Showing papers by "Periklis Petropoulos published in 2011"
TL;DR: An optical fast Fourier transform scheme is demonstrated that provides the necessary computing power to encode lower-bitrate tributaries into 10.8 and 26.0 Tbit s-1 line-rate orthogonal frequency division multiplexing (OFDM) data streams and to decode them from fibre-transmitted OFDM data streams.
Abstract: Optical transmission systems with terabit per second (Tbit s-1) single-channel line rates no longer seem to be too far-fetched. New services such as cloud computing, three-dimensional high-definition television and virtual-reality applications require unprecedented optical channel bandwidths. These high-capacity optical channels, however, are fed from lower-bitrate signals. The question then is whether the lower-bitrate tributary information can viably, energy-efficiently and effortlessly be encoded to and extracted from terabit per second data streams. We demonstrate an optical fast Fourier transform scheme that provides the necessary computing power to encode lower-bitrate tributaries into 10.8 and 26.0 Tbit s-1 line-rate orthogonal frequency division multiplexing (OFDM) data streams and to decode them from fibre-transmitted OFDM data streams. Experiments show the feasibility and ease of handling terabit per second data with low energy consumption. To the best of our knowledge, this is the largest line rate ever encoded onto a single light source.
544 citations
TL;DR: An all-optical signal processing architecture is reported that enables, for the first time, multilevel all-Optical quantization of phase-encoded optical signals.
Abstract: The exponentially increasing capacity demand in information systems will be met by carefully exploiting the complementary strengths of electronics and optics. Optical signal processing provides simple but powerful pipeline functions that offer high speed, low power, low latency and a route to densely parallel execution. A number of functions such as modulation and sampling, complex filtering and Fourier transformation have already been demonstrated. However, the key functionality of all-optical quantization has still not been addressed effectively. Here, we report an all-optical signal processing architecture that enables, for the first time, multilevel all-optical quantization of phase-encoded optical signals. A four-wavemixing process is used to generate a comb of phase harmonics of the input signal, and a two-pump parametric process to coherently combine a selected harmonic with the input signal, realizing phase quantization. We experimentally demonstrate operation up to six levels
159 citations
TL;DR: The transfer of an ultrastable microwave frequency is demonstrated by transmitting a 30-nm-wide optical frequency comb from a mode-locked laser over 86 km of installed optical fiber.
Abstract: We demonstrate the transfer of an ultrastable microwave frequency by transmitting a 30-nm-wide optical frequency comb from a mode-locked laser over 86 km of installed optical fiber. The pulse train is returned to the transmitter via the same fiber for compensation of environmentally induced optical path length changes. The fractional transfer stability measured at the remote end reaches 4×10−17 after 1600 s, corresponding to a timing jitter of 64 fs.
99 citations
12 Dec 2011
TL;DR: The first gridless networking field trial with flexible spectrum switching nodes over 620 km field fibre links achieves successful transport, spectrum switching and defragmentation achieved for mixed line signals including 555G and coherent 100G.
Abstract: We report the first gridless networking field trial with flexible spectrum switching nodes over 620 km field fibre links. Successful transport, spectrum switching and defragmentation achieved for mixed line signals including 555G and coherent 100G.
76 citations
06 Mar 2011
TL;DR: In this paper, an input-idler-free non-degenerate phase sensitive amplifier (PSA) configuration was introduced for simultaneous phase and amplitude regeneration of quadrature phase shift keyed (QPSK) signals demonstrated at symbol rates up to 56 Gbaud.
Abstract: We introduce a novel input-idler-free non-degenerate phase sensitive amplifier (PSA) configuration and use it for simultaneous phase and amplitude regeneration of quadrature phase shift keyed (QPSK) signals demonstrated at symbol rates up to 56 Gbaud.
42 citations
TL;DR: In this article, the authors report the first detailed implementation of a 2D finite element method (FEM) through a commercial FEM solver that can be universally applied to calculate the Brillouin gain characteristics of optical fibers with arbitrary refractive index profiles and material composition, including radially asymmetric and microstructured optical fibers (MOFs).
