Armando Nolasco Pinto

University of Aveiro | UA · Department of Electronics, Telecommunications and Informatics

In this Letter we present a discrete modulated, continuous variables quantum key distribution implementation using two probabilistically shaped, 128-symbol, amplitude and phase shift keying constellations. At Bob's detection side, a polarization diverse, true heterodyne receiver architecture is implemented for symbol recovery. We demonstrate experi...

We present a method for optimizing the waveplate’s voltage range of an electro-optic based electrical polarization controller for qubit encoding in discrete-variable quantum key distribution (QKD). By increasing the number of used waveplates, the maximum voltage range to generate each of the states-of-polarization required by a QKD protocol can be...

In this work we present the impact of the uncertainty of the shot noise estimate on the performance of a continuous variables quantum key distribution system using a probabilistically shaped 128-APSK constellation. We demonstrate that the performance of the system is greatly degraded by the uncertainty of the shot noise estimate, with a total loss...

In this work, a fully functional polarization-encoding quantum key distribution system (QKD) is demonstrated. At the transmitter side, the polarization states are prepared using an algorithm to determine the voltages to be applied on the electronic polarization controller (EPC), to generate up to four polarization states. At the receiver, a second...

In this work we study the performance of M-symbol (M-)Amplitude and Phase Shift Keying (APSK) constellations for Continuous-Variable Quantum Key Distribution systems. Despite the gap still observed between the performance of higher order regular M-APSK constellations with binomial distribution for probabilistic shaping and the optimal performance o...

Quantum Secure Multiparty Computation (QSMC) is a technology that takes the advantage of quantum features allowing multiple parties to communicate in a secure and efficient manner while preserving their privacy. Using QSMC technology, we implement a collision warning use case in which vehicles can freely broadcast information while preserving the p...

We present a polarization diverse receiver architecture for continuous variables quantum key distribution. We demonstrate experimentally that our system is capable of reliably achieving theoretical security against collective attacks, even under very adverse random polarization drift scenarios, and is capable of functioning indefinitely without any...

We present an optimized dual-stage CPR method based on pilot symbols and a blind phase search algorithm (BPS) for M -QAM coherent optical transmission systems, targeting an efficient hardware implementation. A comprehensive optimization of the key CPR parameters is performed, including, pilot-rate, number of test phases, angle interval and moving a...

The carrier contribution factor (CCF) is used in the DC-value method to assure the minimum phase condition (MPC) at the transmitter. We analyze the impact of the CCF estimation accuracy at the receiver on the DC-value system performance. We found that the CCF estimation accuracy at the receiver should be within ±5% to exploit all advantages of the...

Discrete modulation continuous variable quantum key distribution (DM-CV-QKD) is highly considered in real implementations to avoid the complexity of Gaussian modulation (GM), which is optimum in terms of the key rate. DM-CV-QKD systems usually consider M-symbol phase shift keying (M-PSK) constellations. However, this type of constellation cannot re...

This paper reviews recent progress on different high-speed optical short- and medium-reach transmission systems. Furthermore, a comprehensive tutorial on high-performance, low-cost, and advanced optical transceiver (TRx) paradigms is presented. In this context, recent advances in high-performance digital signal processing algorithms and innovative...

Quantum random number generators (QRNGs) are currently in high demand across a large number of cryptographic applications as secure sources of true randomness. In this work, we characterize the conditions from which randomness can be extracted in a QRNG based on homodyne measurements of vacuum fluctuations by assessing the impact of experimental li...

We experimentally demonstrate for the first time the performance of the DC-Value (DC-V) phase recovery method in direct-detection optical links. It offers greater than 13% BER improvement in QPSK transmission compared to state-of-art upsampling-free methods.

Integration technology advancement has impacted the System-on-Chip (SoC) in which heterogeneous cores are supported on a single chip. Based on the huge amount of supported heterogeneous cores, efficient communication between the associated processors has to be considered at all levels of the system design to ensure global interconnection. This can...

We propose a novel method to reconstruct the optical signal phase information using direct detection. The method is suitable for minimum phase signals and it enables low complexity, low latency, and low tone power operation. Moreover, the proposed method offers low optical complexity solution for the short-reach links compared with the concurrent p...

