Eye Diagram Measurements Research Articles

Thermally tunable GeSi electro-absorption modulator with a wide effective operating wavelength range

We demonstrate a GeSi electro-absorption modulator with on-chip thermal tuning for the first time, to the best of our knowledge. Theoretical simulation proves that the device temperature can be tuned and the effective operating wavelength range can be broadened. When the heater power is 4.63 mW, the temperature of the waveguide increases by about 27 K and the theoretical operating wavelength range is broadened by 23.7 nm. The experimental results show that the optical transmission line shifted to the longer wavelength by 4.8 nm by every 1 mW heater power. The effective static operating wavelength range of the device is increased from 34.4 nm to 60.1 nm, which means it is broadened by 25.7 nm. The band edge shift coefficient of 0.76 nm/K is obtained by temperature simulation and linear fitting of the measured data. The device has a 3 dB EO bandwidth of 89 GHz at 3 V reverse bias, and the eye diagram measurement shows a data rate of 80 Gbit/s for non-return-to-zero on–off keying modulation and 100 Gbit/s for 4 pulse amplitude modulation in the 1526.8 nm to 1613.2 nm wavelength range as the heater power increases from 0 mW to 10.1 mW.

Design of a Novel Ultra-Wideband Common-Mode Filter Using a Magnified Coupled Defected Ground Structure

An ultra-wideband common-mode (CM) filter for a gigahertz (GHz) data rate signal is proposed in this paper. The proposed filter was designed only on the printed circuit board (PCB) ground plane; no additional components wererequired. We took advantage of producing second-order transmission zero by an asymmetrical magnified coupled DGS to extend the suppression bandwidth. Full-wave simulations and equivalent circuit models of the DGS resonator were established to predict the suppression performance. The measured differential-mode insertion loss (Sdd21) from direct current (DC) to 12.35 GHz was obtained within the −3 dB definitionin the frequency domain. The CM noise was suppressed by more than10 dB in the frequency range from 2.9 GHz to 16.2 GHz. The fractional bandwidth (FBW) reached 139.3%. The proposed filter blocked 62.3% of the CM noise magnitude in the time domain measurement. In addition, the eye diagram measurement proved that good transmission quality was maintained. The proposed filter can be widely implemented to reduce electromagnetic interference (EMI) in radio frequency (RF) andWi-Fi (wireless fidelitystandard) 5 and 6E wireless communication applications.

80Gb/s NRZ Ge waveguide electro-absorption modulator.

We demonstrate a Ge electro-absorption modulator (EAM) in L band with a 3 dB electro-optical bandwidth beyond 67 GHz at -3 V bias voltage. The Eye diagram measurement shows a data rate of over 80 Gbps for non-return-to-zero on-off keying (NRZ-OOK) modulation at a voltage swing of 2.3 Vpp and the wavelength of 1605 nm. Through the comparison of multi-device results, it is proved that the introduction of the annealing process after CMP can increase the mean static extinction ratio of the EAM from 7.27 dB to 11.83 dB, which confirms the manufacturability of the device. The dynamic power consumption of the device is 6.348 fJ/bit. The performance of our device is comprehensive. The Ge EAM device also has excellent performance as a photodetector (PD) in the C and L communication bands. The responsivity of the device is 1.04 A/W at the wavelength of 1610 nm, resulting in ∼0.87 mW of static power consumption at -3 V bias voltage under 0.28 mW of optical input and the 3 dB opto-electric bandwidth of the devices are beyond 43 GHz at -3 V bias.

High-speed and high-power germanium photodetector based on a trapezoidal absorber.

A compact high-power germanium photodetector (Ge PD) is experimentally demonstrated by re-engineering light distribution in the absorber. Compared with a conventional Ge PD, the proposed structure shows a DC saturation photocurrent improved by 28.9% and 3 dB bandwidth as high as 49.5 GHz at 0.1 mA. Under the same photocurrent of 10.5 mA, the proposed Ge PD shows a 3 dB bandwidth of 11.1 GHz, which is almost double the conventional Ge PD (5.6 GHz). The 25 Gb/s eye-diagram measurement verifies the improved power handling capability. The compact size and manufacturing simplicity of this structure will enable new applications for integrated silicon photonics.