Abstract: We report the first detailed implementation of a 2-D finite-element method (FEM) through a commercial FEM solver that can be universally applied to calculate the Brillouin gain characteristics of optical fibers with arbitrary refractive index profiles and material composition, including radially asymmetric and microstructured optical fibers (MOFs). Experimental results on various fabricated solid and MOFs are presented that demonstrate the widespread applicability and high accuracy of the proposed technique, which should prove to be an invaluable tool for designing novel optical fibers with tailored Brillouin response for a wide range of applications.
36 citations
TL;DR: In this paper, a stable optical beat-signal with frequency >; 160 GHz is produced by injection-locking two narrow-linewidth semiconductor lasers emitting at frequencies spaced by the beat-frequency to a low-jitter 10-GHz optical comb.
Abstract: A stable optical beat-signal with frequency >; 160 GHz is produced by injection-locking two narrow-linewidth semiconductor lasers emitting at frequencies spaced by the beat-frequency to a low-jitter 10-GHz optical comb. The generated beat-signal with broadband noise suppression of >; 75 dB is temporally compressed by factors of up to four in a high stimulated Brillouin scattering threshold aluminosilicate highly nonlinear fiber. The generated subpicosecond pulses have a root mean square (rms) timing jitter below 150 fs measured over 1 s.
24 citations
18 Sep 2011
TL;DR: In this article, phase sensitive amplification in a highly nonlinear lead-silicate W-type fiber was demonstrated in a 1.56m sample of the fiber for a total launched power of 33dBm.
Abstract: We experimentally demonstrate phase-sensitive amplification in a highly nonlinear lead-silicate W-type fibre. A phase-sensitive gain swing of 6dB was observed in a 1.56m sample of the fibre for a total launched power of 33dBm.
13 citations
TL;DR: A regenerative all-optical grooming switch for interconnecting 130 Gbit/s on-off keying (OOK) metro/core ring and 43 Gbits/s-OOK metro/access ring networks with switching functionality in time, space, and wavelength domains is demonstrated.
Abstract: A regenerative all-optical grooming switch for interconnecting 130 Gbit/s on-off keying (OOK) metro/core ring and 43 Gbit/s-OOK metro/access ring networks with switching functionality in time, space, and wavelength domains is demonstrated. Key functionalities of the switch are traffic aggregation with time-slot interchanging functionality, optical time division multiplexing (OTDM) to wavelength division multiplexing (WDM) demultiplexing, and multi-wavelength 2R regeneration. Laboratory and field demonstrations show the excellent performance of the new concept with error-free signal transmission and Q-factors above 20 dB.
11 citations
TL;DR: In this article, an all-optical technique for the mitigation of timing jitter in short pulse transmission systems is presented. The technique relies on pulse preshaping followed by optical switching in a periodically poled lithium niobate waveguide via cascaded second harmonic and difference frequency generation.
Abstract: We demonstrate an all-optical technique for the mitigation of timing jitter in short pulse transmission systems. The technique relies on pulse preshaping followed by optical switching in a periodically poled lithium niobate waveguide via cascaded second harmonic and difference frequency generation. The original data pulses are shaped into flat-top pulses to avoid conversion of their timing jitter into pulse amplitude noise at the output of the waveguide. Pulse retiming is confirmed by temporal measurements, while bit-error-rate measurements confirm good noise performance for the system.
10 citations
06 Mar 2011
TL;DR: More compact, stable, and efficient configuration of a recently developed regenerator is presented in this article, at data rates up to 56 Gbit/s using white phase noise for the first time.
Abstract: More compact, stable, and efficient configuration of a recently-developed regenerator is presented. The regenerator is assessed at data rates up to 56 Gbit/s using white phase noise for the first time.
17 May 2011
TL;DR: In this article, the performance of various commercially available lasers in terms of their absolute frequency stability, lineshape and linewidth, and frequency noise is evaluated using an optical ruler.
Abstract: We characterize and compare the performance of various commercially available lasers in terms of their absolute frequency stability, lineshape and linewidth, and frequency noise. The frequency stability, linewidth and lineshape are evaluated using an ‘optical ruler’ - a carrier-envelope stabilized optical comb. The frequency noise is measured over an extended spectral range starting from 2 Hz. The performed analysis gives data necessary when deciding which laser to use in a particular application.
