A Low‐Crosstalk Design of 1.25 Gbps Optical Triplexer Module for FTTH Systems

In this paper, we analyzed and measured the electrical crosstalk characteristics of a 1.25 Gbps triplexer module for Ethernet passive optical networks to realize fiber‐to‐the‐home services. Electrical crosstalk characteristic of the 1.25 Gbps optical triplexer module on a resistive silicon substrate should be more serious than on a dielectric substrate. Consequently, using the finite element method, we analyze the electrical crosstalk phenomena and propose a silicon substrate structure with a dummy ground line that is the simplest low‐crosstalk layout configuration in the 1.25 Gbps optical triplexer module. The triplexer module consists of a laser diode as a transmitter, a digital photodetector as a digital data receiver, and an analog photodetector as a cable television signal receiver. According to IEEE 802.3ah and ITU‐T G.983.3, the digital receiver and analog receiver sensitivities have to meet ‐24 dBm at BER=10^?12 and ‐7.7 dBm at 44 dB SNR. The electrical crosstalk levels have to maintain less than ‐86 dB from DC to 3 GHz. From analysis and measurement results, the proposed silicon substrate structure that contains the dummy line with 100 μm space from the signal lines and 4 mm separations among the devices satisfies the electrical crosstalk level compared to a simple structure. This proposed structure can be easily implemented with design convenience and greatly reduce the silicon substrate size by about 50 %.     

Right‐Angle‐Bent CPW for the Application of the Driver‐Amplifier‐Integrated 40 Gbps TW‐EML Module

In this letter we present a right‐angle‐bent coplanar waveguide (CPW) which we developed for the application of the driver amplifier‐integrated (DAI) 40 Gbps traveling wave electroabsorption modulated laser module. The developed CPW realized parallel progression of the radio frequency (RF) and light using a dielectric overlay structure and wedge bonding on the bending section. The measured S₁₁ and S₂₁ of the developed CPW were kept below ?10 dB up to 35 GHz and ?3 dB up to 43 GHz, respectively. These measured results of the CPW were in good agreement with the simulation results and demonstrated the applicability of the CPW to the 40 Gbps communication module.     

27-GHz bandwidth high-speed monolithic integrated optoelectronicphotoreceiver consisting of a waveguide fed photodiode and anInAlAs/InGaAs-HFET traveling wave amplifier

A monolithic integrated photoreceiver for 1.55-μm wavelength has been designed for operation in a 20-Gb/s synchronous digital hierarchy system (SDH/SONET), based on a new integration concept. The optoelectronic integrated circuit (OEIC) receiver combines a waveguide-integrated PIN-photodiode and a traveling wave amplifier in coplanar waveguide layout with four InAlAs/InGaAs/InP-HFETs (0.7-μm gate length). The receiver demonstrates a bandwidth of 27 GHz with a low frequency transimpedance of 40 dBΩ. This is, to our knowledge, the highest bandwidth ever reported for a monolithic integrated photoreceiver on InP. Furthermore, a receiver sensitivity of -12 dBm in the fiber (20 Gb/s, BER=10^-9) and an overall optical input dynamic range of 27 dB is achieved. Optical time domain multiplex (TDM) system experiments of the receiver packaged in a module show an excellently shaped eye pattern for 20 Gb/s and an overall sensitivity of -30.5 dBm (BER=10^-9) [including erbium doped fiber amplifiers (EDFA)]     

High-speed photoreceivers using solder bumps and microstrip linesformed on a silicon optical bench

High-speed photoreceiver modules using silicon optical benches are described. These modules employ solder bumps for chip assembly and microstrip lines for electrical signal transmission. The assembly and wiring technologies are the same as those used in the planar lightwave circuit platforms we developed. A photoreceiver module consisting of a waveguide photodiode showed a very wide bandwidth greater than 20 GHz, and together with a spotsize-converted semiconductor optical amplifier, operated as an optical preamplifier that showed good receiver sensitivity of -20.3 dBm at 10 Gb/s nonreturn-to-zero     