The mismatch between the photovoltaic (PV) cells absorption and the solar irradiance on earth is one of the major limitations towards more efficient PV energy conversion. This aspect was addressed by down-shifting the solar irradiance on Earth through luminescent down-shifting layers based on lanthanide-doped surface-functionalized ionosilicas (ISs...

The oblivious transfer primitive is sufficient to implement secure multiparty computation. However, secure multiparty computation based only on classical cryptography is severely limited by the security and efficiency of the oblivious transfer implementation. We present a method to efficiently and securely generate and distribute oblivious keys by...

We assess an algorithm for polarization basis alignment for quantum communication systems considering different polarization linewidth and transmission lengths. The algorithm has an overhead below 2% and guarantees an average channel QBER below 1%.

We present a digital technique able to monitor and compensate for the mode-dependent losses (MDL) in space-division multiplexing (SDM) transmission systems. The working principle of the technique is based on the analysis of the received signal samples in the higher-order Poincaré spheres (HoPs). When an arbitrary pair of tributaries is represented...

The recent advances in coherent optical systems enable the use of efficient modulation formats, such as quadrature phase shift keying (QPSK). In this framework, we present an integrated 90° hybrid 2 × 4 coupler based on self-patternable organic–inorganic hybrid thin films fabricated using direct laser writing. The device was coupled to balanced pho...

We experimentally evaluate the performance of the adaptive Stokes polarization demultiplexing (PolDemux) algorithm over a long-haul optical link considering the propagation of 31 × 192 Gb/s channels modulated as PM- 16QAM multi-subcarrier (MSC) signals. Initially, we consider 1 × 24 Gbaud channel under test, and subsequently we assess the performan...

We evaluate the impact of optical amplifier failure on the achievable information rate (AIR) of a transmission link. We consider two scenarios to avoid link failure. First, we consider that after amplifier failure the optical signals are switched to a redundant passive optical line card which surpasses the damage amplifier. Second, we assume that t...

We propose a reduced-complexity space-demultiplexing algorithm based on higher-order Poincaré spheres (HoPs) which is modulation format agnostic, free of training sequences and robust to the local oscillator phase fluctuations and frequency o sets. The signal tributaries are space-demultiplexed by calculating and realigning the best fit plane in th...

Luminescent solar concentrators (LSCs) are luminescent waveguide layers that convert sunlight into specific wavelengths which are then guided by total internal reflection to a PV device located at the edges of the LSC. Their ability to concentrate sunlight onto small areas makes LSCs a useful complement to silicon-based PVs in a series of applicati...

We propose and experimentally validate a low complexity time-domain (TD) digital backpropagation (DBP) algorithm for fiber nonlinearity compensation, targeting an optimized hardware implementation. To counteract the coherent accumulation of numerical quantization errors between DBP steps, we propose a random step-size distribution along the optical...

Employing step-size randomization and multi-band quantization, we propose a reduced complexity time-domain (TD) digital backpropagation (DBP) and experimentally demonstrate penalty-free operation at an average number of ~ 4 bits per FIR coefficient.

We introduce a cost-effective organic-inorganic hybrid photonic integrated circuit suitable for coherent access networks and demonstrate a 3.5±0.3 dB power penalty, relatively to back-to-back, for 20 Gb/s QPSK transmission over 40 km of G.652 fiber.

The fibre-fault monitoring is a crucial network element, especially for passive optical networks. In this work is presented and demonstrated experimentally a simplified method for the optical access network monitoring, based on fibre Bragg gratings, deployed near vulnerable network locations. We experimentally demonstrated the use of this technique...

We propose a 400G frequency-hybrid superchannel solution based on three carriers, two edge PM-16QAM and a central PM-64QAM carrier, compatible with the 62.5 GHz grid slot (spectral efficiency of 6.4 b/s/Hz). The proposed superchannel is experimentally assessed in long-haul transmission by co-propagation with other 8 similar superchannels. The optim...

We numerically investigate the polarization-mode dispersion (PMD) tolerance of Stokes space based polarization-demultiplexing (SSPolDemux) algorithms in optical transmission supported by coherent detection and digital signal processing. The PMD tolerance is evaluated as function of the ratio differential group delay over symbol period, allowing to...

