Today, we are evident to the revolution of the automotive industry and its demand for high bandwi... more Today, we are evident to the revolution of the automotive industry and its demand for high bandwidth sensor fusion. Multiple high bandwidth sensors are connected, generating tremendous amount of data to be transferred in real-time in harsh environment, i.e., multi-gigabit intra-vehicle networks. Plastic optical fiber (POF) is an attractive medium for these multi-gigabit intra-vehicle networks due to its inherent EM compatibility, galvanic isolation, low weight, high tolerance to mechanical vibrations, low bending loss, and easy handling. However, commercial off-the-shelf PMMA based POFs are bandwidth-length product limited. Here, we suggest increasing the spectral efficiency using spatial-division multiplexing (SDM). In this article, we have experimentally demonstrated a low cost and eye-safe 3 × 3 multiple-input multiple-output (MIMO) SDM system over a 15 meters multicore (MC) POF using commercial optical components, e.g., RC-LEDs and Si-PIN photodiodes. A 3 × 1 spot-based cores coupler spatial multiplexer was developed to couple the optical components with the MC-POF. This system achieved raw data rates of 1.5 Gb/s and 2.4 Gb/s using offline-processed MIMO equalization. The proposed system enables a flexible and scalable optical MIMO system that can meet the requirements of the automotive industry.
Pre-distortion for an optical transmitter modeled with complex frequency selective nonlinearity a... more Pre-distortion for an optical transmitter modeled with complex frequency selective nonlinearity applicable to different system architecture, based on recurrent neural network is proposed. Several architectures are compared and above 20dB performance gain is presented.
A method for reducing the complexity of estimating multiple timing offset in time interleaved ana... more A method for reducing the complexity of estimating multiple timing offset in time interleaved analog to digital converter based on Fourier series decomposition is proposed. The timing offset of different slices of the time interleaved analog to digital converter can be understood as points on a curve, which represents the timing offset per slice. Thus, the estimation of the timing offset can also be achieved by fitting of the timing-offset-curve. The timing offset curve can be represented by a kernel regression coefficient which are orthonormal on a limited set, thus replacing the estimation of timing offset per slice with the estimation of the regression kernel coefficients. In this paper, the idea of estimating kernel coefficients by using Fourier series analysis is presented and analyzed. When the timing offset of different slices are highly correlated, it is shown that an improvement of 3 dB can be achieved with ∼75% reduction in complexity, 6 dB improvement with ∼60% reduction and 10 dB with ∼40% reduction in respect to similar linear methods.
We propose a method for stealthy, covert, fiber-optic communication. In this method, the power of... more We propose a method for stealthy, covert, fiber-optic communication. In this method, the power of the transmitted signal is spread and lowered below the noise level both in time as well as in frequency domains which makes the signal “invisible”. The method is also efficient in jamming avoidance.
2017 European Conference on Optical Communication (ECOC), 2017
Encryption and steganography of the physical layer are experimentally demonstrated. We show a coh... more Encryption and steganography of the physical layer are experimentally demonstrated. We show a coherent stealthy transmission of 16 Gbps under negative −15 dB OSNR with pre-FEC BER of 1e-3, co-transmitted with public channel.
... ROTEM AND SADOT: EFFECT OF THERMAL CHIRP ON INTERFEROMETRIC HOMODYNE AND HETERODYNE CROSSTALK... more ... ROTEM AND SADOT: EFFECT OF THERMAL CHIRP ON INTERFEROMETRIC HOMODYNE AND HETERODYNE CROSSTALK ... 2) Adiabatic Chirp: As mentioned in the Introduction, adi-abatic chirp affects only mixing between bits with opposite values and, therefore, has a ...
Optical Fiber Communication Conference/National Fiber Optic Engineers Conference 2011, 2011
Abstract: Proposed adaptive decision-feedback CR method is ultimate in the sense that it is ML/... more Abstract: Proposed adaptive decision-feedback CR method is ultimate in the sense that it is ML/MMSE optimal (its performance cannot ever be exceeded) while its complexity vs. the num-ber of taps, L, is lowest O(L) order possible. OCIS codes: (060.1660) Coherent ...
Electroholography (EH) is a novel optical switching method, based on the photorefractive effect a... more Electroholography (EH) is a novel optical switching method, based on the photorefractive effect at the paraelectric phase, in which the diffraction from volume gratings is governed by an external electric field. Experimental evaluation of a 2x2 EH switch operating at 1.55µ, with data throughput better than 1.25 Gb/s is presented. Bit error rate (BER) measurements indicate, that coherent cross talk does not occur. Measurement of the switching speed was also performed, indicating a rise time of the grating shorter than 30 nsec. It is argued that the performance envelope of the EH switch opens the way for applications in which circuit switching is merged with packet switching.
