Victor Parahyba - Academia.edu (original) (raw)

Papers by Victor Parahyba

ACS Applied Electronic Materials

Chemistry of Materials

After the use of nanocrystals as light down-converters, infrared sensing appears to be one of the... more After the use of nanocrystals as light down-converters, infrared sensing appears to be one of the first market applications where they can be used while being both electrically and optically active. Over recent years, tremendous progress has been achieved, leading to an apparent rise in the technological readiness level (TRL). So far, the efforts have been focused on PbS nanocrystals for operation in the near-infrared. Here, we focus on HgTe since its narrower band gap offers more flexibility to explore the extended shortwave and mid-wave infrared. We report a photoconductive strategy fort the design of short wave infrared focal plane array with enhanced image quality. An important aspect often swept under the rug at an early stage is the material stability. It appears that HgTe remains mostly unaffected by oxidation under air operation. The evaporation of Hg, a potentially dramatic aging process, only occurs at temperatures far beyond the focal plane array's standard working temperature. The main bottleneck appears to be the particle sintering resulting from joule heating of focal plane array. This suggests that a cooling system is required, with a first role of preventing the material from sintering even before targeting dark current reduction.

Nanoscale

Image (left) acquired using a camera which active layer is a photoconductive layer fabricated fro... more Image (left) acquired using a camera which active layer is a photoconductive layer fabricated from a HgTe nanocrystal film (schematic on right).

39th European Conference and Exhibition on Optical Communication (ECOC 2013), 2013

We investigated the performance of a 1.12-Tb/s (5×224-Gb/s PDM-16QAM) superchannel with 6-b/s/Hz,... more We investigated the performance of a 1.12-Tb/s (5×224-Gb/s PDM-16QAM) superchannel with 6-b/s/Hz, using optical prefiltering, over hybrid LongLine-SSMF link with hybrid Raman-EDFA amplification and cascaded 175-GHz ROADMs. A maximum reach of 1000-km with 10-ROADM passes was obtained employing nonlinear compensation.

SBrT 2013, 2013

High order modulation nonlinear effects has been appointed as the main limitation in coherent opt... more High order modulation nonlinear effects has been appointed as the main limitation in coherent optical fiber transmission. Many different approaches has been investigated to cope with nonlinear effects in optical systems and the most studied method for coherent systems is the digital backpropagation algorithm. MLSE methods have also been effective in combating nonlinear impairments; however it has only been implemented for 112 Gb/s QPSK systems. In this paper, we perform, for the first time, a maximum likelihood sequence estimator (MLSE) in the context of an experimental PDM-16QAM transmission and compare the result with Digital Backpropagation equalization. Also, the use of a combination of both methods is proposed, which increases the distance reached in over 40%.

Revista Ciências do …, 2010

RESUMO: Este estudo tem por objetivo criar um mapa de risco para a poluição sonora a que são expo... more RESUMO: Este estudo tem por objetivo criar um mapa de risco para a poluição sonora a que são expostos diariamente os alunos e trabalhadores do campus principal da Unicamp através da análise dos níveis de ruído em locais com grande movimentação de pessoas, ...

Applied Physics Letters

Thanks to their remarkable spectral tunability across the entire infrared range, HgTe nanocrystal... more Thanks to their remarkable spectral tunability across the entire infrared range, HgTe nanocrystals present a unique platform for designing infrared optoelectronic devices. While in recent years most of the significant advances in this domain have been made on devices at the single-pixel level, there is a growing trend toward exploring the potential of this material for imaging applications. However, until recently, focal plane arrays based on HgTe colloidal nanocrystals have been limited to the photoconductive mode, which is inherently associated with a large dark current. In this work, we demonstrate a diode stack compatible with a readout integrated circuit whose back-end processing has been optimized to ensure compatibility with a complete diode stack deposition. The diode design is also optimized to generate a Fabry–Pérot cavity in which 50% of the light is effectively absorbed at the band edge. Finally, taking benefit from the full video graphics array format, high-resolution i...

