiple DCF modules per span only one spectral inverter is required for the whole transmission line. For spectral inversion, a polarization independent magnesium-oxide-doped periodically-poled lithium-niobate (MgO:PPLN) based subsystem was used.

We present experiments on a wavelength-flexible WDM/TDM-PON with an integrated reconfigurable OADM and a reflective electro-absorption modulator. We successfully transmit multiple wavelength channels of 10 Gbit/s each over 27 km SSMF in different bandwidth allocation schemes.

We discuss progress in optoelectronics and discuss how photonics can provide solutions to challenges in electronics, particularly where higher speed and lower energy is required

In this paper we describe experiments performed on a testbed of a novel dynamically reconfigurable access network capable of providing bandwidth on-demand to the end-users. Multiwavelength bidirectional transmission of 10 Gb/s channels in different bandwidth allocation schemes is achieved while sustaining substantial power budget to cover the attenuation of over 25 km standard SMF and related power penalties e.g. due to Rayleigh backscattering. Keywords: reconfigurable access network, FTTx, reflective electro-absorption modulator, optical add/drop multiplexer, microring resonators.

We present selected highlights in the progress of research in optical communication systems, addressing the role of photonics and providing special attention to routing, access, and to systems in the neighbourhood of the users.

In this paper, we show and analyze, for the first time, the static performance of integrated multi-stage cascade and tree spectral amplitude OCDMA en/decoders (E/Ds) which are fabricated in the low loss Si3N4–SiO2 material system. Combined with incoherent broad spectral sources these E/Ds enable cost-effective node deployment in an OCDMA passive optical network architecture. We discuss the design of a crucial component, namely the 2x2 3dB multi-mode interference coupler. Finally we show measured spectral codes of two-stage E/Ds and compare these with modeled ones.

The integration scale in Photonic Integrated Circuits will be pushed to VLSI-level in the coming decade. This will bring major changes in both application and manufacturing. In this paper developments in Photonic Integration are reviewed and the limits for reduction of device demensions are discussed

We discuss the influence of pseudo-random quaternary sequences on DQPSK transmission performance and present an efficient method to generate such sequences.

A necessidade de maior largura de banda, combinada com o aumento da busca por mobilidade, requer novos conceitos de interconexao de redes. Neste artigo e discutido o conceito de rede pessoal, uma rede inerentemente movel mas que necessita da rede de acesso como backbone de banda larga. O autor apresenta uma proposta de arquitetura resultante da relac;ao entre a fibra optica e a rede de area pessoal, analisando sua topologia basica e, a funcionalidade dos nos.

The most complex photonic ICs today have been developed for WDM applications. An overview of the most important integration technologies will be given and recent developments towards broader applications and higher integration densities will be discussed.

The tolerance to narrow spectral filtering in presence of chromatic dispersion is investigated for 111Gbit/s POLMUX-RZ-DQPSK. It is shown that the use of T-spaced equalisers is enabled by appropriate electrical filtering.

A novel reconfigurable access network architecture which enables the bidirectional transmission of 1.25-2.5 Gbit/s is described in this paper. Optical Network Units (ONUs) are equipped with a Reflective Semiconductor Optical Amplifier (RSOA) and Remote Nodes (RNs) are based on microring resonators. We also propose ONU upgrade to serve 10 Gbit/s per end-user. Next to the brief description of the architecture and transmission simulations some principle measurement results are presented which show the feasibility of the concept.

Dithering the bias current of a Reflective SOA can very effectively reduce coherent crosstalk, which can be a major limitation in WDM-PON performance using colourless RSOA-based ONUs. The power penalty was reduced from 5dB to 1dB.

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In this paper we propose a novel reconfigurable access network architecture which enables the bidirectional transmission of 1.25 - 2.5 Gbit/s. Optical network units (ONUs) are equipped with a reflective semiconductor optical amplifier (RSOA) and remote nodes (RNs) are based on microring resonators - both contribute to network transparency and flexibility. We also propose ONU upgrade to serve 10 Gbit/s per end-user. Next to the theoretical description and transmission simulations some principle measurement results are presented which show the feasibility of the concept.

