Digital pre-compensation (DPC) is an indispensable block of state-of-the-art optical transceivers, and a key enabler for high-order modulation formats (HOMFs) transmission. A crucial component, which enables the transmission precompensated HOMFs, digital-to-analog-converter (DAC). However, as data symbol rates grow, implementation such devices becomes highly challenging in terms performance, power consumption, costs. In this paper, digital-resolution-enhancer (DRE) algorithm discussed,...

The concept of multi-homodyne coherent detection is used for stealth and secured optical communications, demonstrating a transmission rate 20 Gbps under negative (in dB) signal-to-noise ratio (OSNR), in deployed multi-core fiber (MCF) network. A 10 GBd QPSK signal assigned with bandwidth multi-hundreds GHz, optically encoded spectral phase mask, transmitted below ASE noise the MCF channel. To enable such scheme, semiconductor based gain-switched laser (GSL) frequency comb, as both carrier...

Optical communication systems often include nonlinear components, such as Mach-Zehnder modulators (MZMs). The components' nonlinearity may have a deleterious effect on the system performance, especially when memory is included. One of most common methods to mitigate resultant distortion effects digital predistortion (DPD) based Volterra polynomial model. Typically, DPD coefficients are extracted using least squares approach. However, naive implementation model usually introduces significant...

A novel all-optical stealth and secured transmission is proposed demonstrated. Spectral replicas of the covert signal are carried by multiple tones a gain switched optical frequency comb, optically coded with spectral phase mask, concealed below EDFA's noise. The signal's spectrum spread far beyond bandwidth coherent receiver, thus forcing real time processing. An unauthorized user, who does not possess knowledge on can only obtain noisy distorted signal, that cannot be improved...

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 transmitter relies on availability of high-speed and high-resolution digital-to-analog devices generate complex analog waveforms. However, one major challenge converter (DACs) technology is limited resolution, which introduces dominant quantization distortions. Here, a new dynamic technique proposed, based...

We demonstrate a novel low-cost photonic-layer secured communication system that incorporates intensity modulation direct detection (IM/DD) scheme with 4-level pulse amplitude (PAM-4). In the proposed system, signal is buried under an amplifier's spontaneous emission (ASE) noise and coded spectral phase mask. As result, stealthy encrypted in both frequency time domains. analyze reception performance of detection, analytically compare its SNR conventional PAM-4 demonstrating only eligible...

We show in an experiment a covert transmission of QPSK and 64-QAM over up to 100km SSMF, digitally encrypted with spectral phase mask, buried under ASE noise negative -15 dB/0.1nm OSNR. record post-FEC error free BER for stealthy channel, at 16 Gbps on single polarization.

Digital precompensation (DPC) is considered a promising technique for high-throughput optical communication systems. The digital signal processing (DSP) at the transmitter relies on availability of high-speed and high-resolution digital-to-analog devices to generate complex analog waveforms. However, one major challenge in current converters (DACs) technology limited resolution, which introduces dominant quantization distortions when extensive DSP implemented. In this paper, dynamic approach...

A novel algorithm is proposed to overcome bandwidth limitation using low-resolution DACs. We demonstrate electrical back-to-back 32Gbaud QAM-64 over 11GHz and optical QAM-4 5GHz 4 bits 2.6 DACs respectively.

DSP techniques that enhance the effective resolution of digital-to-analog converters (DACs) are presented. First, DACs limited by physical number bits (PNOB) addressed. An improved digital-resolution-enhancer (DRE) algorithm, which incorporates an optimized non-uniform quantization scheme is analytically analyzed and experimentally demonstrated. Improvement up to 8 dB shown, enables 16QAM 64QAM transmission using only 2 3 DACs, respectively. Furthermore, DRE concept elaborated include...

A new generation of combined ADC-DSP scheme is proposed. It based on a novel non-uniform quantization method, optimized for MLSE receivers. This inclusive optimization enables the use extremely low-resolution analog-to-digital-converters devices, which form major bottleneck in high speed optical communications receivers' architecture. Through Monte-simulation it demonstrated that proposed method leads to significant SNR gain over conventional designs, and may provide low cost power...

A stealthy and encrypted transmission is demonstrated in a dense-WDM network. The residual gap between two neighboring commercial channels utilized for the of secured channel, hidden below amplifier noise at negative -10 dB/0.1nm OSNR. channel generated by digital replication baseband signal together with spectral phase mask. This technique provides encryption steganography as it exclusively allows eligible user to obtain considerable processing-gain, recover extremely low OSNR signals. In...

Digital precompensation complementary to post equalization increases the DSP compensation envelope. Implementable parallel least square of nonlinear bandlimited channel, asymmetric imbalance predistortion MZM impairments, and quantization noise preshaping minimizing DAC resolution requirement are presented.

A novel dynamic quantization algorithm is proposed to support pre-compensation using low resolution DACs. Electrical back-to-back 50Gbaud PAM-4 transmission over 11Ghz bandlimited infrastructure demonstrated 3 bits DAC.

As data centers evolve to sustain the economic scale in network traffic, optical interconnections are adapted support vast amount of capacity requirements. Among emerging solutions is incorporation digital-signal-processing (DSP) functionalities at receiver compensate for fiber and optoelectronic components impairments. The bottleneck such architecture often implementing a high-resolution high-speed analog-to-digital-converter (ADC) device, which usually leads massive power consumption high...

In this work we propose a novel and efficient characterization scheme for narrow linewidth laser using nearly-coherent delayed self-homodyne (NC-DSH) technique. The modulated signal of an analog coherent optics (ACO) transceiver, configured in optical loop-back, the local oscillator (LO) are mixed after very short path difference (OPD), corresponding to interferometer operating its regime. phase noise is extracted from digital processing algorithm carrier estimation (CPE), while data...

Employing DACs with low resolution plays a significant role in reducing the transponder power consumption. We experimentally verified benefit of digital enhancer by transmitting WDM 400G-64QAM using 4 physical bits DAC over DCI distances.

We present a numerical study of probabilistic constellation shaping gains in low resolution digital to analogue converters based transceivers, which utilise enhancement. A signal noise ratio gain 0.75dB for optimized factors is achievable.

We present a novel 128 Gbps SP-16QAM FSOC experiment, conducted in retro-reflected setup over 10 km through the atmosphere. The optical is presented, and results are further discussed along with limiting factors.

An efficient grading method for dimensions-reduced digital pre-distorter based on orthogonal Volterra series band-limited nonlinear components is proposed. The a combination of dimension variance and signal-projection.

High-speed optical communication systems may suffer from a combination of impairments such as memory effect and nonlinear behavior the optoelectronic components. Nonlinear digital pre-distortion (DPD) is one well-known technique to alleviate these effects. As typical implementation Volterra-based DPD considered complex consumes high power, more efficient orthogonal-based Volterra series representation has been proposed. Previous works offered ways perform grading most dominant dimensions...

Advances in digital hardware had enabled a new generation of fiber optics communication receivers. Extensive digital-signal-processing (DSP) allows compensating for channel impairments and, turn, scaling up data rate. One the main challenges modern receivers is implementing high-rate, high-precision analog-to-digital-converter (ADC) that could meet system requirements. Since ADCs technology usually far from highest rates available, reducing required resolution imperative present and future...

A new generation of combined ADC-DSP scheme is proposed. It based on a novel non-uniform quantization method, optimized with MLSE receivers. This inclusive optimization enables effective channel compensation using extremely low resolution ADC-DSP.