15 May 2011
TL;DR: In this paper, the authors presented remote measurements from a large-scale interferometric optical sensor system, using a 500km optical transmission link between interrogator and sensor array, 3 times longer than the longest reported so far to the knowledge.
Abstract: We present remote measurements from a large-scale interferometric optical sensor system, using a 500km optical transmission link between interrogator and sensor array, 3 times longer than the longest reported so far to our knowledge. A phase noise floor of -80dB re 1 rad·Hz-0.5 peak was achieved (equivalent to 1 mPa·Hz-0.5). 256 sensors may be interrogated via the link using a single fibre pair, making the system highly suitable for remote interrogation of large scale sensor arrays for applications such as seismic and acoustic sensing. Eight amplified 125km spans using standard Corning SMF-28 single mode fibre form the transmission link.
TL;DR: In this paper, a phase-regenerative wavelength conversion in periodically poled lithium niobate waveguides is proposed and experimentally demonstrated using either: a single-stage implementation based on a simultaneous combination of two cascaded second-order nonlinear effects in a single periodically-poled lithium Niobate (LiNiobate) waveguide, or a two-stage approach where two separate devices are used in sequence to give rise to the same nonlinear effect.
Abstract: We propose and experimentally demonstrate phase-regenerative wavelength conversion in periodically poled lithium niobate waveguides, using either: a single-stage implementation based on a simultaneous combination of two cascaded second-order nonlinear effects in a single periodically poled lithium niobate waveguide, or a two-stage implementation where two separate devices are used in sequence to give rise to the same nonlinear effects. The phase regeneration properties of the proposed wavelength conversion schemes are also investigated.
06 Mar 2011
TL;DR: The first field-trial of a phase and amplitude regenerator highlighting the practicality of the technology is reported and sensitivity improvement and mitigation of transmission-induced noise with the regenerator placed in-line or at the receiver is demonstrated.
Abstract: We report the first field-trial of a phase and amplitude regenerator highlighting the practicality of the technology. Sensitivity improvement and mitigation of transmission-induced noise with the regenerator placed in-line or at the receiver is demonstrated.
TL;DR: It is concluded that the tuning bandwidths of both cascaded processes should be similar in the pulsed pump regime once the pump pulse bandwidths approach that of SFG (i.e. the cSHG/DFG bandwidth is not limited by the CW SHG bandwidth).
Abstract: We report a systematic and comparative study of the acceptance bandwidths of two cascaded quadratic nonlinear processes in periodically poled lithium niobate waveguides, namely cascaded second-harmonic generation and difference-frequency generation (cSHG/DFG) and cascaded sum-frequency generation and difference-frequency generation (cSFG/DFG). We first theoretically and experimentally study the acceptance bandwidths of both the individual second-harmonic generation (SHG) and sum-frequency generation (SFG) processes in the continuous wave (CW) and pulsed-pump regimes. Our results show that the SHG bandwidth is approximately half that of the SFG process in the CW regime, whereas the SHG acceptance bandwidth can approach the CW SFG bandwidth limit when pulsed-pump is used. As a consequence we conclude that the tuning bandwidths of both cascaded processes should be similar in the pulsed pump regime once the pump pulse bandwidths approach that of SFG (i.e. the cSHG/DFG bandwidth is not limited by the CW SHG bandwidth). We confirm that this is the case experimentally.
18 Sep 2011
TL;DR: In this article, a technique to nonlinearly generate precise spectral shapes in an adaptable and power-efficient fashion was proposed, and the generation of a spectrum with a 7-nm 0.5-dB bandwidth was demonstrated to prove the validity of the approach.
Abstract: We report a technique to nonlinearly generate precise spectral shapes in an adaptable and power-efficient fashion. The generation of a spectrum with a 7-nm 0.5-dB bandwidth is demonstrated to prove the validity of the approach.
26 Jun 2011
TL;DR: In this paper, the application of phase sensitive fiber optical parametric devices for the regenerative processing of high baud rate optical signals is discussed, and it is shown how it is possible to derive phase regeneration in signals with more than two levels of phase encoding.