High performance modules of 2.5 Gbps modulator integrated DFBlasers using new RF impedance matching technique

We report the improvement of frequency response characteristics of 2.5 Gbps modulator integrated distributed feedback (MI-DFB) laser modules using new impedance matching technique. Frequency responses for the fabricated module using the `+' shaped microstrip line for impedance matching have been significantly improved such as the RF return loss of 11 dB and the 3 dB frequency bandwidth of 4.1 GHz, compared to 6 dB return loss and 1.5 GHz bandwidth for the conventional module. These results can also be predicted by the simulation of frequency responses for the modules, From the fabricated MI-DFB laser modules, good transmission performance has been obtained up to 640 km     

InP基长波长单片集成光接收前端的设计和制备

叙述了利用InP基长波长pin光探测器和异质结双极晶体管(HBT)单片集成实现光接收前端的设计和制备方法.pin光探测器和HBT采用共享层结构,这样的结构不仅性能优于堆叠层结构,而且制备工艺兼容.制备的HBT截止频率达到30GHz,pin光探测器的3dB带宽达到了15GHz,集成光接收前端的3dB带宽达到3GHz,跨阻放大倍数达到800.     

8-element linear array monolithic p-i-n MODFET photoreceivers usingmolecular beam epitaxial regrowth

An 8-element linear array of single-stage integrating front-end photoreceivers using molecular beam epitaxial (MBE) regrowth was investigated. Each element consisted of a p-i-n In_0.53Ga_0.47As photodiode integrated with a selectively regrown pseudomorphic In_0.65Ga_0.35As/In_0.52Al_0.48 As MODFET. Cutoff frequencies of 1.0-μm discrete regrown MODFETs were f_t=24 GHz and f_max=50 GHz. Transconductance of the regrown MODFETs was as high as 495 mS/mm with a current density (I_ds) of 250 mA/mm. The 3-dB bandwidth of the photoreceiver was measured to be 1 GHz. The bit rate sensitivity at 1 Gb/s was -31.8 dBm for BER 10^-9 using 1.55 μm excitation for a photoreceiver with an anti-reflection coating. The single-stage amplifier exhibited up to 25 dB flatband gain of the photocurrent, and a two-stage amplifier was up to 31 dB of gain. Good uniformity between each photoreceiver element in the array was achieved. Electrical crosstalk between photoreceiver elements was estimated to be ~-34 dB     

Demonstration of CSRZ Signal Generator Using Single‐Stage Mach‐Zehnder Modulator and Wideband CMOS Signal Mixer

In this paper, we demonstrate an electrically band‐limited carrier‐suppressed return‐to‐zero (EB‐CSRZ) signal generator operating up to a 10 Gbps data rate comprising a single‐stage Mach‐Zehnder modulator and a wideband signal mixer. The wideband signal mixer comprises inverter stages, a mixing stage, and a gain amplifier. It is implemented by using a 0.13 μm CMOS technology. Its transmission response shows a frequency range from DC to 6.4 GHz, and the isolation response between data and clock signals is about 21 dB at 6.4 GHz. Experimental results show optical spectral narrowing due to incorporating an electrical band‐limiting filter and some waveform distortion due to bandwidth limitation by the filter. At 10 Gbps transmission, the chromatic dispersion tolerance of the EB‐CSRZ signal is better than that of NRZ‐modulated signal in single‐mode fiber.     

40 Gbps All‐Optical 3R Regeneration and Format Conversion with Related InP‐Based Semiconductor Devices

We report an experimental demonstration of 40 Gbps all‐optical 3R regeneration with all‐optical clock recovery based on InP semiconductor devices. We also obtain all optical non‐return‐to‐zero to return‐to‐zero (NRZ‐to‐RZ) format conversion using the recovered clock signal at 10 Gbps and 40 Gbps. It leads to a good performance using a Mach‐Zehnder interferometric wavelength converter and a self‐pulsating laser diode (LD). The self‐pulsating LD serves a recovered clock, which has an rms timing jitter as low as sub‐picosecond. In the case of 3R regeneration of RZ data, we achieve a 1.0 dB power penalty at 10^?9 BER after demultiplexing 40 Gbps to 10 Gbps with an eletro‐absorption modulator. The regenerated 3R data shows stable error‐free operation with no BER floor for all channels. The combination of these functional devices provides all‐optical 3R regeneration with NRZ‐to‐RZ conversion.     