Advanced Optical Materials, 2021

Nanocrystals (NCs) have reached a high level of maturity, enabling their integration into optoele... more Nanocrystals (NCs) have reached a high level of maturity, enabling their integration into optoelectronic devices. The next challenge is the combination of several types of devices into one complex system to achieve better on‐chip integration. Here, an all‐HgTe‐NC active imaging setup operating in the short‐wave infrared (IR) is focused on. First, the design of an optimized IR light‐emitting diode (LED) is focused on. It is shown that a halide technology processing enables an increase of the electroluminescence signal by a factor of 3, while preserving a low turn‐on voltage and a high brightness (3 W sr−1 m−2). Then the degradation mechanism of this LED under continuous operation is unveiled and a shift from band edge to trap emission is shown. This degradation process can be strongly reduced thanks to the encapsulation and the thermal control of the LED. Lastly, the IR emission of the LED is imaged using a focal plane array whose active layer is also made of HgTe NCs, paving the way for all‐NC‐based active imaging setups.

Optical Communications, 2018

This chapter presents an overview of modeling and mitigation of nonlinear effects on coherent opt... more This chapter presents an overview of modeling and mitigation of nonlinear effects on coherent optical systems. The Gaussian Noise (GN) is presented as an efficient method to analyze the nonlinear propagation in an uncompensated link and used to estimate the system performance. In order to compensate for the nonlinear impairments, four digital techniques were investigated: Digital Back-Propagation (DBP), DBP with coupled equations, Volterra series, and Maximum Likelihood Sequence Estimator (MLSE). Different scenarios were used to validate the algorithms. Finally, a nonlinear estimation algorithm based on Steepest Descent Algorithm (SDA) is shown and experimentally validated in an unrepeatered optical system.

A evolucao dos sistemas opticos coerentes permitiu a utilizacao de formatos de modulacao que carr... more A evolucao dos sistemas opticos coerentes permitiu a utilizacao de formatos de modulacao que carregam informacao atraves da fase, amplitude e polarizacao do sinal optico. Ao mesmo tempo, o desenvolvimento da eletronica permite que esses sinais, agora disponiveis no dominio digital, possam ser tratados por algoritmos de processamento de forma a compensar os principais efeitos responsaveis por deteriorar o sinal ao longo do enlace de transmissao. Dentre as distorcoes tratadas estao a dispersao cromatica e a dispersao de modo de polarizacao, cujas compensacoes sao vitais para sistemas acima de 40 Gb/s. A sincronia temporal e a recuperacao de portadora tambem e realizada no dominio digital, tornando desnecessario o controle temporal dos lasers utilizados na transmissao e recepcao, barateando os custos e propiciando a disseminacao de sistemas com taxas mais elevadas. O proximo obstaculo na obtencao de maiores capacidades se torna entao a compensacao dos chamados efeitos nao lineares da fibra optica. Nesta dissertacao, os conceitos de transmissao coerente digital e os principais algoritmos para a recepcao e recuperacao de sinal sao apresentados. A partir dai, discutimos as origens e consequencias dos efeitos nao lineares que deterioram o sinal transmitido e impedem a elevacao da potencia de lancamento na fibra optica. Duas solucoes para o problema sao apresentadas e discutidas: o algoritmo de Retropropagacao Digital (DBP) e o estimador de sequencia de maxima verossimilhanca (MLSE), alem de variacoes que possam melhorar o seu desempenho. Os resultados de simulacoes e experimentos sao apresentados e demonstram a eficacia dos metodos discutidos. Em uma transmissao experimental DP-16QAM com taxa de 224 Gb/s foi possivel perceber um ganho em distância de mais de duas vezes com a utilizacao do DBP, em comparacao com a equalizacao puramente linear, enquanto que a combinacao dos dois metodos proporcional quase tres vezes o alcance original. Por fim, realizamos um estudo da complexidade do algoritmo DBP em termos de multiplicacoes complexas e uma estimativa de ocupacao de area em textit{chip} que o modulo de compensacao de nao linearidade teria. Os resultados mostram a importância que a compensacao de nao linearidades tera em sistemas opticos de altas taxas no futuro e o grande desafio nessa area de estudo que e a reducao da complexidade das solucoes. Abstract