Abstract: We discuss the application of phase sensitive fiber optical parametric devices for the regenerative processing of high baud rate optical signals. We present recent advances in phase-sensitive amplification technology and its application to the regeneration of phase-encoded signals. By combining four wave mixing based parametric effects in highly nonlinear optical fibers and injection locking assisted synchronisation of multiple coherent lasers, we demonstrate how it possible to derive phase regeneration in signals with more than two levels of phase encoding.
18 Sep 2011
TL;DR: In this paper, arc fusion splicing of highly nonlinear soft glass fiber with a flattened, near-zero dispersion profile at 1.55μm to conventional silica fibre is demonstrated.
Abstract: We report arc fusion splicing of highly nonlinear soft glass fibre with a flattened, near-zero dispersion profile at 1.55μm to conventional silica fibre. Reasonable splice loss values and watt-level power handling are demonstrated.
22 May 2011
TL;DR: In this paper, the authors combine the nonlinear element (a highly nonlinear fiber - HNLF) with a programmable phase and amplitude filter, which they use as a pulse shaper, allowing power-efficient and flexible sculpturing of the output spectrum, which is no longer tied directly to the characteristics of the pulse source used at the input.
Abstract: Recent developments in optical fibre technology have allowed significant advances in the nonlinear generation and tailoring of broadband spectra. Much work in this direction has focused on the optimisation of the properties of the optical fibres used for the nonlinear pulse propagation. In this work, we combine the nonlinear element (a highly nonlinear fibre - HNLF) with a programmable phase and amplitude filter, which we use as a pulse shaper. This architecture allows power-efficient and flexible sculpturing of the output spectrum, which is no longer tied directly to the characteristics of the pulse source used at the input. The pulse shaping function is obtained by application of the inverse split-step Fourier method (ISSFM) [1], which uses the desired output spectrum and the HNLF characteristics as its input parameters [2]. As an example of the application of this technique, we study the generation of broadband flat (third-order super-Gaussian) spectra starting from a 10GHz mode-locked pulsed laser (MLL). Here we present our design procedure and a first experimental validation of the technique.
01 May 2011
TL;DR: In this article, the regeneration of binary and quadruple phase encoded signals using phase sensitive amplification in fibers is reviewed and a review of recent results regarding regeneration is presented. But the results are limited.
Abstract: We review recent results regarding regeneration of binary and quadruple phase encoded signals using phase sensitive amplification in fibers.
18 Sep 2011
TL;DR: In this article, the authors discuss recent advances in phase sensitive amplification technology and review its application to the regeneration of multi-level phase-encoded signals, and discuss the application of phase-sensitive amplification to phase-decoded signals.
Abstract: We discuss recent advances in phase-sensitive amplification technology and review its application to the regeneration of multi-level phase-encoded signals.
18 Sep 2011
TL;DR: In this paper, the inherent suitability of fiber optical parametric amplifiers (FOPAs) to the amplification of optical combs was demonstrated, combining gain, spectral shaping, frequency translation, effective spectral broadening and low noise amplification.
Abstract: We demonstrate the inherent suitability of fiber optical parametric amplifiers (FOPAs) to the amplification of optical combs, combining gain, spectral shaping, frequency translation, effective spectral broadening and low noise amplification.
01 May 2011
TL;DR: OFDM has emerged as a promising modulation technique in long-haul and access optical networks and can be met with powerful digital signal processors, and especially by exploiting all-optical signal processing.
Abstract: OFDM has emerged as a promising modulation technique in long-haul and access optical networks. The computational complexity of the format can be met with powerful digital signal processors, and especially by exploiting all-optical signal processing.
01 Jan 2011
TL;DR: The search for the maximum bit rate × distance was based on the principle of infinite bandwidth of the optical fiber that let us to imagine transmission of enormous capacities over transoceanic distances as discussed by the authors.