16‐QAM OFDM‐Based W‐Band Polarization‐Division Duplex Communication System with Multi‐gigabit Performance

This paper presents a novel 90 GHz band 16‐quadrature amplitude modulation (16‐QAM) orthogonal frequency‐division multiplexing (OFDM) communication system. The system can deliver 6 Gbps through six channels with a bandwidth of 3 GHz. Each channel occupies 500 MHz and delivers 1 Gbps using 16‐QAM OFDM. To implement the system, a low‐noise amplifier and an RF up/down conversion fourth‐harmonically pumped mixer are implemented using a 0.1‐μm gallium arsenide pseudomorphic high‐electron‐mobility transistor process. A polarization‐division duplex architecture is used for full‐duplex communication. In a digital modem, OFDM with 256‐point fast Fourier transform and (255, 239) Reed‐Solomon forward error correction codecs are used. The modem can compensate for a carrier‐frequency offset of up to 50 ppm and a symbol rate offset of up to 1 ppm. Experiment results show that the system can achieve a bit error rate of 10^–5 at a signal‐to‐noise ratio of about 19.8 dB.     

16‐QAM‐Based Highly Spectral‐Efficient E‐band Communication System with Bit Rate up to 10 Gbps

This paper presents a novel 16‐quadrature‐amplitude‐modulation (QAM) E‐band communication system. The system can deliver 10 Gbps through eight channels with a bandwidth of 5 GHz (71‐76 GHz/81‐86 GHz). Each channel occupies 390 MHz and delivers 1.25 Gbps using a 16‐QAM. Thus, this system can achieve a bandwidth efficiency of 3.2 bit/s/Hz. To implement the system, a driver amplifier and an RF up‐/down‐conversion mixer are implemented using a 0.1 µm gallium arsenide pseudomorphic high‐electron‐mobility transistor (GaAs pHEMT) process. A single‐IF architecture is chosen for the RF receiver. In the digital modem, 24 square root raised cosine filters and four (255, 239) Reed‐Solomon forward error correction codecs are used in parallel. The modem can compensate for a carrier‐frequency offset of up to 50 ppm and a symbol rate offset of up to 1 ppm. Experiment results show that the system can achieve a bit error rate of 10^?5 at a signal‐to‐noise ratio of about 21.5 dB.     

A 12-Gb/s high-performance, high-sensitivity monolithic p-i-n/HBTphotoreceiver module for long-wavelength transmission systems

A very high sensitivity, high speed, fiber-pigtailed photoreceiver module is described. The OEIC photoreceiver, composed of a p-i-n photodetector monolithically integrated with an InP-InGaAs heterojunction bipolar transistor (HBT)-based transimpedance amplifier, has measured sensitivity of -20 dBm and -17.6 dBm for data rates of 10 and 12 Gb/s, respectively, at a bit error rate of 1×10^-9. These results are the best ever reported for an OEIC photoreceiver at these speeds. In an optical transmission experiment with a low noise erbium-doped fiber amplifier (EDFA) preceding the OEIC photoreceiver, the measured sensitivities were -35.2 and -32 dBm at 10 and 12 Gb/s respectively     