We present some progress in the field of optical signal processing that could be utilized in all-optical packet switching. We demonstrate error-free 160 Gb/s optical wavelength conversion employing a single semiconductor optical amplifier. The gain recovery time of the semiconductor optical amplifier is greater than 90 ps. Assisted by an optical bandpass filter, an effective recovery time of 3 ps is achieved in the wavelength converter, which ensures 160 Gb/s operation. This optical wavelength converter can be controlled by a monolithically integrated optical flip-flop memory to route 80 Gb/s data-packets all-optically. The routing is realized without electronic control. The integrated optical flip-flop is based on two-coupled lasers, exhibits single-mode operation, has 35 dB contrast ratio between the states and switches state in about 2 ns. We demonstrate that the integrated flip-flop is able to control the optical wavelength converter up to 160 Gb/s. The system is capable of routing 80 Gb/s data packets with duration of 35 ns, separated by 15 ns of guard time.

We discuss the optimal filtering bandwidth for 42.8-Gbit/s RZ-DQPSK modulation through simulations and experiment. We verify that 42.8-Gbit/s RZ-DQPSK is tolerant to suboptimal filtering, and show that narrowband filtering can result in a sensitivity improvement.

An innovative design is presented enabling fine positioning of each individual fiber in a fiber array used in multiinput- and multioutput-port photonic integrated circuits. Hence, the coupling efficiency of lensed fiber arrays can be improved by eliminating the eccentricities of the lenses deposited on the individual fibers and the inaccuracies of the supporting V-groove substrates. In preparation, four different types of commercially available lensed fibers are characterized and coupling efficiencies to InP-based waveguides are determined in order to select the best applicable fibers for the array. The final fiber-tip position accuracy is within plusmn0.25 mum and this design is based on metal deformation by laser-welding-induced local heat. With this technique, laser-supported adjustment is possible, allowing the opportunity of fine-tuning the fiber-tip position of already secured parts in the subassembly. Owing to the accurate fiber-tip position and the assembly of the array with selected lensed fibers, coupling efficiencies of -2.9 to -3.5 dB are simultaneously measured for four fibers to InP-based waveguides with physical dimensions of 3 mum times0.6 mum. To compare these results, the performance of different types of regular, commercially available fiber arrays, whereby the fibers are mounted on silicon V-groove substrates, are determined. In contrast, the measured coupling efficiencies are of the order of -5.2 to -7.8 dB using similar InP-based waveguides An innovative design is presented enabling fine positioning of each individual fiber in a fiber array used in multiinput- and multioutput-port photonic integrated circuits. Hence, the coupling efficiency of lensed fiber arrays can be improved by eliminating the eccentricities of the lenses deposited on the individual fibers and the inaccuracies of the supporting V-groove substrates. In preparation, four different types of commercially available lensed fibers are characterized and coupling efficiencies to InP-based waveguides are determined in order to select the best applicable fibers for the array. The final fiber-tip position accuracy is within plusmn0.25 mum and this design is based on metal deformation by laser-welding-induced local heat. With this technique, laser-supported adjustment is possible, allowing the opportunity of fine-tuning the fiber-tip position of already secured parts in the subassembly. Owing to the accurate fiber-tip position and the assembly of the array with selected lensed fibers, coupling efficiencies of -2.9 to -3.5 dB are simultaneously measured for four fibers to InP-based waveguides with physical dimensions of 3 mum times0.6 mum. To compare these results, the performance of different types of regular, commercially available fiber arrays, whereby the fibers are mounted on silicon V-groove substrates, are determined. In contrast, the measured coupling efficiencies are of the order of -5.2 to -7.8 dB using similar InP-based waveguides

Error-free demultiplexing of 40-Gb/s base-rate channels out of a 160-Gb/s OTDM signal is achieved using a single SOA and an optical filter. Performance of demultiplexing 320 Gb/s using this technique is also presented.

We experimentally compare the nonlinear tolerance ofDWDM 21.4-Gbit/s RZ-DQPSK and 21.4-Gbit/s POLMUX-RZ-DPSK modulation over an 800-km SSMF straight-line. We show that the small depolarization penalty of POLMUX-RZ-DPSK makes it a possible alternative to RZDQPSK modulation for next-generation transmission.