The optical transmitter components may cause nonlinear distortions mixed with memory effect. Usin... more The optical transmitter components may cause nonlinear distortions mixed with memory effect. Using a system model identification scheme based on Volterra series, enable distortion root cause identification and design of efficient compensators to mitigate these effects.
Digital pre-compensation complementary to post equalization increases the digital signal processi... more Digital pre-compensation complementary to post equalization increases the digital signal processing (DSP) compensation envelope, especially in non-linear band-limited channels. The DSP at the transmitter relies on the availability of high-speed and high-resolution digital-to-analog devices to generate complex analog waveforms. However, one major challenge in high-speed digital-to-analog converter (DACs) technology is the limited resolution, which introduces dominant quantization distortions. Here, a new dynamic quantization technique is proposed, based on the fact that the quantization is a non-linear deterministic operation. Extensive lab experiments and numerical simulations demonstrate signal to quantization noise ratio improvement of up to 8 dB. In addition, an extremely low complexity modified Volterra digital pre-distortion (DPD) is developed, using orthogonal polynomial basis functions. Efficient grading method of the most dominant orthogonal dimensions is developed. The method combines both the dimensions variances and the impact of the information projection on each of the dimensions. The newly proposed modified Volterra DPD is shown to maximize the DPD performance while minimizing the number of required series dimensions. Extensive sets of lab experiments and simulations are performed, indicating potential saving of up to 89% in the amount of useful dimensions with a negligible error vector magnitude (EVM) penalty.
2016 18th International Conference on Transparent Optical Networks (ICTON), 2016
Large-scale data centers store a huge amount of the world's data in their cloud servers. To e... more Large-scale data centers store a huge amount of the world's data in their cloud servers. To ensure fast, reliable, low power, and low cost transmission, the communication channel between the server units is optical, at the highest available data rates of 100 - 400 Gbps. Consequently, all future solutions should rely on advanced communication techniques combined with high order modulation and digital signal processing (DSP).
Today, we are evident to the revolution of the automotive industry and its demand for high bandwi... more Today, we are evident to the revolution of the automotive industry and its demand for high bandwidth sensor fusion. Multiple high bandwidth sensors are connected, generating tremendous amount of data to be transferred in real-time in harsh environment, i.e., multi-gigabit intra-vehicle networks. Plastic optical fiber (POF) is an attractive medium for these multi-gigabit intra-vehicle networks due to its inherent EM compatibility, galvanic isolation, low weight, high tolerance to mechanical vibrations, low bending loss, and easy handling. However, commercial off-the-shelf PMMA based POFs are bandwidth-length product limited. Here, we suggest increasing the spectral efficiency using spatial-division multiplexing (SDM). In this article, we have experimentally demonstrated a low cost and eye-safe 3 × 3 multiple-input multiple-output (MIMO) SDM system over a 15 meters multicore (MC) POF using commercial optical components, e.g., RC-LEDs and Si-PIN photodiodes. A 3 × 1 spot-based cores coupler spatial multiplexer was developed to couple the optical components with the MC-POF. This system achieved raw data rates of 1.5 Gb/s and 2.4 Gb/s using offline-processed MIMO equalization. The proposed system enables a flexible and scalable optical MIMO system that can meet the requirements of the automotive industry.
Pre-distortion for an optical transmitter modeled with complex frequency selective nonlinearity a... more Pre-distortion for an optical transmitter modeled with complex frequency selective nonlinearity applicable to different system architecture, based on recurrent neural network is proposed. Several architectures are compared and above 20dB performance gain is presented.
A method for reducing the complexity of estimating multiple timing offset in time interleaved ana... more A method for reducing the complexity of estimating multiple timing offset in time interleaved analog to digital converter based on Fourier series decomposition is proposed. The timing offset of different slices of the time interleaved analog to digital converter can be understood as points on a curve, which represents the timing offset per slice. Thus, the estimation of the timing offset can also be achieved by fitting of the timing-offset-curve. The timing offset curve can be represented by a kernel regression coefficient which are orthonormal on a limited set, thus replacing the estimation of timing offset per slice with the estimation of the regression kernel coefficients. In this paper, the idea of estimating kernel coefficients by using Fourier series analysis is presented and analyzed. When the timing offset of different slices are highly correlated, it is shown that an improvement of 3 dB can be achieved with ∼75% reduction in complexity, 6 dB improvement with ∼60% reduction and 10 dB with ∼40% reduction in respect to similar linear methods.