Asymmetric Optical Wavelength Switch Based on LCoS-SLM for Edge Node of Optical Access Network

A novel design of optical wavelength switch, based on an asymmetric switching architecture for edge node implementation, is presented in this paper. Compared to previous research for optical core transport network applications, the proposed work has a unique aspect to build dynamic multicasting and spectral equalization, vital functionalities for optical wavelength switch in the edge of optical access networks. An optical wavelength switch was experimentally implemented and evaluated in a 4 × 16 switching architecture to demonstrate the concept. This dynamic multicasting and spectral equalization were achieved by utilizing liquid crystal on a silicon spatial light modulator (LCoS-SLM) device. An optimal design of computer-generated holograms (CGHs) through an improved GS algorithm was used to perform the beam steering and wavelength switching. A variety of wavelength switching scenarios has been experimentally evaluated. The measurement results showed an average insertion loss of around -12.5 dB, and the calculated crosstalks were all less than -28 dB. Its applications in digital data transmissions were evaluated to achieve a transmission speed larger than 2.5 Gbps. The eye diagram measurement results showed that most wavelength switching scenarios have nearly bit-error-free transmission. The scenario includes the multicasting with spectral equalization within the proposed asymmetrical switching architecture.

Performance Analysis of ZCC-Optical-CDMA over SMF for Fiber-To-The-Home Access Network

To provide a sustainable fiber-to-the-home (FTTH), several multiplexing techniques have been developed for this purpose. The correlation features are the main obstacle behind the network performance limitation, which imposes to a high level of multiple access interference. However, the development of multiplexing techniques helps to overcome these limitations, such as optical-code division multiple access (Optical-CDMA). Optical-CDMA is considered as one of the most powerful solutions for FTTH. This paper aims to enhance FTTH network performance by applying Zero cross-correlation code (ZCC) with Optical-CDMA with maximum link single-mode fiber. In the simulation, the system performance is demonstrated in terms of bit error rate, Q-Factor and eye diagram measurements.

Ultra-Broadband, High Speed, and High-Quantum-Efficiency Photodetectors Based on Black Phosphorus.

Black phosphorus (BP), a narrow band gap semiconductor without out-of-plane dangling bonds, has shown promise for broadband and integrable photodetector applications. Simultaneously exhibiting high speed and high-efficiency operation, however, remains a critical challenge for current BP-based photodetectors. Here, we demonstrate a photodetector based on the BP-based van der Waals heterostructures. The developed photodetector enables broadband responses in the visible to mid-infrared range with external quantum efficiency ranging from 20 to 52% at room temperature. These results together with noise measurements indicate that the photodetector can detect light in the picowatt range. Furthermore, the demonstrated BP detector has ultrafast rise (1.8 ns) and fall (1.68 ns) times, and its photoresponse exhibits reproducible switching behavior even under consecutive and rapid light intensity modulations (2100 cycles, 200 MHz), as indicated by the eye-diagram measurement. By leveraging these features, we show our BP heterostructures can be configured as a point-like detector in a scanning confocal microscopy, useful for mid-infrared imaging applications.

Eye Diagram Measurement-Based Joint Modulation Format, OSNR, ROF, and Skew Monitoring of Coherent Channel Using Deep Learning

In this work, deep learning is used to monitor coherent channel performance with eye diagram measurement. Experiments show that the proposed technique can determine the modulation format, optical signal to noise ratio (OSNR), roll-off factor (ROF), and timing skew of a quadrature amplitude modulation (QAM) transmitter with high accuracy. Trained vanilla convolutional neural network (CNN) and MobileNet can be utilized to jointly monitor above four parameters with >98% prediction accuracy for 32 GBd coherent channels with quadrature phase shift keying (QPSK), 8-QAM or 16-QAM formats, under OSNR from 15 to 40 dB, IQ skew from −15 to 15 ps, ROF from 0.05 to 1. Our proposed deep learning approach outperforms many traditional machine learning methods, such as decision tree, k -nearest neighbor algorithm (KNN), and histogram of oriented gradient (HOG) based support vector machine (SVM). Unlike other optical performance monitoring approaches, the use of eye diagram measurement combined with deep learning could enable joint monitoring of multiple system performance parameters with reduced hardware implementation complexity. Comparing with vanilla CNN, MobileNet has relatively simplified iteration algorithm, thus reduces the requirement on the computational power, while still maintaining high accuracy for classification issues.

Achieving beyond-100-GHz large-signal modulation bandwidth in hybrid silicon photonics Mach Zehnder modulators using thin film lithium niobate

Mach-Zehnder electro-optic modulators (EOM) based on thin-film lithium niobate bonded to a silicon photonic waveguide circuit have been shown to achieve very high modulation bandwidths. Open eye-diagram measurements made in the time domain of beyond-small-signal modulation are used to support the modulation-sideband measurements in showing that such EOM’s can support high-frequency modulations well beyond 100 GHz.