The transmission performance of optical phase conjugation (OPC) is assessed with a special focus on the combination with the RZ-DQPSK modulation format. We show that when OPC is employed, significant performance improvement is obtained compared to conventional DCF based transmission.

Long-haul transmission (>1,000 km) with 1.6-b/s/Hz spectral efficiency is shown for the first time. Using polarization-multiplexed RZ-DQPSK, we demonstrate 40 x 85.6-Gb/s transmission over 1,700 km (18 x 94.5 km) of standard-single-mode fiber with 1-dB Q-margin.

To achieve a good coupling efficiency between a lensed fibre array and InP - based waveguides, fibre array alignment and fixation with nanometer scale accuracy is required. Laser supported actuation proves to be a promising technology for the realization of this goal. In this paper some fundamental issues about physics of lasersupport edactuation are presented. A number of different parameters of actuators were investigated. The objective of Our work was to gain knowledge about the influence of actuators geometry and laser beam properties on the peiformance of the actuators.

We demonstrate all-optical 131 0-to-15 50 nm wavelength conversion utilizing nonlinear polarization rotation in a semiconductor optical amplifier in between two standard single mode fibre based transmission links. Error-free operation at I 0 Gbitls is shown.

We discuss how all-optical signal processing might play a role in future all-optical packet switched networks. We introduce a concept of optical packet switches that employ entirely all-optical signal processing technology. The optical packet switch is made out of three functional blocks: the optical header processing block, the optical memory block and the wavelength conversion block. The operation principle of the optical packet switch is explained. We show that these three functional blocks can be realized by using the nonlinearities of semiconductor optical amplifiers. Some technologies in these three functional blocks are described. The header processor is realized using a Terahertz Optical Asymmetric Demultiplexer. We also describe a header pre-processor to improve the extinction ratio of the header processor output. In the optical memory block, we show that an all-optical memory can be obtained by using two coupled lasers that form a master-slave configuration. The state of the optical memory is distinguished by the wavelength of the master laser. We extend the concept to an optical memory can have multiple states. In the wavelength conversion block, we demonstrate a 160 Gbit/s wavelength conversion using a single semiconductor optical amplifier in combination with a well-designed optical bandpass filter. The semiconductor optical amplifier has a gain recovery time greater than 90 ps, which corresponds to a less than 20 GHz bandwidth for conventional wavelength conversion. We show that by properly using the optical bandpass filter, ultrafast dynamics in the semiconductor optical amplifier can be employed for wavelength conversion at ultrahigh bit-rates.

The BB Photonics develops reconfigurable access networks for providing the user with congestion-free access to virtually unlimited bandwidth. First design of reconfigurable access network architecture is presented in this paper together with preliminary specifications for components and modules. The simulation results of a reference network with wavelength agnostic optical network units based on a reflective semiconductor optical amplifier (RSOA) and a wavelength router based on ring resonators filtering characteristics give an encouraging perspective for further research. Consideration is given to a possible migration scenario.

In this paper we experimentally confirm the impairment due to nonlinear phase noise degradation in ultra-long haul 2x 10Gbit/s DQPSK WDM transmission over 7.100 km of SSMF

We discuss the performance of a multichannel 2 3 10 Gbit/s polarization-multiplexed differential phaseshift keying transmission system. Through simulations and transmission experiments we find that, despite the constant power envelope of non-return-to-zero phase-shift keying modulation formats, polarization multiplexing strongly reduces the nonlinear tolerance and transmission performance at a 2 3 10 Gbit/s line rate with multichannel transmission. This results in a 10 dB power penalty when comparing single- and nine-channel transmission. Additionally, multichannel impairments in differential phase-shift keying and on–off keying are compared for 2 3 10 Gbit/s polarization-multiplexed transmission. © 2005 Optical Society of America

We demonstrate that 80 Gb/s data-packets can be all-optically switched into two different ports employing an optical wavelength converter controlled by a monolithically integrated optical flip-flop memory. The optical wavelength converter consists of a semiconductor optical amplifier and an optical filter. The integrated optical flip-flop exhibits single-mode operation, has 35 dB contrast ratio between the states and switches state in about 2 ns. We show that the integrated flip-flop is capable to control an optical wavelength conversion up to 160 Gb/s. The system is capable of routing 80 Gb/s data packets with duration of 35 ns, separated by 15 ns of guard time.