We propose a method for stealthy, covert, fiber-optic communication. In this method, the power of... more We propose a method for stealthy, covert, fiber-optic communication. In this method, the power of the transmitted signal is spread and lowered below the noise level both in time as well as in frequency domains which makes the signal “invisible”. The method is also efficient in jamming avoidance.
2017 European Conference on Optical Communication (ECOC), 2017
Encryption and steganography of the physical layer are experimentally demonstrated. We show a coh... more Encryption and steganography of the physical layer are experimentally demonstrated. We show a coherent stealthy transmission of 16 Gbps under negative −15 dB OSNR with pre-FEC BER of 1e-3, co-transmitted with public channel.
... ROTEM AND SADOT: EFFECT OF THERMAL CHIRP ON INTERFEROMETRIC HOMODYNE AND HETERODYNE CROSSTALK... more ... ROTEM AND SADOT: EFFECT OF THERMAL CHIRP ON INTERFEROMETRIC HOMODYNE AND HETERODYNE CROSSTALK ... 2) Adiabatic Chirp: As mentioned in the Introduction, adi-abatic chirp affects only mixing between bits with opposite values and, therefore, has a ...
Optical Fiber Communication Conference/National Fiber Optic Engineers Conference 2011, 2011
Abstract: Proposed adaptive decision-feedback CR method is ultimate in the sense that it is ML/... more Abstract: Proposed adaptive decision-feedback CR method is ultimate in the sense that it is ML/MMSE optimal (its performance cannot ever be exceeded) while its complexity vs. the num-ber of taps, L, is lowest O(L) order possible. OCIS codes: (060.1660) Coherent ...
Electroholography (EH) is a novel optical switching method, based on the photorefractive effect a... more Electroholography (EH) is a novel optical switching method, based on the photorefractive effect at the paraelectric phase, in which the diffraction from volume gratings is governed by an external electric field. Experimental evaluation of a 2x2 EH switch operating at 1.55µ, with data throughput better than 1.25 Gb/s is presented. Bit error rate (BER) measurements indicate, that coherent cross talk does not occur. Measurement of the switching speed was also performed, indicating a rise time of the grating shorter than 30 nsec. It is argued that the performance envelope of the EH switch opens the way for applications in which circuit switching is merged with packet switching.
The optical transmitter components may cause nonlinear distortions mixed with memory effect. Usin... more The optical transmitter components may cause nonlinear distortions mixed with memory effect. Using a system model identification scheme based on Volterra series, enable distortion root cause identification and design of efficient compensators to mitigate these effects.
Digital pre-compensation complementary to post equalization increases the digital signal processi... more Digital pre-compensation complementary to post equalization increases the digital signal processing (DSP) compensation envelope, especially in non-linear band-limited channels. The DSP at the transmitter relies on the availability of high-speed and high-resolution digital-to-analog devices to generate complex analog waveforms. However, one major challenge in high-speed digital-to-analog converter (DACs) technology is the limited resolution, which introduces dominant quantization distortions. Here, a new dynamic quantization technique is proposed, based on the fact that the quantization is a non-linear deterministic operation. Extensive lab experiments and numerical simulations demonstrate signal to quantization noise ratio improvement of up to 8 dB. In addition, an extremely low complexity modified Volterra digital pre-distortion (DPD) is developed, using orthogonal polynomial basis functions. Efficient grading method of the most dominant orthogonal dimensions is developed. The method combines both the dimensions variances and the impact of the information projection on each of the dimensions. The newly proposed modified Volterra DPD is shown to maximize the DPD performance while minimizing the number of required series dimensions. Extensive sets of lab experiments and simulations are performed, indicating potential saving of up to 89% in the amount of useful dimensions with a negligible error vector magnitude (EVM) penalty.
2016 18th International Conference on Transparent Optical Networks (ICTON), 2016
Large-scale data centers store a huge amount of the world's data in their cloud servers. To e... more Large-scale data centers store a huge amount of the world's data in their cloud servers. To ensure fast, reliable, low power, and low cost transmission, the communication channel between the server units is optical, at the highest available data rates of 100 - 400 Gbps. Consequently, all future solutions should rely on advanced communication techniques combined with high order modulation and digital signal processing (DSP).
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Papers by Dan Sadot