We propose a space-demultiplexing algorithm based on signal analysis in higher-order Poincaré spheres for optical transmission systems supported by space-division multiplexing. This algorithm is modulation format agnostic and does not require training sequences. We show that any arbitrary pair of tributaries signals can be represented in a higher-o...

We develop a simplified high-order multi-span Volterra series transfer function (SH-MS-VSTF), basing our derivation on the well-known third-order Volterra series transfer function (VSTF). We notice that when applying an approach based on a recursive method and considering the phased-array factor, the order of the expression for the transfer functio...

The impact of optical amplification on the achievable information rate (AIR) is evaluated, considering continuous and discrete modulation formats. The theoretical model for the AIR considers the optical amplification noise, the nonlinear optical noise, and the coherent receiver shot and thermal noise sources. Two different scenarios for the AIR are...

We experimentally demonstrate a flexible coherent UDWDM system with support to optical-wireless links and adaptive DP-QPSK/DP-16QAM modulation, enabled by Stokes-based polarization-demultiplexing. The system is shown to be resilient to dynamic power ranges of >12 dB.

We experimentally demonstrate a PM-16QAM/64QAM triple-carrier 400G superchannel compatible with the 62.5GHz grid. The optimum power ratio between carriers is analytically determined using the EGN model, enabling a maximum reach of 1700km.

We experimentally demonstrate a reduced complexity time-domain CD equalizer in a dual-carrier 400G PM-16QAM system, yielding hardware savings of over 99% in terms of multipliers, and a latency reduction of ∼80% over standard frequency-domain CD equalization.

Using digital backpropagation (DBP) based on the split step Fourier method (SSFM) aided by a memory polynomial (MP) model, we demonstrate an improved DBP approach for fiber nonlinearity compensation. The proposed technique (DBP-SSFM&MP) is numerically validated and its performance and complexity are compared against the benchmark DBP-SSFM, consider...

We demonstrate the first reconfigurable real-time receiver DSP in a flexible heterogeneous UDWDM system for coherent PON applying different modulation formats. The evaluation reports the ODN power budget for multiple UDWDM configurations using QPSK, 8PSK and 8QAM signals. http://ieeexplore.ieee.org/document/7767718/

We propose a novel and efficient multiplierless finite-impulse response (FIR)-based filter architecture for chromatic dispersion equalization (CDE) in coherent optical communication systems. After quantizing the FIR coefficients, we take advantage of the high multiplicity of their real and imaginary parts, employing the distributive property of mul...

We report an optimized hardware scheme for carrier frequency and phase recovery algorithms based on Mth-order power schemes for flexible intradyne coherent receivers. The phase recovery is based on the traditional Viterbi & Viterbi algorithm with a feedforward architecture, which requires an Mth-order power nonlinear operation. The output of such o...

A non-intrusive technique to continuously control random polarization rotations for quantum communications is proposed. It allows an automatic control of the random polarization rotations that photons suffer during their propagation inside standard fibers, without the use of additional classical signals and hardware. The polarization control method...

We report the fabrication and the structural and optical characterization of transparent spin coated films (average thickness values of 4.9 ± 0.1 µm) of organic–inorganic hybrids (di-ureasils) doped with the Disperse Red 1 (DR1) chromophore. The refractive index was measured by prism coupling and spectroscopic ellipsometry revealing that the inclus...

Random polarization rotations caused by residual fiber birefringence is an important physical effect in optical coherent systems employing polarization-division multiplexing. The specificity of the large penalties induced by polarization-related impairments make polarization-dedicated equalization subsystems mandatory for the design of flexible coh...

We report our recent advances in the implementation of very high-speed optical channels (targeting 400 Gbps and 1 Tbit) based on multi-carrier super-channels supported by intense digital signal processing. We present results on modulation format agnostic polarization demultiplexing, computationally efficient chromatic dispersion equalization, and d...

The next generation of optical networks requires the development of optical technology that supports high bandwidth, such as the coherent systems. The coherent detection allows the in-phase and quadrature components of a QPSK signal to be extracted as a result of the interference with a local oscillator. An integrated optics flexible 90° hybrid cou...

