A Cost‐Effective 40‐Gb/s ROSA Module Employing Compact TO‐CAN Package

In this paper, we present an implemented serial 40‐Gb/s receiver optical subassembly (ROSA) module by employing a proposed TO‐CAN package and flexible printed circuit board (FPCB). The TO‐CAN package employs an L‐shaped metal support to provide a straight line signal path between the TO‐CAN package and the FPCB. In addition, the FPCB incorporates a signal line with an open stub to alleviate signal distortion owing to an impedance mismatch generated from the soldering pad attached to the main circuit board. The receiver sensitivity of the ROSA module measures below –9 dBm for 40 Gb/s at an extinction ratio of 7 dB and a bit error rate of 10^?12.     

A 40 Gb/s Clock and Data Recovery Module with Improved Phase‐Locked Loop Circuits

A 40 Gb/s clock and data recovery (CDR) module for a fiber‐optic receiver with improved phase‐locked loop (PLL) circuits has been successfully implemented. The PLL of the CDR module employs an improved D‐type flip‐flop frequency acquisition circuit, which helps to stabilize the CDR performance, to obtain faster frequency acquisition, and to reduce the time of recovering the lock state in the event of losing the lock state. The measured RMS jitter of the clock signal recovered from 40 Gb/s pseudo‐random binary sequence (2³¹‐1) data by the improved PLL clock recovery module is 210 fs. The CDR module also integrates a 40 Gb/s D‐FF decision circuit, demonstrating that it can produce clean retimed data using the recovered clock.     

Fabrication and Characteristics of 40-Gb/s Traveling-Wave Electroabsorption Modulator-Integrated DFB Laser Modules

We have developed 40-Gb/s traveling-wave electroabsorption-modulator-integrated distributed feedback laser (TW-EML) modules using several advanced technologies. First, we have adopted a selective area growth (SAG) method in the fabrication of the 40-Gb/s EML device to provide active layers for the laser and the electroabsorption modulators (EAMs) simultaneously. The fabricated device shows that the measured 3-dB bandwidth of electrical-to-optical (E/O) response reaches about 45 GHz and the return loss (S₁₁) is kept below -10 dB up to 50 GHz. For the module design of the device, we mainly considered electrical and optical factors. The measured S₁₁ of the fabricated 40 Gb/s TW-EML module is below -10 dB up to about 30 GHz and the 3-dB bandwidth of the E/O response reaches over 35 GHz. We also have developed two types of coplanar waveguide (CPW) for the application of the driver amplifier integrated 40 Gb/s TW-EML module, which is a system-on-package (SoP) composed of an EML device and a driver amplifier device in a module. The measured S₁₁ of the two-step-bent CPW is below -10 dB up to 35 GHz and the measured S₁₁ of the parallel type CPW is below -10 dB up to 39 GHz.     

Cost‐Effective Transition to 40 Gb/s Line Rate Using the Existing 10 Gb/s‐Based DWDM Infrastructure

In this paper, we propose and demonstrate a cost‐effective technique to upgrade the capacity of dense wavelength division multiplexing (DWDM) networks to a 40 Gb/s line rate using the existing 10 Gb/s‐based infrastructure. To accommodate 40 Gb/s over the link optimized for 10 Gb/s, we propose applying a combination of super‐FEC, carrier‐suppressed return‐to‐zero, and pre‐emphasis to the 40 Gb/s transponder. The transmission of 40 Gb/s DWDM channels over existing 10 Gb/s line‐rate long‐haul DWDM links, including 40×40 Gb/s transmission over KT's standard single‐mode fiber optimized for 10 Gb/s achieves successful results. The proposed upgrading technique allows the Q‐value margin for a 40 Gb/s line rate to be compatible with that of 10 Gb/s.     

Design and Implementation of Open‐Loop Clock Recovery Circuit for 39.8 Gb/s and 42.8 Gb/s Dual‐Mode Operation

This paper proposes an open‐loop clock recovery circuit (CRC) using two high‐Q dielectric resonator (DR) filters for 39.8 Gb/s and 42.8 Gb/s dual‐mode operation. The DR filters are fabricated to obtain high Q‐values of approximately 950 at the 40 GHz band and to suppress spurious resonant modes up to 45 GHz. The CRC is implemented in a compact module by integrating the DR filters with other circuits in the CRC. The peak‐to‐peak and RMS jitter values of the clock signals recovered from 39.8 Gb/s and 42.8 Gb/s pseudo‐random binary sequence (PRBS) data with a word length of 2³¹?1 are less than 2.0 ps and 0.3 ps, respectively. The peak‐to‐peak amplitudes of the recovered clocks are quite stable and within the range of 2.5 V to 2.7 V, even when the input data signals vary from 150 mV to 500 mV. Error‐free operation of the 40 Gb/s‐class optical receiver with the dual‐mode CRC is confirmed at both 39.8 Gb/s and 42.8 Gb/s data rates.     

