Simultaneous Demultiplexing Research Articles

Characterization of a multifunctional active demultiplexer for optical frequency combs

We report on a multifunctional active demultiplexer for optical frequency combs. The proposed technique, based on injection locking, combines the functionality of a tunable demultiplexer, gain equalizer and an optical amplifier, all in one device. Validation of the concept is experimentally demonstrated through simultaneous demultiplexing and amplification of combs with various free spectral ranges (2.5 to 15 GHz), achieving an adjacent channel suppression ratio > 35 dB and an output power of 7.5 dBm. The functionality of the demultiplexer is extended to that of a gain equalizer, by filtering comb tones with powers 10 dB below the spectral peak, whilst maintaining a suppression ratio > 30 dB and a constant output power. This feature increases the number of comb lines suited for data modulation (i.e. usable lines), by a factor of ~1.7. Finally, we test the stability of such a demultiplexer, by measuring the frequency drift, beat tone power variations and phase correlation between demultiplexed tones.

Simultaneous demultiplexing of 2 × PDM-PAM4 signals using simplified receiver.

Simultaneous transmission of two polarization-division-multiplexing four-level pulse-amplitude-modulation (2 × PDM-PAM4) signals is proposed, and a simplified receiver is used for demultiplexing two data streams. Experimental results at 160-Gbit/s show that the power penalty of each data stream is ~0.4-dB (back-to-back) and ~1-dB (25-km transmission) compared with the single PDM system. Furthermore, the stabilization of the proposed scheme is investigated. The BER fluctuation is <0.5-dB at a polarization scrambling rate up to 1417.5-deg/s.

Preamplified Demodulation of 56-Gb/s WDM-DPSK Signals by an AWG-Based InP PIC

A compact preamplified receiver for wavelength division multiplexed-diffferential phase shift keying (WDM-DPSK) signals based on Gaussian filtering is proposed and simulated, and a first implementation, including an semiconductor optical amplifiers (SOA) and an ad-hoc arrayed waveguide grating (AWG), is demonstrated by monolithical integration in an InP platform. The demodulation of 56-Gb/s channels on the eight 100-GHz-spaced AWG outputs is experimentally reported, and simulation results show the feasibility of multiwavelength operation obtaining simultaneous demultiplexing and demodulation of all the channels. The resilience to chromatic dispersion for the Gaussian filter demodulation is also shown by simulations.

Simultaneous demultiplexing and steering of multiple orbital angular momentum modes

We present a simple scheme to perform simultaneous demultiplexing and steering of multiple orbital angular momentum (OAM) modes using a single complex phase mask. By designing the phase mask, the propagation directions of demultiplexed beams can be arbitrarily steered. System experiments using orthogonal frequency-division multiplexing 32-ary quadrature amplitude modulation (OFDM-32QAM) signals over two OAM modes are carried out by using a two-mode complex phase mask. Moreover, demultiplexing of sixteen OAM modes and arbitrary demultiplexed beam steering are also demonstrated in the experiment.

A Plasmonic Photonic Diode for Unidirectional Focusing, Imaging, and Wavelength Division De-Multiplexing

A thin-film photonic lens is fabricated using chirped plasmonic grating structures, which enables off-axis focusing and simultaneous de-multiplexing of the incident light beams, as well as the intrinsic function of an optical lens for imaging. This planar two-dimensional photonic device may be used either as a positive (converging) or a negative (diverging) lens through controlling how the light beam is incident and how the device is oriented, which defines multifold ‘diode’ effects and is thus termed “forward” or “backward” biasing of such a ‘diode’ lens. This plasmonic photonic diode (PPD) features by unidirectional functions instead of non-reciprocal transmission. These unique functions are demonstrated by focusing different colors into different angles and different focal lengths with large dispersions, which enables direct wavelength division de-multiplexing with high resolution and high efficiency. Strong plasmonic scattering by the gold nanolines that constitute the chirped grating structures leads to efficient operation and polarization-dependent performance of the PPD device.

Simultaneous demultiplexing into two 10 Gbit/s using a bidirectionally operated highly nonlinear fiber

A simultaneous two-channel optical time division multiplexing (OTDM) demultiplexing is proposed and experimentally demonstrated by using a bidirectionally operated highly nonlinear fiber followed by a narrow-band offset filter. The performance of the proposed demultiplexer is evaluated in an 80 Gbit/s OTDM transmission system. A maximum power penalty of 2.6 dB is obtained for the worst demultiplexed channel. The proposal might be interesting since it offers a powerful tool for developing ultrafast photonic networks.

Effective optical clock recovery and simultaneous fourfold demultiplexing of OTDM signal using an optoelectonic oscillator

We propose and demonstrate a novel scheme for clock recovery and simultaneous fourfold optical time-division demultiplexing using a dual-parallel Mach-Zehnder modulator based optoelectronic oscillator. 25-GHz prescaled optical clock with a 23% duty cycle and a 22-dB extinction ratio is successfully extracted from both 100-Gb/s on-off keying (OOK) and differential phase-shift keying (DPSK) optical time-division-multiplexing (OTDM) signal. The timing jitters (100 Hz to 10 MHz) are measured to be 195.9 fs and 125.6 fs for the optical clock extracted from the 100-Gb/s OOK and DPSK signal, respectively. Error-free optical time-division demultiplexing is also achieved simultaneously with clock recovery. By adjusting the phase shifter in the OEO loop, all four channels can be selectively demultiplexed. The power penalties at a bit error rate (BER) of 10⁻⁹ for the four demultiplexed channels are measured to be between 0.8 dB and 1.2 dB for the OOK signal and between 0.9 dB and 1.5 dB for the DPSK signal.