Proceedings of the nanoGe Fall Meeting 2021, 2021

Anais de XXX Simpósio Brasileiro de Telecomunicações, 2012

High order modulation nonlinear effects has been appointed as the main limitation in coherent opt... more High order modulation nonlinear effects has been appointed as the main limitation in coherent optical fiber transmission. Digital back-propagation algorithms are one of the current studied methods to cope with such impairment and extend the systems maximum reach. In this article, we analyzed the digital back-propagation performance in a 224 Gb/s dual polarization 16QAM optical coherent system. It was observed a 35% increase in maximum reached distance and an OSNR gain of 2.6 dB. In order to reduce the huge required computational complexity, an modified back-propagation algorithm is analyzed.

Anais de XXIX Simpósio Brasileiro de Telecomunicações, 2011

Fundação CPqD, 2-FEEC Unicamp Resumo-Imperfeições no front-end do receptor coerente deterioram a ... more Fundação CPqD, 2-FEEC Unicamp Resumo-Imperfeições no front-end do receptor coerente deterioram a qualidade do sistema de transmissão óptico. As componentes do sinal perdem sua característica de ortogonalidade, provocando interferência intrasimbólica. Este artigo propõe e compara métodos para a aplicação em tempo real dos procedimentos de ortonormalização de Gram-Schmidt e de Löwdin. A avaliação de desempenho dos métodos é feita segundo quatro parâmetros: eficiência da ortogonalização, desequilíbrio de potência entre as componentes, BER estimada e complexidade computacional.

IEEE Photonics Technology Letters, 2016

We demonstrate unrepeatered transmission of 10 × 400-Gb/s PM-16QAM Nyquist wavelength-division mu... more We demonstrate unrepeatered transmission of 10 × 400-Gb/s PM-16QAM Nyquist wavelength-division multiplexing (WDM) dual-carrier superchannels (75-GHz flexigrid) at the SE = 5.33 b/s/Hz, where each superchannel is coherently detected by a single wideband receiver. A 350-km transmission is achieved by using optimized amplification map to efficiently design remote optically pumped amplifier and hybrid amplifiers. Additional digital domain nonlinear compensation allows to increase the transmission distance up to 370 km.

2015 European Conference on Optical Communication (ECOC), 2015

Approaches to the diagnosis and treatment of various kinds of low back pain are described in this... more Approaches to the diagnosis and treatment of various kinds of low back pain are described in this paper. As the center and axis of the human body, the low back has to bear a variety of heavy loads during everyday movements, and low back pain has been found to be the most common of various symptoms complained of by the Japanese public in a survey by the Japanese Ministry of Health and Welfare. Thus, correct diagnosis and treatment of the underlying cause of low back pain is essential to maintaining the quality of life of many Japanese. Low back pain caused by fragility fractures in osteoporosis patients has been found to have the most significant impact on mortality among the various kinds of fractures that occur in the elderly. It is concluded that low back pain, a disease of the axis of human body, has a critical influence not only on quality of life, but on the life of the elderly in an aged society.

2015 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC), 2015

We infer, by computer simulations, practical values of the overlap length for frequency-domain ch... more We infer, by computer simulations, practical values of the overlap length for frequency-domain chromatic dispersion compensation in long and ultra-long-haul coherent optical systems. The overlap length has a direct impact on computational complexity and the receive-side DSP power consumption. The NRZ, RZ, and Nyquist-shaped signals are investigated. The presented results may be used as guidelines for trading off OSNR margin and computational complexity. In a sufficiently high OSNR scenario, these trade-offs may reduce computational complexity by 10-25%, depending on the particular filter implementation.

