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We present a numerical bit-error rate investigation of 160–640 Gbit/s serial-to-parallel conversion by four-wave mixing based time-domain optical Fourier transformation, showing an inverse scaling of the required pump energy per bit with the bit rate.

A two-mode multiplexer based on a single grating coupler is proposed and demonstrated on a silicon chip. The LP01 and LP11 modes of a few-mode fiber are excited from TE0 and TE1 silicon waveguide modes.

A silicon micro-ring resonator is used to enhance the modulation speed of a 10-Gbit/s directly modulated laser to 40 Gbit/s. The generated signal is transmitted error free over 4.5 km SSMF. Dispersion tolerance is also studied.

RZ-DPSK to NRZ-DPSK format conversion in a silicon microring resonator is demonstrated experimentally for the first time at 41.6 Gb/s. The converted signal eye diagrams and bit-error-rate measurements show the good performance of the scheme..

We demonstrate a high-quality cavity-free 10 GHz 680 fs pulse source starting from a continuous wave (CW) laser. The pulse source is employed in a 640 Gbit/s on-off keying (OOK) OTDM data generation and demultiplexing experiment, where the error-free bit error rate (BER) performance confirms the high pulse quality. The pulse source is based on a linear pulse compression stage followed by two polarization-independent non-linear pulse compression stages. The linear pulse compression stage relies on a phase modulator, which is used to generate linear chirp and followed by a dispersive element to compensate the chirp. The non-linear pulse compression stages are based on self-phase modulation (SPM) in dispersion-flattened highly non-linear fibers (DF-HNLF). The pulse source is tunable over the C-band with negligible pedestal. © 2011 Optical Society of America.

This paper demonstrates the first mode-multiplexed system over 19-cell hollow-core photonic band gap fibre, at 2×20Gbps using the LP0,1 and LP2,1-like modes.

The effect of gain saturation on parametric amplification of 16-QAM signals is investigated in terms of signal distortion. The relative impact of gain saturation, nonlinear phase rotation and nonlinear phase noise is discussed. Experimental results at 14 GBd confirm the conclusions of the numerical analysis.

A silicon micro-ring resonator is used to enhance the modulation speed of a 10-Gbit/s directly modulated laser to 40 Gbit/s, demonstrating a potentially integratable transmitter design for high-speed optical interconnects.

Current technologies are fast approaching the capacity limit of single mode fibers (SMFs). Hollow-core photonic bandgap fibers (HC-PBGFs) are expected to provide attractive long-term solutions in terms of ultra-low fiber nonlinearities associated with the possibility of mode scaling, thus enabling mode division multiplexing (MDM). In this work, we demonstrate MDM over a HC-PBGF for the first time. Two 10.7 Gbps channels are simultaneously transmitted over two modes of a 30-m long 7-cell HC-PBGF. Bit error ratio (BER) performances below the FEC threshold limit (3.3 × 10−3) are shown for both data channels when the two modes are transmitted simultaneously. No power penalty and up to 3 dB power penalty at a BER of 10−9 are measured for single mode transmission using the fundamental and the LP11 mode, respectively. The performance of this exploratory demonstration is expected to improve significantly if advanced mode launching and detection methods are used.

A polarization splitter and rotator (PSR) based on a tapered directional coupler with relaxed fabrication tolerance is proposed and demonstrated on the silicon-on-insulator platform. The device is simply constructed by parallel-coupling a narrow silicon waveguide with a linearly tapered wider waveguide. Compared to previously reported PSRs based on a normal directional coupler, which suffer from stringent requirements on the accuracy of the narrow waveguide width, the introduced tapered structure of the wide waveguide can be used to compensate the fabrication errors of the narrow waveguide. In addition, only a single step of exposure and etching is needed for the fabrication of the device. Similar high conversion efficiencies are experimentally demonstrated for a narrow waveguide width deviation of 14 nm with large tolerance to the coupler length.

We have investigated the impact of reducing the electrical driving voltage in a 10-Gb/s optical duobinary transmitter from 100% to 25% of the full swing 2 V/sub /spl pi// of the Mach-Zehnder modulator. Reduction in the driving voltage enhances the signal extinction ratio and reduces the complexity of the transmitter while maintaining the high tolerance of this modulation technique to chromatic dispersion. Transmission at 10 Gb/s with 25% of the full swing over a 182-km unrepeatered span of uncompensated standard single-mode fiber has been achieved with low sensitivity penalty.