Transimpedance amplifiers with 133 GHz bandwidth on 130 nm indium phosphide double heterojunction bipolar transistors

In this work, the authors present two transimpedance amplifier (TIA) circuits designed for fibre optical interconnect systems. They compare a common base (CB) topology with a common emitter (CE) shunt shunt feedback topology in terms of frequency response, power consumption, noise, and input impedance. The two TIAs are designed on a 130 nm indium phosphide double heterojunction bipolar transistor technology from Teledyne Scientific Company (TSC) with an 1 f(t)/f(max). of 520 GHz/1.15 TED and are measured in the frequency and time domains. They exhibit a transimpedance gain of 42 dBS2 with a 133 GHz bandwidth, the highest bandwidth reported in the literature and power consumption of 32.3 nikV tqr the C13 and 25.5 mW for the CE. Eye diagram measurements were conducted up to 64 Ghps and input referred noise density was measured at 30.2 pAh/root Hz for the CB and 13.9 pA.root Hz for the CE.

All-Optical Wavelength Multicasting in Quadruple Resonance-Split Coupled Silicon Microring Cavity

We demonstrate an all-optical four-channel wavelength multicasting in a coupled silicon microring resonator system. The scheme is based on two-photon-absorption-induced free carrier dispersion in silicon. The coupled cavity facilitates resonance splitting that is utilized as individual channels for multicasting. Using the split resonances, we achieve an aggregate multicasted data rate of 48 Gbps (4 × 12 Gbps). Moreover, we also present a detailed analysis and performance of the multicasting architecture using bit error rate and eye diagram measurements.

Codesign of Electrostatic Discharge Protection Device and Common Mode Suppression Circuit on Printed Circuit Board

A codesign of an electrostatic discharge (ESD) protection device and a common-mode suppression circuit on printed circuit board (PCB) for high-speed input/output interfaces is introduced in this paper. The characteristic and the circuit model of the ESD protection device are investigated and applied into the design of the common-mode suppression circuit. The proposed one-stage design of two-layered PCB structure performs –10-dB common-mode noise suppression from 2.22 to 2.76 GHz; the proposed two-stage design with additional common-mode suppression unit performs wideband suppression from 2.25 GHz to over 8 GHz, covering IEEE 802.11ac WiFi band with –20-dB suppression level. The mode conversion for both designs is lower than –30 dB. The signal integrity and the ESD protection function of proposed design are investigated by eye diagram measurement and system-level ESD simulation. The proposed PCB design provides a low-cost solution for the integration on the high-speed input/output interface of next generation.

A 65-nm 10-Gb/s 10-mm On-Chip Serial Link Featuring a Digital-Intensive Time-Based Decision Feedback Equalizer

A digital-intensive on-chip serial link achieving a 10 Gb/s data rate over a 10-mm interconnect was demonstrated in a 65-nm GP process. A three-tap half-rate feed-forward equalizer was implemented for signal pre-emphasis in the transmitted block. On the receiver (RX) side, a two-tap half-rate time-based decision feedback equalizer was employed to cancel out inter-symbol interference noise. A 215 – 1 pseudorandom binary sequence generator and an in situ bit error rate (BER) monitor were designed for bit stream generation and convenient eye-diagram measurements. The measured energy efficiency of the transmitter and RX was 31.9 and 45.3 fJ/b/mm, respectively, for a data rate of 10 Gb/s. A BER less than 10−12 was verified for an eye width of 0.43 unit interval.

High-speed Si/GeSi hetero-structure Electro Absorption Modulator.

The ever-increasing demand for integrated, low power interconnect systems is pushing the bandwidth density of CMOS photonic devices. Taking advantage of the strong Franz-Keldysh effect in the C and L communication bands, electro-absorption modulators in Ge and GeSi are setting a new standard in terms of device footprint and power consumption for next generation photonics interconnect arrays. In this paper, we present a compact, low power electro-absorption modulator (EAM) Si/GeSi hetero-structure based on an 800 nm SOI overlayer with a modulation bandwidth of 56 GHz. The device design and fabrication tolerant process are presented, followed by the measurement analysis. Eye diagram measurements show a dynamic ER of 5.2 dB at a data rate of 56 Gb/s at 1566 nm, and calculated modulator power is 44 fJ/bit.

40-Gb/s TDM-PON Downstream Link With Low-Cost EML Transmitter and APD-Based Electrical Duobinary Receiver

We report a cost-effective 40-Gb/s time-division multiplexing passive optical network downstream link using three-level electrical duobinary modulation. The transmitter consists of a compact electroabsorption-modulated laser module. The receiver contains an avalanche photodiode packaged with a transimpedance amplifier, with digitally adjustable gain and bandwidth, followed by a duobinary decoder. Real-time eye diagram and bit-error rate (BER) measurements were performed. At a preforward error correction BER of $10^{-3}$ , a power budget of 23.6 dB in back-to-back conditions is demonstrated. For a dispersion range of −215 to 128 ps/nm, the power penalty does not exceed 3 dB.

An ultra-low crosstalk and broadband two-mode (de)multiplexer based on adiabatic couplers.