2015 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC), 2015

We analyze the performance limits of the digital back-propagation (DBP) algorithm implemented in ... more We analyze the performance limits of the digital back-propagation (DBP) algorithm implemented in application specific integrated circuits (ASIC). The proposed hardware implementation, jointly with a set of other digital signal processing (DSP) blocks, was experimentally evaluated by processing a 32 GBd PDM-16QAM signal. In the transmitter side, it is discussed the linear filters complexity for Nyquist spectral shaping and the trade-off between number of taps and filter roll-off. Then, at the receiver, linear filters and nonlinear compensators are used to equalize chromatic dispersion (CD) and nonlinear distortions, respectively. These stages characterize the DBP block, which is able to enhance the transmission reach and the optimum launch power of the optical system. Transmission performance is optimized for different DBP implementations, considering two CMOS technology nodes: 16 nm and 28 nm. The DBP complexity is evaluated in terms of the required die size and in terms of number of the DBP stages and fiber span-lengths. For a target gain of 35% (in comparison with the CD-only compensation) on the transmission reach, the required DBP chip size is around 1.6 mm x 1.6 mm using 16 nm CMOS technology. The chip area of the nonlinear stage is only 16% larger than the linear stage.

Electronics Letters, 2015

The trade-off between transmission performance and hardware implementation in application-specifi... more The trade-off between transmission performance and hardware implementation in application-specific integrated circuits of digital backpropagation (DBP) in coherent 32 GBd polarisation-division multiplexing 16 quadrature amplitude modulation is analysed. The reach is optimised for different DBP implementations under constraints of 16 and 28 nm complementary metal–oxide–semiconductor (CMOS) technology digital signal processing (DSP) area.

Optical Fiber Communication Conference, 2014

We demonstrated the transmission of 3x1.12-Tb/s superchannels (5x224-Gb/s PDM-16QAM) in 162.5-GHz... more We demonstrated the transmission of 3x1.12-Tb/s superchannels (5x224-Gb/s PDM-16QAM) in 162.5-GHz flexible-grid, 6.5-b/s/Hz SE, using only optical spectral shaping, over SSMF-EDFA link. A maximum reach of 600-km with 3-ROADM passes was obtained employing nonlinear compensation.

ACS Applied Electronic Materials

Chemistry of Materials

After the use of nanocrystals as light down-converters, infrared sensing appears to be one of the... more After the use of nanocrystals as light down-converters, infrared sensing appears to be one of the first market applications where they can be used while being both electrically and optically active. Over recent years, tremendous progress has been achieved, leading to an apparent rise in the technological readiness level (TRL). So far, the efforts have been focused on PbS nanocrystals for operation in the near-infrared. Here, we focus on HgTe since its narrower band gap offers more flexibility to explore the extended shortwave and mid-wave infrared. We report a photoconductive strategy fort the design of short wave infrared focal plane array with enhanced image quality. An important aspect often swept under the rug at an early stage is the material stability. It appears that HgTe remains mostly unaffected by oxidation under air operation. The evaporation of Hg, a potentially dramatic aging process, only occurs at temperatures far beyond the focal plane array's standard working temperature. The main bottleneck appears to be the particle sintering resulting from joule heating of focal plane array. This suggests that a cooling system is required, with a first role of preventing the material from sintering even before targeting dark current reduction.

Nanoscale

Image (left) acquired using a camera which active layer is a photoconductive layer fabricated fro... more Image (left) acquired using a camera which active layer is a photoconductive layer fabricated from a HgTe nanocrystal film (schematic on right).

39th European Conference and Exhibition on Optical Communication (ECOC 2013), 2013

We investigated the performance of a 1.12-Tb/s (5×224-Gb/s PDM-16QAM) superchannel with 6-b/s/Hz,... more We investigated the performance of a 1.12-Tb/s (5×224-Gb/s PDM-16QAM) superchannel with 6-b/s/Hz, using optical prefiltering, over hybrid LongLine-SSMF link with hybrid Raman-EDFA amplification and cascaded 175-GHz ROADMs. A maximum reach of 1000-km with 10-ROADM passes was obtained employing nonlinear compensation.