A novel scheme exploiting saturation effects in fiber optical parametric amplifiers using a degenerate dual-pump phase sensitive configuration is proposed and analyzed. QPSK phase regeneration is numerically demonstrated in a nonlinear interferometer structure.

The effect of third-order dispersion on the saturated-gain in fiber optical parametric amplifiers is experimentally demonstrated. A possible interpretation in terms of dispersive waves, which change the power transfer to the signal, is presented.

Numerical optimization of dual-pump degenerate-idler phase sensitive amplifiers is performed for Al-doped and standard highly nonlinear fibers. Design considerations for operating the PSAs at an optimum combination of gain and extinction ratio are discussed.

Ultra-wide band signal generation using a silicon micro-ring resonator tuned to a NRZ-DPSK modulated optical carrier is proposed and demonstrated. Tuning of the coupling regions of the micro-ring enables the synthesis of monocycle pulses.

This paper presents a detailed experimental characterization of the relative intensity noise (RIN) transferred from the pump to the signal in one-pump phase insensitive fibre optic parametric amplifiers. We extend an existing experimental and theoretical work towards higher frequencies, showing for the first time a strong wavelength dependence of the RIN transfer over a 30 GHz modulation frequency range. Good agreement is obtained between the measured RIN transfer and the predictions of a simple theoretical model.

Fibre optic parametric amplifiers (FOPAs) are versatile devices for amplification at arbitrary wavelengths, as well as a wide range of optical signal processing applications, including switching, wavelength conversion, regeneration, pulse generation etc [1]. Transfer of intensity fluctuations from the pump to the signal (hereafter referred to as relative intensity noise transfer, RINT) affects the quality of the amplified signal due to the pump power dependence of the gain and the ultrafast nature of the Kerr nonlinearity [1–4]. For high-speed signal processing applications, the pump may be modulated at several hundreds of GHz or Gbit/s and it is therefore important to quantify the RINT at such high frequencies. To the best of our knowledge, the frequency dependence of pump-to-signal RINT has only been investigated theoretically and experimentally in single-pump FOPAs for low intensity modulation frequencies (IMFs) (

We propose a generic optical network design for future avionic systems in order to reduce the weight and power consumption of current networks on board. A three-layered network structure over a ring optical network topology is suggested, as it can provide full reconfiguration flexibility and support a wide range of avionic applications. Segregation can be made on different hierarchies according to system criticality and security requirements. The structure of each layer is discussed in detail. Two network configurations are presented, focusing on how to support different network services by such a network. Finally, three redundancy scenarios are discussed and compared.

A 640 Gbit/s NRZ OTDM signal has been successfully generated for the first time by format conversion of a 640 Gbit/s OTDM signal from RZ to NRZ. First, a coherent 640 Gbit/s OTDM RZ signal is generated by wavelength conversion of the original incoherent OTDM signal utilizing Kerr switching in a highly nonlinear fiber. Second, RZ-to-NRZ format conversion is achieved in a specially designed silicon microring resonator with FSR of 1280 GHz, Q value of 638, high extinction ratio and low coupling loss to optical fiber. A 640 Gbit/s NRZ OTDM signal with very clear eye-diagram and narrower bandwidth than both the original incoherent 640 Gbit/s and the wavelength converted coherent 640 Gbit/s RZ OTDM signals has been obtained. Bit error ratio measurements show error free (

Although patterning effects (PEs) are known to be a limiting factor of ultrafast photonic switches based on semiconductor optical amplifiers (SOAs), a simple approach for their evaluation in numerical simulations and experiments is missing. In this work, we experimentally investigate and verify a theoretical prediction of the pseudo random binary sequence (PRBS) length needed to capture the full impact of PEs. A wide range of SOAs and operation conditions are investigated. The very simple form of the PRBS length condition highlights the role of two parameters, i.e. the recovery time of the SOAs as well as the operation bit rate. Furthermore, a simple and effective method for probing the maximum PEs is demonstrated, which may relieve the computational effort or the experimental difficulties associated with the use of long PRBSs for the simulation or characterization of SOA-based switches. Good agrement with conventional PRBS characterization is obtained. The method is suitable for quick and systematic estimation and optimization of the switching performance.

We demonstrate two-mode multiplexing at 2×10.7 Gbps over 7-cell hollow-core photonic band gap fiber. BER performances below FEC threshold limit (3.3×10−3) are shown for both data channels.