Adaptive predistortion of COFDM signals for a mobile satellite channel

In this paper, we consider the optimization of the performance of QPSK and 16‐QAM coded orthogonal frequency division multiplexing (COFDM) signals over the non‐linear and mobile satellite channel. A high power amplifier and Rician flat fading channel produces non‐linear and linear distortions; an adaptive predistortion technique combined with turbo codes will reduce both types of distortion. The predistorter is based on a feedforward neural network, with the coefficients being derived using an extended Kalman filter (EKF). The conventional turbo code is used to mitigate Rician flat fading distortion and Gaussian noise. The performance over a non‐linear satellite channel indicates that QPSK COFDM followed by a predistorter provides a gain of about 1.7 dB at a BER of 3×10^?3 when compared to QPSK COFDM without the predistortion scheme and 16‐QAM COFDM provides a gain of 0.5 dB output back‐off and 1.2 dB signal to noise ratio at a BER of 3×10^?5 when compared with an adaptive predistorter based on the Harmmerstein model. We also investigate the influence of the guard time interval and Doppler frequency effect on the BER performance. When the guard interval increases from 0 to 0.125T samples and the normalized Doppler frequency is 0.001, there is a gain of 0.7 and 1 dB signal to noise ratio at a BER of 6×10^?4 for QPSK and 16‐QAM COFDM, respectively. Copyright © 2003 John Wiley & Sons, Ltd.     

A 20 Gbps inductorless CMOS optical receiver for short-distance VCSEL-based 850 nm optical links

This paper presents a circuit design and experimental results for a 20 Gbps CMOS inductorless optical receiver, a transimpedance amplifier (TIA) and a limiting amplifier, for a vertical-cavity surface emitting laser based 850 nm optical link. The proposed optical receiver apply a power supply noise canceling technique, an additional path from the power supply to the TIA output to generate a reversed phase signal that reduces the power supply noise, and bandwidth enhancement circuit design that dose not require internal inductors. The simulation results shows a power supply rejection ratio of ?96.6 dB at 10 MHz, a total gain of $82.8\,\hbox{dB}\Upomega$ and a ?3 dB bandwidth of 15.5 GHz. A test chip fabricated in 90 nm CMOS technology and demonstrated with a PIN photo-diode, a bandwidth of 17 GHz and a responsibility of 0.53 A/W. The measurement results show a 25 % eye opening and an input sensitivity of ?7.1 dBm at a bit error rate of 10^?12 with a 2⁹ ? 1 pseudo-random test pattern at 20 Gbps. The core circuit of the optical receiver occupies only an area of 0.02 mm².     

A design technique for a 60 GHz-bandwidth distributed basebandamplifier IC module

A DC-60 GHz, 9 dB distributed amplifier IC module is fabricated with 0.15 μm InAlAs-InGaAs low-noise HEMTs with 155 GHz f_T and 234 GHz f_max. The device is mounted in a metal package with 1.8 mm coaxial cable signal interfaces. The package is specially designed using three-dimensional electromagnetic field analyses, resulting in very flat frequency characteristics of the module within 1.5 dB gain ripples over the entire bandwidth. A multichip module loaded with two amplifier ICs in cascade is also fabricated, and operates at a 17.5 dB gain from 60 kHz to 48 GHz. The 1 dB gain compression output power is about 5 dBm for both modules. The noise figure of the single-chip module is approximately 4 dB over a 10-40 GHz frequency range     

7.1 GHz bandwidth monolithically integratedIn0.53Ga0.47As/In0.52Al0.48As PIN-HBT transimpedance photoreceiver

A monolithically integrated photoreceiver using an InAlAs/InGaAs HBT-based transimpedance amplifier has been fabricated and characterized. The p-i-n photodiode is implemented using the base-collector junction of the HBT. The 5 μm×5 μm emitter area transistors have self-aligned base metal and non-alloyed Ti/Pt/Au contacts. Discrete transistors demonstrated f_T and f_max of 54 GHz and 51 GHz, respectively. The amplifier demonstrated a -3 dB transimpedance bandwidth of 10 GHz and a gain of 40 dBΩ. The integrated photoreceiver with a 10 μm×10 μm p-i-n photodiode showed a -3 dB bandwidth of 7.1 GHz     

2500 km-10 Gbps RZ transmission system based on dispersion compensation CFBGs without electric regenerator