We discuss an improved detection scheme for differential phase shift keying (DPSK) and differential quadrature phase shift keying (DQPSK), based on multi-symbol phase estimation (MSPE) through electrical signal processing. Using a recursive electrical signal processing algorithm, close to homodyne performance is obtained without a local oscillator at the receiver. In the presence of only Gaussian noise the proposed scheme yields a O.SdB and 1.8dB sensitivity improvement over self-homodyne detection, for DPSK and DQPSK respectively. lt furthermore improves robustness against impairments due to the influence of a finite laser linewidth and nonlinear phase noise.

Highly nonlinear fiber (HNLF) has shown to be a promising component for all optical signal processing at 160, 320 and 640 Gb/s data rates. We compare three demultiplexing techniques using a HNLF as the nonlinear medium. The first technique is based on cross phase modulation (XPM) in a nonlinear optical loop mirror. The second technique is based on XP M induced spectral broadening and filtering and the third technique is based on four wave mixing ( FWM). We demonstrate the demultiplexing from a 160 Gbls OTDM signal to a 10 Gb/s tributary in all three cases. We compare the three techniques on the basis of peiformance, complexity of implementation and the robustness.

Differential-quadrature phase-shift-keying (DQPSK) can, unlike on-off-keying (OOK), be impaired by nonlinear phase noise (NPN). It has been shown that optical phase conjugation (OPC) is an effective compensation scheme for NPN resulting from the ASE of EDFAs (ASE-NPN). In this paper we discuss the influence of NPN resulting from modulator imperfections (MJ-NPN). We show that MI-NPN can be compensated for through OPC, though shifts the optimum location of the OPC towards the middle of the transmission link.

A mechanical sub-assembly is presented enabling fine positioning and fixation of a lensed 4-fibre array to an integrated two-state AWG-based multiwavelength laser chip. The device operates as an all optical memory element used in optical packet switching and signal processing. The alignment accuracy between fibre array and chip is in the sub-micron range and possible in 4 degrees of freedom. The design minimizes postweld-shifts and enables re-positioning of the fibre array after the first fixation step. The mechanical sub-assembly is mounted in a package with a clamp method to reduce internal stress in the sub-assembly. The chip temperature is varied from 10 *C to 30 *C and stable coupling efficiency is measured.

An innovative design is presented enabling fine positioning of each individual fibre in a fibre array used in multi in- and output ports photonic integrated circuits. With this technology, the performance of fibre arrays can improve by eliminating the eccentricities of the lenses deposited on the individual fibres and the inaccuracies of the supporting V-groove substrates. The alignment accuracy is in the sub-micron range and this concept is based on metal deformation by laser-welding induced local heat. It enables us to precisely introduce stepbystep deformations in the constructions (despite the already secured position of the fibre tips and the adjustment construction). The smallest fine-tuning step is 0.05 µm and the fibres are aligned over a range of 10 µm – 25 µm. The performance of different types of regular commercially fabricated fibre arrays, with fibres mounted in silicon V-groove substrates has been determined in order to compare these with the performance of the proposed fibre array design.

We report on all-optical 1310 to 1550 nm wavelength conversion and NRZ-to-RZ data format conversion based on nonlinear polarization rotation in a single semiconductor optical amplifier.

Two active Mach-Zehnder interferometers are integrated together on a monolithic InP/InGaAsP photonic integrated circuit. Together they form a crucial component for optical signal processing: an optical memory element or set/reset flip-flop.

Dynamic optical routing in broadband access and local networks enables flexible service delivery, and improves the efficiency of network resources deployment, in particular for fibre-wireless networks.

We show in an 800km SSMF transmission experiment, that mid-link spectral inversion can be employed to reduce the effect of nonlinear phase noise (Gordon-Mollenauer noise) on DPSK by over two decades in BER.