SBrT 2013, 2013

High order modulation nonlinear effects has been appointed as the main limitation in coherent opt... more High order modulation nonlinear effects has been appointed as the main limitation in coherent optical fiber transmission. Many different approaches has been investigated to cope with nonlinear effects in optical systems and the most studied method for coherent systems is the digital backpropagation algorithm. MLSE methods have also been effective in combating nonlinear impairments; however it has only been implemented for 112 Gb/s QPSK systems. In this paper, we perform, for the first time, a maximum likelihood sequence estimator (MLSE) in the context of an experimental PDM-16QAM transmission and compare the result with Digital Backpropagation equalization. Also, the use of a combination of both methods is proposed, which increases the distance reached in over 40%.

Revista Ciências do …, 2010

RESUMO: Este estudo tem por objetivo criar um mapa de risco para a poluição sonora a que são expo... more RESUMO: Este estudo tem por objetivo criar um mapa de risco para a poluição sonora a que são expostos diariamente os alunos e trabalhadores do campus principal da Unicamp através da análise dos níveis de ruído em locais com grande movimentação de pessoas, ...

Applied Physics Letters

Thanks to their remarkable spectral tunability across the entire infrared range, HgTe nanocrystal... more Thanks to their remarkable spectral tunability across the entire infrared range, HgTe nanocrystals present a unique platform for designing infrared optoelectronic devices. While in recent years most of the significant advances in this domain have been made on devices at the single-pixel level, there is a growing trend toward exploring the potential of this material for imaging applications. However, until recently, focal plane arrays based on HgTe colloidal nanocrystals have been limited to the photoconductive mode, which is inherently associated with a large dark current. In this work, we demonstrate a diode stack compatible with a readout integrated circuit whose back-end processing has been optimized to ensure compatibility with a complete diode stack deposition. The diode design is also optimized to generate a Fabry–Pérot cavity in which 50% of the light is effectively absorbed at the band edge. Finally, taking benefit from the full video graphics array format, high-resolution i...

Advanced Optical Materials, 2021

Nanocrystals (NCs) have reached a high level of maturity, enabling their integration into optoele... more Nanocrystals (NCs) have reached a high level of maturity, enabling their integration into optoelectronic devices. The next challenge is the combination of several types of devices into one complex system to achieve better on‐chip integration. Here, an all‐HgTe‐NC active imaging setup operating in the short‐wave infrared (IR) is focused on. First, the design of an optimized IR light‐emitting diode (LED) is focused on. It is shown that a halide technology processing enables an increase of the electroluminescence signal by a factor of 3, while preserving a low turn‐on voltage and a high brightness (3 W sr−1 m−2). Then the degradation mechanism of this LED under continuous operation is unveiled and a shift from band edge to trap emission is shown. This degradation process can be strongly reduced thanks to the encapsulation and the thermal control of the LED. Lastly, the IR emission of the LED is imaged using a focal plane array whose active layer is also made of HgTe NCs, paving the way for all‐NC‐based active imaging setups.

Optical Communications, 2018

This chapter presents an overview of modeling and mitigation of nonlinear effects on coherent opt... more This chapter presents an overview of modeling and mitigation of nonlinear effects on coherent optical systems. The Gaussian Noise (GN) is presented as an efficient method to analyze the nonlinear propagation in an uncompensated link and used to estimate the system performance. In order to compensate for the nonlinear impairments, four digital techniques were investigated: Digital Back-Propagation (DBP), DBP with coupled equations, Volterra series, and Maximum Likelihood Sequence Estimator (MLSE). Different scenarios were used to validate the algorithms. Finally, a nonlinear estimation algorithm based on Steepest Descent Algorithm (SDA) is shown and experimentally validated in an unrepeatered optical system.