The characteristics of chirped fiber Bragg gratings (CFBGs) are optimized so that the ripple coefficient of the power reflectivity spectrum and group time delay are less than 1 dB and |± 15| ps, group delay is about 2600 ps/nm, polarization module dispersion is very small, PMD<2 ps, -3 dB bandwidth is about 0.35 nm, and insertion loss is about 4-5 dBm. Using dispersion compensation CFBG, a 2500 km-10 Gbps RZ optical signal transmission system on G.652 fiber was successfully demonstrated without an electric regenerator by optimizing dispersion management and loss management. The RZ optical signal was generated through a two-stage modulation method. At 2081 km, the power penalty of transmission is about 3 dB (conditions: RZ signal, BER = 10-12, PRBS = 1023 - 1); At 2560 km, the power penalty is about 5 dB. It is superior to the system using NRZ under the same conditions.     

Analog CMOS design for optical coherence tomography signal detection and processing.

A CMOS circuit was designed and fabricated for optical coherence tomography (OCT) signal detection and processing. The circuit includes a photoreceiver, differential gain stage and lock-in amplifier based demodulator. The photoreceiver consists of a CMOS photodetector and low noise differential transimpedance amplifier which converts the optical interference signal into a voltage. The differential gain stage further amplifies the signal. The in-phase and quadrature channels of the lock-in amplifier each include an analog mixer and switched-capacitor low-pass filter with an external mixer reference signal. The interferogram envelope and phase can be extracted with this configuration, enabling Doppler OCT measurements. A sensitivity of -80 dB is achieved with faithful reproduction of the interferometric signal envelope. A sample image of finger tip is presented.     

Monolithically integrated multichannel SiGe/Si p-i-n-HBTphotoreceiver arrays

A low-power, short-wavelength eight-channel monolithically integrated photoreceiver array, based on SiGe/Si heterojunction bipolar transistors, is demonstrated. The photoreceiver consists of a photodiode, three-stage transimpedance amplifier, and passive elements for feedback, biasing and impedance matching. The photodiode and transistors are grown by molecular beam epitaxy in a single step. The p-i-n photodiode exhibits a responsivity of 0.3A/W and a bandwidth of 0.8 GHz at λ=0.88 μm. The three-stage transimpedance amplifier demonstrates a transimpedance gain of 43 dBΩ and a -3 dB bandwidth of 5.5 GHz. A single channel monolithically integrated photoreceiver consumes a power of 6 mW and demonstrates an optical bandwidth of 0.8 GHz. Eight-channel photoreceiver arrays are designed for massively parallel applications where low power dissipation and low crosstalk are required. The array is on a 250-μm pitch and can be easily scaled to much higher density. Large signal operation up to 1 Gb/s is achieved with crosstalk less than -26 dB. A scheme for time-to-space division multiplexing is proposed and demonstrated with the photoreceiver array     

Monolithically integrated long wavelength photoreceiver OEIC based on InP/InGaAs HBT technology

The epitaxial structure and growth, circuit design, fabrication process and characterization are described for the photoreceiver opto-electronic integrated circuit (OEIC) based on the InP/lnGaAs HBT/PIN photodetector integration scheme. A 1.55 μm wavelength monolithically integrated photoreceiver OEIC is demonstrated with self-aligned InP/lnGaAs heterojunction bipolar transistor (HBT) process. The InP/lnGaAs HBT with a 2 μm × 8 μm emitter showed a DC gain of 40, a DC gain cutoff frequency of 45 GHz and a maximum frequency of oscillation of 54 GHz. The integrated InGaAs photodetector exhibited a responsivity of 0.45 AAV at λ = 1.55 μm, a dark current less than 10 nA at a bias of -5 V and a -3 dB bandwidth of 10.6 GHz. Clear and opening eye diagrams were obtained for an NRZ 223-l pseudorandom code at both 2.5 and 3.0 Gbit/s. The sensitivity for a bit error ratio of 10-9 at 2.5 Gbit/s is less than -15.2 dBm.