A simple all-optical format transparent time and wavelength demultiplexing technique for WDM &amp;amp; orthogonal-TDM Nyquist channels

Shoaie, Mohammad Amin; Vedadi, Armand; Brès, Camille‐Sophie

doi:10.1109/ecoc.2015.7341745

Cited by 5 publications

(3 citation statements)

References 10 publications

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“…Figure 2 highlights the rectangular shape of the optical combs of all cases. Despite a limiting optical spectrum analyser resolution (0.02 nm), the side-mode suppression ratio can be measured at least greater than 28.5 dB, giving potential for Nyquist channel multiplexing with minimum interference on adjacent channels [11]. The Sinc-shaped pulse obtained show the clear main peak followed by the subsequent symmetric side lobes indicating the alignment of the relative phase.…”

Section: Resultsmentioning

confidence: 93%

Optical Sinc-shaped Nyquist pulse source based on a single Mach-Zehnder modulator

Fabbri

Brès

2017

2017 19th International Conference on Transparent Optical Networks (ICTON)

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We present a precise and flexible Sinc-shaped Nyquist pulse source based on a single Mach-Zehnder modulator. The use of multi-harmonic RF signals provides direct control on the Nyquist pulse train generation. The variable comb source is demonstrated by selecting the number of RF components used to drive the optical modulator, leading from 3 to 9 comb lines. Furthermore, different operating points are reported to show the multi-harmonic comb generator potential to provide near-perfect Nyquist pulse source with pure rectangular optical spectrum or with minimized insertion loss. Keywords: Sinc-shaped Nyquist pulse, optical frequency comb, electro-optic modulation. INTRODUCTIONGeneration of Sinc-shaped optical Nyquist pulses is essential for a wide range of applications in optical telecommunications, RF photonics, and optical signal processing. Indeed, due to its rectangular spectrum and zero inter-symbol interference (ISI) in time domain, the newly developed optical orthogonal time division multiplexing (O-OTDM) and Nyquist WDM technique [1] can achieve comparable spectral efficiency as optical orthogonal frequency division multiplexing (O-OFDM), while the receiver complexity is reduced and it is less sensitive to the nonlinearities of the link. Besides, since the Nyquist pulse train corresponds to a number of optical frequency combs in spectrum with equal amplitude and linear spectral phase, it can be utilized to implement optical or microwave filters with rectangular spectrum [2]. In addition, all-optical sampling using Nyquist pulses has recently been demonstrated based on external modulators with tunable sampling speed [3], thereby avoiding the need for nonlinear mixing with short optical pulse as the gating function.Therefore, considerable efforts have been placed to generate Sinc-shaped Nyquist pulses with a variety of methods [4][5][6][7][8]. By cascading two Mach-Zehnder modulators (MZM) with synchronized RF frequencies (f, 3f) to each of the modulator, near-ideal Sinc-shaped Nyquist pulses were obtained with the corresponding 9-line comb spectrum [4]. Sinc-shaped Nyquist pulses were also demonstrated using a single dual-parallel Mach-Zehnder modulator (DP-MZM) with 5 spectral comb lines [5]. In [6], by putting a segment of dispersion compensating fiber (DCF) in between a phase modulator (PM) and a MZM, serving as a modified lens, Nyquist pulses were generated with a 11-line comb spectrum after a selective bandpass filter. In order to expand the spectrum, and therefore narrowing the Nyquist pulse width, four-wave mixing technique were utilized with the help of a waveshaper to tailor the spectrum [7]. Indeed, liquid crystal spatial light modulator can be used to implement line-by-line shaping of mode locked laser spectrum or super-continuum comb source into Nyquist pulses, with the full control of the amplitudes and the relative phases [8]. In order to obtain flatter and wider optical combs, more than one RF clock were used in [9] to smooth the central region of the output spectrum from a single asym...

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Section: Resultsmentioning

confidence: 93%

Optical Sinc-shaped Nyquist pulse source based on a single Mach-Zehnder modulator

Fabbri

Brès

2017

2017 19th International Conference on Transparent Optical Networks (ICTON)

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“…The multiplexed signal is divided into N branches for simultaneous processing. In each branch, the corresponding channel will be demultiplexed by multiplying the multiplexed signal with a sinc-pulse sequence 20 . Due to orthogonality, the channel, which has to be demultiplexed, is defined by the time shift of the sequence.…”

Section: Principlesmentioning

confidence: 99%

The agnostic sampling transceiver

Misra,

Meier,

Singh

et al. 2020

Preprint

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Increasing capacity demands in the access networks require inventive concepts for the transmission and distribution of digital as well as analog signals over the same network. Here a new transceiver system, which is completely agnostic for the signals to be transmitted is presented. Nyquist sampling and time multiplexing of N phase and intensity modulated digital and analog channels with one single modulator, as well as the transmission and demultiplexing with another modulator have been demonstrated. The aggregate symbol rate corresponds to the modulator bandwidth and can be further increased by a modification of the setup. No high-speed electronic signal processing or high bandwidth photonics is required. Apart from its simplicity and the possibility to process high bandwidth signals with low bandwidth electronics and photonics, the method has the potential to be easily integrated into any platform and thus, might be a solution for the increasing data rates in future access networks.

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“…The method is based on a convolution between a frequency comb and the signal spectrum in two coupled modulators. A similar technique can be used for the demultiplexing of Nyquist channels 7 . The basic principle of all-optical sampling based on frequency-time coherence is depicted in Fig.…”

Section: Theorymentioning

confidence: 99%

Frequency-time coherence for all-optical sampling without optical pulse source

Preußler

Mehrpoor

Schneider

2016

Sci Rep

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Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave. Since no optical source is required, a simple integration in appropriate platforms, such as Silicon Photonics might be possible. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift.

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A simple all-optical format transparent time and wavelength demultiplexing technique for WDM & orthogonal-TDM Nyquist channels

Cited by 5 publications

References 10 publications

Optical Sinc-shaped Nyquist pulse source based on a single Mach-Zehnder modulator

Optical Sinc-shaped Nyquist pulse source based on a single Mach-Zehnder modulator

The agnostic sampling transceiver

Frequency-time coherence for all-optical sampling without optical pulse source

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