A novel adiabatic couplers (ACs) based broadband and fabrication-tolerant two-mode multiplexer (MUX) is designed using silicon-on-insulator (SOI) platform. Being different from the previously reported ACs-based scheme, the converted and multiplexed signals are on conventional modes, rather than supermodes. The experimental results are in good agreement with the simulations. Over a wavelength range of 75 nm measured, the crosstalk is lower than −20 dB, and the insertion loss is ~1 dB. The eye diagram and bit error rate measurements validate the good performance of the proposed mode MUX. The investigation on fabrication tolerance indicates reasonable performance degradation for a large gap deviation from −30 to 30 nm and etching depth deviation from −50 to 50 nm.

55-nm SiGe BiCMOS Distributed Amplifier Topologies for Time-Interleaved 120-Gb/s Fiber-Optic Receivers and Transmitters

Two distributed circuits based on MOS-HBT cascodes are reported in a 55-nm SiGe BiCMOS technology and are aimed at a single-chip time-interleaved transceiver for future 1-Tb/s optical links. The first, a DC-135-GHz single-ended distributed amplifier (DA) was optimized for low noise, linear receivers, and has a measured noise figure (NF) $ 7 dB up to 88.5 GHz, 800 mVpp of linear input range, and 8.5 dB gain. Operation was confirmed with PRBS-31 eye diagram measurements up to 120 Gb/s. Additionally, a novel time-interleaved distributed power DAC test circuit was implemented as a proof-of-concept to investigate the maximum achievable output bandwidth at a differential output voltage swing of 6 Vpp, as needed to directly drive an optical modulator. Simulations of the doubly segmented 6-bit DAC show 4-PAM output eye diagrams at up to 120 GBaud. The measured clock-input-to-data-output small-signal bandwidth is 65 GHz. When the DAC is measured as a switching large-swing driver, the differential output voltage swing remains larger than $5.4~\text {V}_{\mathrm {pp}}$ beyond 50 Gb/s. Time interleaving of 4 thermometer MSBs is demonstrated experimentally to form a 1.8- $\text{V}_{\text {pp}}$ differential, 10-GBaud 3-PAM output signal. The experimental sampling rate is limited to 10 GS/s by the capacitance and bandwidth of the low-frequency probes and pads used for the data lanes.

Fabrication and Characterization of Polymer-Enhanced TSVs, Inductors, and Antennas for Mixed-Signal Silicon Interposer Platforms

This paper demonstrates the fabrication and high-frequency characterization of polymer-enhanced technologies for a mixed-signal silicon interposer platform. First, the fabrication of 60- $\mu \text{m}$ -diameter and 285- $\mu \text{m}$ -tall photodefined polymer-embedded vias is demonstrated. Their losses are extracted using L–2L and open–short de-embedding techniques up to 30 GHz followed by parasitics extraction. Moreover, eye-diagram measurements are demonstrated for the vias at 10 Gb/s. Second, the fabrication and impedance extraction of 65- $\mu \text{m}$ -diameter and 285- $\mu \text{m}$ -tall photodefined polymer-enhanced coaxial vias are demonstrated. Finally, utilizing the photodefined polymer-enhanced silicon interposer technology, high-performance inductor and antenna are demonstrated over polymer wells.

High speed BiCMOS linear driver core for segmented InP Mach-Zehnder modulators

A hybrid arrangement for an optical transmitter sub-system comprising a linear driver fabricated in IHP SiGe 0.13 µm BiCMOS technology with an InP segmented Mach-Zehnder modulator is described. The proposed scheme, with direct interface to the digital to analog converter, is suitable for coherent high order modulation formats intended for data transmission over optical fiber at a wavelength of 1550 nm. In this paper, a partial prototype, consisting of a single driver core and modulator segment is demonstrated. The driver core features an output differential voltage of 2.5 Vpp, a gain of 9 dB and a 3 dB bandwidth of 32 GHz. Linearity is evaluated through total harmonic distortion measurements. With on---off-keying modulation, electro-optical eye diagram measurements of the single segment demonstrate successful operation up to 40 Gb/s data rate. While exhibiting clear capability for high speed operation, these results serve also to explore the boundaries of the proposed hybrid configuration.

Experimental evaluation of electrical properties of fabrics elaborated with conductive yarns

In this paper, the electrical characterization of two different fabric structures elaborated with conductive yarns and several pick densities are investigated in order to evaluate their electrical properties as conductive media of digital electrical signals. The real and imaginary impedance and the signal integrity have been measured for each e-textile. The results show that the impedance depends on the fabric structures and pick density. The eye diagram measurements experimentally demonstrate the functionality of these fabrics to transmit digital electric signals to communicate sensors with microcontrollers in wearable applications.