In this work, we experimentally implement an adaptive polarization demultiplexing (PolDemux) technique based on the representation of the state of polarization (SOP) of the signal in the Stokes space in bidirectional ultra-dense wavelength-division-multiplexed (U-DWDM) optical metro networks. BER measurement is used to assess the quality of DP-QPSK...

Optical systems are recognized to be an important tool for structural health monitoring, especially for real time safety assessment, due to simplified system confi guration and low cost when compared to regular systems, namely electrical systems. This work aims to present a case study on structural health monitoring focused on reliability assessmen...

We report a hardware optimization for frequency and phase recovery algorithms based on Mth-order power schemes, evaluating the accuracy of the reported architecture with an 8-bit DSP in real-time for a 1.25 and 2.5 Gb/s DQPSK signal.

Air humidity is a parameter with relevant interest to a wide variety of areas, both in industry or in domestic processes. Due to the growing demand on air humidity monitors, especially relative humidity, the development of sensors to assess this parameter has been increasing. Moreover, in the last years, the optical fibre based technology has been...

Optical superchannels and digital nonlinear mitigation are key technology options to be considered for the deployment of next-generation optical 400G transmission systems. In this paper, we experimentally assess the performance and complexity of multicarrier digital backpropagation (DBP) for dual- and triple-carrier 400G superchannels based on pola...

We experimentally assess the performance versus complexity tradeoff of advanced split-step and Volterra-based digital backpropagation (DBP) techniques, applied to a WDM (75 GHz flexigrid) ultra-long-haul (ULH) transmission system composed of 5 dual-carrier PM-16QAM 400G superchannels. Using the recently proposed weighted Volterra series nonlinear e...

We demonstrate experimentally the feasibility of a two-state quantum bit commitment protocol, which is both concealing and partially binding, assuming technological limitations. The security of this protocol is based on the lack of long-term stable quantum memories. We use a polarization-encoding scheme and optical fiber as a quantum channel. The m...

We experimentally characterize a bidirectional 2.5 Gb/s UDWDM-PON system based on Nyquist shaped DQPSK with digital signal processing in real time. The optical distribution network power budget of this system is evaluated and in coexistence of UDWDM channels with upstream TWDM-PON and RF video overlay signals, a set of optimum parameters and their...

We experimentally analyze an adaptive polarization-demultiplexing (PolDemux) technique based on the representation of the state of polarization of the signal in the Stokes space. The performance and convergence speed of the Stokes PolDemux are compared with the constant modulus algorithm, for dual polarization QPSK and 16QAM modulation formats in a...

By deriving the physical model of the system, which includes definitions of both state variables and measurement equations, we apply an extended Kalman filter to Stokes space based polarization demultiplexing for complex-modulated signals. The convergence ratio, tracking, computational complexity, and system performance of this method are investiga...

We analyze the capital expenditures (CapEx) and operational expenditures (OpEx) related to the power consumption and footprint requirements of fixed and flexible node architectures in a multiperiod scenario and under different traffic requirements. We consider fixed architectures based on muxponders, and nonblocking and partial nonblocking flexible...

We propose an in-line wavelength selective core switch for multicore fiber (MCF) transmission systems, based on the acousto-optic effect. A theoretical model addressing the interaction between flexural acoustic waves and the optical signal in MCFs is developed. We show that an optical signal propagating in a particular core can be switched to any o...

We report a field-trial of bidirectional coherent Nyquist UDWDM-PON using off-the-shelf real-time FPGA-based transceivers, coexisting with GPON, RF Video and NG-PON2. A sensitivity of -44.5 dBm is achieved for 64×2.5 Gb/s DQPSK, with a 17 dB dynamic power range for US channels.

We experimentally demonstrate a parallel split-step Fourier method in an ultra-long-haul dual-carrier 400G transmission system. For a reach enhancement of 500-800 km over linear equalization, we demonstrate a 5× reduction of the step-size when compared to the standard split-step Fourier method.

We experimentally assess the performance of dual-and triple-carrier 5⇥400G superchannels (5.33 b/s/Hz) for ultra-long-haul transmission (>6000 km). Using digital backpropagation with a coupled equations approach, we demonstrate an extended propagation reach of up to 1600 km.