We comprehensively analyze the demodulation of wavelength division multiplexed (WDM) non return-to-zero differential phase-shift keying (NRZ-DPSK) signals by a single microring resonator. Simultaneous demodulation of multiple 40 Gbit/s WDM NRZ-DPSK channels is demonstrated using a single silicon microring resonator with free spectral range (FSR) of 100 GHz. Bit error measurements show very good performance for both through and drop port demodulations for all channels, and the drop port demodulation exhibits better wavelength detuning tolerance than for demodulation using a Mach-Zehnder delay interferometer (MZDI).

We demonstrated for the first time 80 to 40 Gb/s OTDM-DPSK demultiplexing using a single SOA assisted by offset-filtering. Error free performance is achieved with an average power penalty of 5.5 dB.

The pump-to-signal intensity modulation transfer in saturated degenerate FOPAs is numerically investigated over the whole gain bandwidth. The intensity modulation transfer decreases and the OSNR improves when the amplifier operates in the saturation regime.

In the history of optical fiber communications, there were key milestones in system R&D that helped usher in new phases of the field. Critical advances such as terrestrial systems, WDM, submarine systems, coherent communication and fiber in the access will be highlighted.

We experimentally investigate and verify simple and efficient methods for characterizing the patterning effects (PE) of SOA-based optical switches. The onset of PE saturation is well predicted by the theory. An experimental method to capture the maximum PE is developed.

This paper analyzes experimentally and by numerical simulations an optical frame retimer and synchronizer unit for 10 Gbit/s Ethernet input frames. The unit is envisaged to be applied in the design of an optically transparent router for Optical Time Division Multiplexed (OTDM) links, aggregating traffic from several 10 Gbit/s Ethernet (10 GE) links. The scheme is based on time-lenses implemented through a combination of a sinusoidally driven optical phase modulation and linear dispersion. Our analysis extracts the operation range of the scheme used for synchronization and retiming in the context of 10 Gbit/s Ethernet, considering the frequency offset to the local clock within the specified standard tolerance (i.e.  1 MHz for 10 Gbit/s Ethernet) and the Ethernet frame size (i.e. up to 1526 bytes). We also provide preliminary design insights to increase the operation range.

The feasibility of transmitting 0.87 Tbit/s dual polarization D8PSK-OTDM over 110 km is, for the first time, demonstrated along with 0.44 Tbit/s single polarization D8PSK-OTDM over 220 km in conventional 55-km span SMF+DCF link.

We demonstrate the first all-optical 2R regeneration of 25 Gbit/s NRZ data based on hysteresis in a DFB laser. The scheme results in BER improvement, exhibits low power consumption and is effective after fiber transmission.

It is shown how introducing a limited rise time to the driving signal enables all-optical clock recovery of NRZ-DPSK signals generated using a phase modulator. A Fabry-Perot filter is used to generate the optical clock.

We report on time-of-flight experimental measurements and numerical calculations of the group-index dispersion in a photonic crystal waveguide realized in silicon-on-insulator material. Experimentally group indices higher than 230 has been observed. Numerical 2D and 3D time-domain simulations show excellent agreement with the measured data.

A 32.1 Gbit/s RZ-D8PSK modulated signal was transmitted through 160 km SSMF with optical phase conjugation after 80 km. The phase conjugation was performed by four wave mixing.

A WDM phase-modulated Radio-over-Fibre link using digital coherent detection is experimentally demonstrated. 3 times 50 Mb/s WDM transmission of a BPSK modulated 5 GHz RF carrier is achieved over 25 km.

21.4 Gbit/s baseband DQPSK and 1.25 Gbit/s phase modulated RoF was transmitted over 80 km SSMF using polarization multiplexing.

In this work we discuss saturation performance of a fiber optic parametric amplifier. A simple numerical model is described and applied to specific cases. A system experiment using a saturated amplifier illustrates a 4 dB improvement in required signal to noise ratio for a fixed bit error ratio.

A novel DSP based coherent receiver for phase modulated radio-over-fiber optical links is reported. Using the proposed digital receiver, signal demodulation of 1.25 Gb/s ASK-modulated 10 GHz RF carrier is experimentally demonstrated.

Input power dynamic range enhancement and amplitude regeneration of highly distorted signals are demonstrated experimentally for 40 Gbit/s RZ-DPSK in a single-pump fibre parametric amplifier with 22 dB smallsignal gain.

The impact of XPM from NRZ modulated channels on an 8-level phase modulated channel in a WDM system was investigated. Requirements on launch power are found. 400 km transmission was achieved with negligible penalty.