A evolucao dos sistemas opticos coerentes permitiu a utilizacao de formatos de modulacao que carr... more A evolucao dos sistemas opticos coerentes permitiu a utilizacao de formatos de modulacao que carregam informacao atraves da fase, amplitude e polarizacao do sinal optico. Ao mesmo tempo, o desenvolvimento da eletronica permite que esses sinais, agora disponiveis no dominio digital, possam ser tratados por algoritmos de processamento de forma a compensar os principais efeitos responsaveis por deteriorar o sinal ao longo do enlace de transmissao. Dentre as distorcoes tratadas estao a dispersao cromatica e a dispersao de modo de polarizacao, cujas compensacoes sao vitais para sistemas acima de 40 Gb/s. A sincronia temporal e a recuperacao de portadora tambem e realizada no dominio digital, tornando desnecessario o controle temporal dos lasers utilizados na transmissao e recepcao, barateando os custos e propiciando a disseminacao de sistemas com taxas mais elevadas. O proximo obstaculo na obtencao de maiores capacidades se torna entao a compensacao dos chamados efeitos nao lineares da fibra optica. Nesta dissertacao, os conceitos de transmissao coerente digital e os principais algoritmos para a recepcao e recuperacao de sinal sao apresentados. A partir dai, discutimos as origens e consequencias dos efeitos nao lineares que deterioram o sinal transmitido e impedem a elevacao da potencia de lancamento na fibra optica. Duas solucoes para o problema sao apresentadas e discutidas: o algoritmo de Retropropagacao Digital (DBP) e o estimador de sequencia de maxima verossimilhanca (MLSE), alem de variacoes que possam melhorar o seu desempenho. Os resultados de simulacoes e experimentos sao apresentados e demonstram a eficacia dos metodos discutidos. Em uma transmissao experimental DP-16QAM com taxa de 224 Gb/s foi possivel perceber um ganho em distância de mais de duas vezes com a utilizacao do DBP, em comparacao com a equalizacao puramente linear, enquanto que a combinacao dos dois metodos proporcional quase tres vezes o alcance original. Por fim, realizamos um estudo da complexidade do algoritmo DBP em termos de multiplicacoes complexas e uma estimativa de ocupacao de area em textit{chip} que o modulo de compensacao de nao linearidade teria. Os resultados mostram a importância que a compensacao de nao linearidades tera em sistemas opticos de altas taxas no futuro e o grande desafio nessa area de estudo que e a reducao da complexidade das solucoes. Abstract

Proceedings of the nanoGe Fall Meeting 2021, 2021

Anais de XXX Simpósio Brasileiro de Telecomunicações, 2012

High order modulation nonlinear effects has been appointed as the main limitation in coherent opt... more High order modulation nonlinear effects has been appointed as the main limitation in coherent optical fiber transmission. Digital back-propagation algorithms are one of the current studied methods to cope with such impairment and extend the systems maximum reach. In this article, we analyzed the digital back-propagation performance in a 224 Gb/s dual polarization 16QAM optical coherent system. It was observed a 35% increase in maximum reached distance and an OSNR gain of 2.6 dB. In order to reduce the huge required computational complexity, an modified back-propagation algorithm is analyzed.

Anais de XXIX Simpósio Brasileiro de Telecomunicações, 2011

Fundação CPqD, 2-FEEC Unicamp Resumo-Imperfeições no front-end do receptor coerente deterioram a ... more Fundação CPqD, 2-FEEC Unicamp Resumo-Imperfeições no front-end do receptor coerente deterioram a qualidade do sistema de transmissão óptico. As componentes do sinal perdem sua característica de ortogonalidade, provocando interferência intrasimbólica. Este artigo propõe e compara métodos para a aplicação em tempo real dos procedimentos de ortonormalização de Gram-Schmidt e de Löwdin. A avaliação de desempenho dos métodos é feita segundo quatro parâmetros: eficiência da ortogonalização, desequilíbrio de potência entre as componentes, BER estimada e complexidade computacional.