Simultaneous Demultiplexing and Demodulation of 10 Gbit/s RZ-DPSK Signal using Arrayed Waveguide Gratings

We propose and demonstrate simultaneous demultiplexing and demodulation of wave length division multiplexed (WDM) return-to-zero differential phase-shift keying (RZ-DPSK) signal by a standard Arrayed Waveguide Gratings (AWG) at 10 Gbit/s data rate using ITU grid of 100 GHz channel spacing. Simulation results show error free transmission in a distance of 25 km with negligible power penalty and improved receiver sensitivity. The propose scheme is cost effective in term of component counts, hence reduces the deployment cost significantly.

Ultra-low timing-jitter 40GHz clock recovery using EAM-MZM double-loop and its application in a 640Gbit/s OTDM system

An ultra-low timing-jitter clock recovery scheme based on EAM-MZM double-loop with the ability of simultaneous time-division demultiplexing is proposed and demonstrated in a 640 Gbit/s OTDM transmission system. Compared with traditional clock recovery scheme based on OEO loop, significant timing-jitter improvement of the 40 GHz recovered clock is realized: from 58 fs to 30 fs in back-to-back configuration and from 59 fs to 35 fs after 400 km transmission in the 100 Hz to 10 MHz range, without increasing the overall system complexity and cost. Enabled by the proposed clock recovery and demultiplexing scheme, error-free performance of the OTDM system is achieved after 400 km transmission with an average power penalty of 4dB.

Features of the diffraction of supershort pulsed radiation in a system of superimposed transmitting volume phase holographic gratings

This paper discusses how the shape and spectrum of supershort radiation pulses are transformed as a result of diffraction at superimposed transmitting volume phase holographic gratings. It shows that de-interleaving of the light signal with simultaneous demultiplexing in the diffracted beam can be carried out in such a system.

Novel RZ-CW conversion scheme for ultra multi-level, high-speed coherent OTDM transmission

A novel coherent multi-level OTDM transmission scheme is presented by using an RZ-CW conversion technique in a coherent receiver, in which the transmitted coherent RZ pulses are OTDM demultiplexed and converted into a CW signals for demodulation with a CW-LO. This scheme enables us to achieve a high SNR demodulation and demultiplexing performance even for ultrahigh-speed OTDM signals with ultra multi-level modulation, which would be difficult to realize with a conventional scheme of simultaneous demodulation and demultiplexing using a pulsed-LO. The advantage of this scheme is successfully demonstrated with 10 Gsymbol/s, 4- and 8-OTDM, 32-RZ/QAM demodulation experiments.

Simultaneous Clock Enhancing and Demultiplexing for 160-Gb/s OTDM Signal Using Two Bidirectionally Operated Electroabsorption Modulators

We demonstrate a technique for performing optical time-division simultaneous clock enhancing and demultiplexing using two bidirectionally operated electroabsorption modulators (EAMs). The performance of the proposed setup is verified experimentally in a 160-Gb/s 100-km transmission system. The 10-GHz clock component is enhanced before launching into the clock recovery module. The recovered 10-GHz clock signal is featured with low timing jitter ( <;300 fs) and error-free transmission is achieved with the power penalty of ~ 0.9 dB. The proposed setup has merits of simultaneously enhancing base clock component and demultiplexing.

Reconfigurable two-channel demultiplexing using a single baseband control pulse train in a dispersion asymmetric NOLM

We demonstrate a unique solution to use a one-pulse control to achieve simultaneous two-channel all-optical demultiplexing that usually requires a two-pulse control or a two-step operation based on the conventional approaches. By applying a dispersion asymmetric nonlinear optical loop mirror (DA-NOLM) to introduce cross phase modulation (XPM) in both the clockwise (CW) and the counter clockwise (CCW) propagating branches, we have demonstrated reconfigurable, error-free 40-to-10 Gb/s two-channel demultiplexing (DEMUX) for OTDM OOK signals. Switchable operation between two-channel and single-channel DEMUX is also realized based on the proposed all-optical DEMUX configuration.

Simultaneous demodulation and demultiplexing of multi-rate WDM DPSK signals using a programmable wavelength-selective switch

We show demodulation and demultiplexing of multi-channel WDM differential phase-shift-keying (DPSK) signals operating simultaneously at 10 Gb/s and 40 Gb/s using a 1x4 wavelength selective switch. We achieve error-free performance for four channels equally spaced by 100 GHz propagated over an 85 km dispersion-compensated link. We study the advantages and limitations of this new DPSK demodulator compared with the conventional delay-line interferometer.