By combining differential 8-ary phase shift keying with wavelength division multiplexing, we present transmission of 8 channel multilevel modulation with 3 bits per symbol. We observed no error-floor down to BER = 10 .

We report the first experimental demonstration of amplitude equalization of 40 Gb/s RZ-DPSK signals using saturation of FWM in a HNLF. We show effective power penalty reduction after wavelength conversion of an amplitude distorted signal.

Generation of WSK up to 35 Gb/s with reuse of the wavelength tones for polarization multiplexing two independent 40 Gb/s DPSK signals is demonstrated, including transmission over a 50 km fiber link.

We report on a bidirectional 85 km long reach PON system supported by distributed fiber Raman amplification with a record 7.5 Gb/s remote carrier modulated upstream signal by employing a reflective SOA-EA monolithically integrated circuit.

We examine different transmitter structures in electronic pre-distortion optical communication systems, and show that practical requirements due to electrical bandwidth limitation and driving signals amplitude and delay mismatches have a significant impact on system performance.

We report on direct numerical calculations and experimental measurements of the group-index dispersion in a photonic crystal waveguide fabricated in silicon-on-insulator material. The photonic crystal is defined by a triangular arrangement of holes and the waveguide is carved out by introducing a one-row line defect. Both the numerical and experimental methods are based on the time of flight approach for an optical pulse. An increase of the group index by approximately 45 times (from 4 to 155) has been observed when approaching the cutoff of the fundamental photonic bandgap mode. Numerical 2D and 3D simulations of pulse dynamics in the waveguide made by the time-domain method shows excellent agreement with measured data in most of the band. These group index values in a photonic crystal waveguide are to the best of our knowledge the largest numbers reported so far by direct tracking of pulse propagation.

Orthogonal amplitude shift keying/differential phase-shift keying (ASK/DPSK) labeling is a promising approach to ultrahigh packet-rate routing and forwarding in the optical layer. However, the limitation on the payload extinction ratio (ER) is a detrimental effect for network scalability and transparency. This paper presents theoretical and experimental studies of ASK/DPSK labeling. It proposes that dc-balanced 8B10B coding can greatly improve ER tolerance, which in turn leads to better system performance. By using the 8B10B coding method, the paper demonstrates transmission and optical label swapping for a 40 Gb/s ASK payload and a 2.5 Gb/s DPSK label with an overall power penalty of 3.3 dB for the payload and 0.3 dB for the label. The experimental results also show that the ER is allowed to be as high as 12 dB

An integrated Michelson delay interferometer structure making use of waveguide gratings as reflective elements is proposed and fabricated by direct ultraviolet writing. Successful return-to-zero alternate-mark-inversion signal generation using phase-to-intensity modulation conversion is demonstrated up to 40 Gb/s using the device. Compared to other implementations, the device is compact, inherently stable, and allows for easy customization of the pulsewidth by proper positioning of the gratings on a single coupler structure.

Wavelength conversion of a 40-Gb/s return-to-zero differential phase-shift keying signal is demonstrated in a highly nonlinear photonic crystal fiber (HNL-PCF) for the first time. A conversion efficiency of -20 dB for a pump power of 23 dBm and a conversion bandwidth of 31 nm, essentially limited by the gain bandwidth of erbium-doped fiber amplifiers, are obtained in only 50-m dispersion-flattened HNL-PCF with nonlinear coefficient equal to 11 W/sup -1//spl middot/km/sup -1/. This experiment demonstrates the potential of four-wave mixing in HNL-PCF as a modulation format and bit rate transparent wavelength conversion mechanism in future high-speed systems.

In future all optical networks one of the enabling technologies is tunable elements including reconfigurable routers, switches etc. Thus, the development of a technology platform that allows construction of tuning components is critical. Lately, microstructured optical fibers, filled with liquid crystals, have proven to be a candidate for such a platform. Microstructured optical fibers offer unique wave-guiding properties that are strongly related to the design of the air holes in the cladding of the fiber. These wave-guiding properties may be altered by filling the air holes with a material, for example a liquid crystal that changes optical properties when subjected to, for example, an optical or an electrical field. The utilization of these two basic properties allows design of tunable optical devices for optical networks. In this work, we focus on applications of such devices and discuss recent results.

The transmission feasibility of a 40 Gbit/s DPSK payload with in-band SCM (subcarrier multiplexing) labeling at 3 GHz subcarrier frequency is experimentally verified over 80 km NZDSF (nonzero dispersion shifted fiber).