IEEE Photonics Technology Letters, 2016

We demonstrate unrepeatered transmission of 10 × 400-Gb/s PM-16QAM Nyquist wavelength-division mu... more We demonstrate unrepeatered transmission of 10 × 400-Gb/s PM-16QAM Nyquist wavelength-division multiplexing (WDM) dual-carrier superchannels (75-GHz flexigrid) at the SE = 5.33 b/s/Hz, where each superchannel is coherently detected by a single wideband receiver. A 350-km transmission is achieved by using optimized amplification map to efficiently design remote optically pumped amplifier and hybrid amplifiers. Additional digital domain nonlinear compensation allows to increase the transmission distance up to 370 km.

2015 European Conference on Optical Communication (ECOC), 2015

Approaches to the diagnosis and treatment of various kinds of low back pain are described in this... more Approaches to the diagnosis and treatment of various kinds of low back pain are described in this paper. As the center and axis of the human body, the low back has to bear a variety of heavy loads during everyday movements, and low back pain has been found to be the most common of various symptoms complained of by the Japanese public in a survey by the Japanese Ministry of Health and Welfare. Thus, correct diagnosis and treatment of the underlying cause of low back pain is essential to maintaining the quality of life of many Japanese. Low back pain caused by fragility fractures in osteoporosis patients has been found to have the most significant impact on mortality among the various kinds of fractures that occur in the elderly. It is concluded that low back pain, a disease of the axis of human body, has a critical influence not only on quality of life, but on the life of the elderly in an aged society.

2015 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC), 2015

We infer, by computer simulations, practical values of the overlap length for frequency-domain ch... more We infer, by computer simulations, practical values of the overlap length for frequency-domain chromatic dispersion compensation in long and ultra-long-haul coherent optical systems. The overlap length has a direct impact on computational complexity and the receive-side DSP power consumption. The NRZ, RZ, and Nyquist-shaped signals are investigated. The presented results may be used as guidelines for trading off OSNR margin and computational complexity. In a sufficiently high OSNR scenario, these trade-offs may reduce computational complexity by 10-25%, depending on the particular filter implementation.

2015 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC), 2015

We analyze the performance limits of the digital back-propagation (DBP) algorithm implemented in ... more We analyze the performance limits of the digital back-propagation (DBP) algorithm implemented in application specific integrated circuits (ASIC). The proposed hardware implementation, jointly with a set of other digital signal processing (DSP) blocks, was experimentally evaluated by processing a 32 GBd PDM-16QAM signal. In the transmitter side, it is discussed the linear filters complexity for Nyquist spectral shaping and the trade-off between number of taps and filter roll-off. Then, at the receiver, linear filters and nonlinear compensators are used to equalize chromatic dispersion (CD) and nonlinear distortions, respectively. These stages characterize the DBP block, which is able to enhance the transmission reach and the optimum launch power of the optical system. Transmission performance is optimized for different DBP implementations, considering two CMOS technology nodes: 16 nm and 28 nm. The DBP complexity is evaluated in terms of the required die size and in terms of number of the DBP stages and fiber span-lengths. For a target gain of 35% (in comparison with the CD-only compensation) on the transmission reach, the required DBP chip size is around 1.6 mm x 1.6 mm using 16 nm CMOS technology. The chip area of the nonlinear stage is only 16% larger than the linear stage.

Electronics Letters, 2015

The trade-off between transmission performance and hardware implementation in application-specifi... more The trade-off between transmission performance and hardware implementation in application-specific integrated circuits of digital backpropagation (DBP) in coherent 32 GBd polarisation-division multiplexing 16 quadrature amplitude modulation is analysed. The reach is optimised for different DBP implementations under constraints of 16 and 28 nm complementary metal–oxide–semiconductor (CMOS) technology digital signal processing (DSP) area.

Optical Fiber Communication Conference, 2014

We demonstrated the transmission of 3x1.12-Tb/s superchannels (5x224-Gb/s PDM-16QAM) in 162.5-GHz... more We demonstrated the transmission of 3x1.12-Tb/s superchannels (5x224-Gb/s PDM-16QAM) in 162.5-GHz flexible-grid, 6.5-b/s/Hz SE, using only optical spectral shaping, over SSMF-EDFA link. A maximum reach of 600-km with 3-ROADM passes was obtained employing nonlinear compensation.