Abstract: Progress in optical communications has been one of the key factors for the enormous growth of the ICT sector, and, in particular, of the Internet phenomenon. Such a progress has been driven by experimental successes that have been obtained in the last three decades in several laboratories all over the world, and we have witnessed a fantastic challenge among such labs to reach record targets such as maximum bit rate, maximum propagation distance, higher performance, maximum efficiency, and, recently, minimum energy consumption. The search for the maximum bit rate × distance was based on the principle of infinite bandwidth of the optical fiber that let us to imagine transmission of enormous capacities over transoceanic distances, especially after the invention of the optical amplifier.
22 May 2011
TL;DR: In this paper, the phase-squeezing capability of phase sensitive amplifiers (PSAs) is exploited to perform simultaneous amplitude regeneration in the saturation regime of phase-shift keying signals.
Abstract: Phase noise introduced during transmission both from optical amplifiers and nonlinear interactions between channels represents a significant limiting factor to data transmission when advanced modulation formats such as (differential) phase-shift keying, (D)PSK, or quadrature phase shift keying, QPSK, signals are used to increase the network capacity [1]. Consequently, the development of all-optical techniques capable of eliminating phase (and ideally amplitude as well) noise from multi-level phase signals is of great interest. Phase regeneration of (D)PSK signals can be achieved directly by exploiting the phase-squeezing capability of phase sensitive amplifiers (PSAs) [2], which can be operated in the saturation regime to perform simultaneous amplitude regeneration. The main challenge in realising practical PSA-based regeneration is to stabilize and maintain a phase relationship between the PSA pump(s), the signal and any idlers present at the PSA input. This is complicated in practice by the fact that phase-encoded signals have a suppressed carrier. Moreover, even if the carrier can be extracted, it would generally incorporate any noise generated during data transmission. To overcome these issues a regenerative scheme has recently been demonstrated [3“5] which simultaneously allows carrier recovery and carrier noise suppression. The resulting cleaned carrier is then used to phase-lock the locally generated pumps with the incoming data prior to signal regeneration in a degenerate two-pump PSA [4–5]. In this scheme two important technologies were used: injection locking of semiconductor lasers to remove high frequency amplitude and phase noise during the carrier recovery process [6] and specialized highly nonlinear fibres (HNLFs) with an alumino-silicate core and a linear strain gradient applied along the length to increase the stimulated Brillouin scattering (SBS) threshold [7] in order to allow higher PSA gains. Figures 1 (a) and (b) show example constellation diagrams at the input/output of the regenerator for noisy input DPSK signals at 56Gbaud illustrating the regenerative performance achieved.
06 Mar 2011
TL;DR: In this paper, a 2.2m long sample of lead-silicate W-index profile fiber with nonlinear coefficient of 820W−1km−1 and exhibiting low and flat dispersion across the C-band was used in an all-optical 160-to-40Gbit/s demultiplexing scheme based on four-wave mixing.
Abstract: A 2.2m long sample of lead-silicate W-index profile fiber with nonlinear coefficient of 820W−1km−1 and exhibiting low and flat dispersion across the C-band is used in an all-optical 160-to-40Gbit/s demultiplexing scheme based on four-wave-mixing.
06 Mar 2011
TL;DR: In this paper, a novel scheme of phase-sensitive wavelength conversion was proposed based on a combination of cascaded second-order nonlinear effects in two cascaded periodically poled lithium niobate waveguides.
Abstract: We propose and experimentally demonstrate a novel scheme of phase-sensitive wavelength conversion, based on a combination of cascaded second-order nonlinear effects in two cascaded periodically poled lithium niobate waveguides.
18 May 2011
TL;DR: In this article, a combination of parametric effects in fibers and optical injection locking of lasers is used to observe phase regeneration in signals with multiple levels of phase encoding, which is called phase-sensitive amplification.
Abstract: We present recent advances in phase-sensitive amplification technology and its application to the regeneration of phase-encoded signals. Using a combination of parametric effects in fibers and optical injection locking of lasers, it is possible to observe phase regeneration in signals with multiple levels of phase encoding.
18 Jul 2011
TL;DR: In this article, the application of phase sensitive fiber optical parametric devices for the processing and quantization of optical phase including recent experimental demonstrations is discussed, as well as their application in optical phase processing.
Abstract: We discuss the application of phase sensitive fiber optical parametric devices for the processing and quantization of optical phase including recent experimental demonstrations.