Demultiplexer/Photodetector Integrated System Based on a-SiC:H Multilayered Structures

AbstractIn this paper we present results on the use of multilayered a-SiC:H heterostructures as an integrated device for simultaneous wavelength-division demultiplexing and measurement of optical signals. These devices are useful in optical communications applications that use the wavelength division multiplexing technique to encode multiple signals into the same transmission medium.The device is composed of two stacked p-i-n photodiodes, both optimized for the selective collection of photo generated carriers. Band gap engineering was used to adjust the photogeneration and recombination rates profiles of the intrinsic absorber regions of each photodiode to short and long wavelength absorption and carrier collection in the visible spectrum. The generated photocurrent signal using different input optical channels was analyzed at reverse and forward bias and under steady state illumination. A demux algorithm based on the voltage controlled sensitivity of the device was proposed and tested. An electrical model of the WDM device is presented and supported by the solution of the respective circuit equations. Other possible applications of the device in optical communication systems are also proposed.

Multicast Parametric Synchronous Sampling of 320-Gb/s Return-to-Zero Signal

Technology for simultaneous demultiplexing of subrate tributaries is described and applied to 320-Gb/s return-to-zero input. The parametric architecture is scalable with respect to processed input rate and relies on cascaded all-optical multicasting and subrate sampling. Processing of 320-Gb/s input was achieved by creating eight channel copies, followed by a 20-THz-wide parametric gate. Multicasting was based on a self-seeded two-pump broadband fiber-optic parametric amplifier. The architecture was used to demonstrate error-free parallel demultiplexing of eight 320-Gb/s tributary channels at 40 Gb/s.

A Simple Loop for Simultaneous OTDM Demultiplexing and Clock Recovery

A simple and stable loop consisting of a pair of concatenated electroabsorption modulators (EAMs) and 10 GHz clock recovery module is presented and demonstrated experimentally for simultaneous demultiplexing and clock recovery for OTDM networks. The 10Gb/s demultiplexed signal and 10 GHz recovered clock are successfully implemented from 80 Gbit/s and 160 Gbit/s OTDM signals utilizing the loop. The loop based on EAM-PLL can provide excellent tolerance range (> 5 dB) of the OSCR of the source laser, and the recovered clock signal exhibits low rms jitter over a dynamic input optical power range of 15 dB.

All-optical serial-to-parallel converter for simultaneous multiple-channel OTDM demultiplexing

Proposed is a novel structure of a cascadable photonic serial-to-parallel converter (SPC) based on the cross-phase modulation effect in a semiconductor optical amplifier for simultaneous multiple-channel optical time division multiplexed demultiplexing. The proposed SPC features cascadability, compact structure, high-speed operation, and simultaneous two-channel operation. Error-free 20 Gbit/s simultaneous two-channel demultiplexing is experimentally demonstrated.

Highly Stable 160-Gb/s OTDM Technologies Based on Integrated MUX/DEMUX and Drift-Free PLL-Type Clock Recovery

This paper reports 160-Gb/s optical time-division-multiplexed (OTDM) technologies including an all-optical integrated multiplexer (MUX) providing all-channel independent modulation, an all-optical integrated demultiplexer (DEMUX) that offers all-channel simultaneous demultiplexing, and a drift-free phase-locked-loop (PLL)-type clock recovery circuit for ultrahigh-speed OTDM signals. We present the configuration of each technology and the results of experiments on those technologies. Highly stable operation is successfully demonstrated by using a MUX based on periodically-poled lithium niobate (PPLN) hybrid integrated planer lightwave circuit (PLC), a DEMUX based on semiconductor optical amplifier hybrid integrated PLC, and clock recovery circuit based on a PLL with an optical phase modulator and a PPLN waveguide

Simultaneous multiplexing and demultiplexing of wavelength-interleaved channels in DWDM millimeter-wave fiber-radio networks

A simultaneous multiplexing and demultiplexing (MUX/DEMUX) scheme for wavelength-interleaved millimeter-wave 37.5-GHz-band fiber-radio channels spaced at 25 GHz has been proposed. The proposed MUX/DEMUX technique potentially realizes simple, compact, and low-cost central office and remote nodes by avoiding the use of wavelength-selective pre- and postprocessing hardware. The novel scheme incorporates an arrayed-waveguide grating with multiple loop-backs between the input and the output ports, in addition to multiple optical circulators and optical isolators. The multiplexing functionality of the proposed technology enables a carrier subtraction technique and consequently reduces the carrier-to-sideband ratios of the multiplexed channels. Multiplexing of the uplink channels generated via several methods is demonstrated experimentally. These techniques include generation of the channels by using the optical carriers that correspond to wavelengths spaced at the free spectral range (FSR) or multiples of the FSR from the downlink (DL) optical carriers and reuse of the DL optical carriers that are recovered by applying a wavelength reuse technique (lambdaUL =lambdaDLplusmnntimesFSR, where n=0,1,2,3,...). The demultiplexing functionality of the proposed scheme that separates the 37.5-GHz-band wavelength-interleaved DL channels spaced at 25 GHz is also demonstrated. In addition, the effect of optical crosstalk on the transmission performance of the demultiplexed channels is also characterized experimentally