10 Gb/s电吸收调制器的微波封装设计

在高速光电子器件的微波封装过程中，需要综合考虑封装寄生参数和芯片寄生参数对器件高频性能的影响。利用封装寄生参数对芯片寄生参数的补偿作用，成功实现了10Gb／s电吸收调制激光器（EML）的高频封装。通过封装前后芯片和器件的小信号频率响应测试结果对比，器件的反射参数和传输参数有所改善，3dB带宽达到10GHz；并进行了10Gb／s速率的光纤传输实验，经过40km光纤传输后通道代价不到1dBm（误码率为10^-12），满足10Gb／s长距离光纤传输系统的要求。     

Compact 2.5 Gb/s Burst‐Mode Receiver with Optimum APD Gain for XG‐PON1 and GPON Applications

This letter presents a compact 2.5 Gb/s burst‐mode receiver using the first reported monolithic amplifier IC developed with 0.25 …m SiGe BiCMOS technology. With optimum avalanche photodiode gain, the receiver module can obtain a fast response, high sensitivity and wide dynamic range, satisfying the overhead timing and various power specifications for a 2.5 Gb/s next‐generation passive optical network (PON), as well as a legacy 1.25 Gb/s PON in the upstream.     

Fabrication of 40 Gb/s Front‐End Optical Receivers Using Spot‐Size Converter Integrated Waveguide Photodiodes

We fabricated 40 Gb/s front‐end optical receivers using spot‐size converter integrated waveguide photodiodes (SSC‐WGPDs). The fabricated SSC‐WGPD chips showed a high responsivity of approximately 0.8 A/W and a 3 dB bandwidth of approximately 40 GHz. A selective wet‐etching method was first adopted to realize the required width and depth of a tapered waveguide. Two types of electrical pre‐amplifier chips were used in our study. One has higher gain and the other has a broader bandwidth. The 3 dB bandwidths of the higher gain and broader bandwidth modules were about 32 and 42 GHz, respectively. Clear 40 Gb/s non‐return‐to‐zero (NRZ) eye diagrams showed good system applicability of these modules.     

Design of a Cost‐Effective Hybrid‐Type PBEx Providing a High Power Budget in an Asymmetric 10G‐EPON

This paper proposes a cost‐effective hybrid‐type power budget extender (PBEx) that can provide a high power budget of over 45 dB in an asymmetric 10‐Gb/s Ethernet passive optical network (10/1G‐EPON). The hybrid‐type 10/1G‐EPON PBEx comprises a central office terminal (COT) and remote terminal (RT) module supporting four channels and uses a coarse wavelength division multiplexing (CWDM) technology between the COT and RT for a reduction of fiber cost and efficient access network design. The proposed 10/1G‐EPON PBEx can provide over a 40‐km reach and 128‐way split per CWDM wavelength with no modification of a legacy 10/1G‐EPON system and can satisfy the error‐free service in 10¹⁰ packet transmission.     

Fabrication of Transimpedance Amplifier Module and Post‐Amplifier Module for 40 Gb/s Optical Communication Systems

The design and performance of an InGaAs/InP transimpedance amplifier and post amplifier for 40 Gb/s receiver applications are presented. We fabricated the 40 Gb/s transimpedance amplifier and post amplifier using InGaAs/InP heterojunction bipolar transistor (HBT) technology. The developed InGaAs/InP HBTs show a cut‐off frequency (f_T) of 129 GHz and a maximum oscillation frequency (f_max) of 175 GHz. The developed transimpedance amplifier provides a bandwidth of 33.5 GHz and a gain of 40.1 dBΩ. A 40 Gb/s data clean eye with 146 mV amplitude of the transimpedance amplifier module is achieved. The fabricated post amplifier demonstrates a very wide bandwidth of 36 GHz and a gain of 20.2 dB. The post‐amplifier module was fabricated using a Teflon PCB substrate and shows a good eye opening and an output voltage swing above 520 mV.     

Physical Media Dependent Prototype for 10‐Gigabit‐Capable PON OLT

In this work, we study the physical layer solutions for 10‐gigabit‐capable passive optical networks (PONs), particularly for an optical link terminal (OLT) including a 10‐Gbit/s electroabsorption modulated laser (EML) and a 2.5‐Gbit/s burst mode receiver (BM‐Rx) in a novel bidirectional optical subassembly (BOSA). As unique features, a bidirectional mini‐flat package and a 9‐pin TO package are developed for a 10‐gigabit‐capable PON OLT BOSA composed of a 1,577‐nm EML and a 1,270‐nm avalanche photodiode BM‐Rx, including a single‐chip burst mode integrated circuit that is integrated with a transimpedance and limiting amplifier. In the developed prototype, the 10‐Gbit/s transmitter and 2.5‐Gbit/s receiver characteristics are evaluated and compared with the physical media dependent (PMD) specifications in ITU‐T G.987.2 for XG‐PON1. By conducting the 10‐Gbit/s downstream and 2.5‐Gbit/s upstream transmission experiments, we verify that the developed 10‐gigabit‐capable PON PMD prototype can operate for extended network coverage of up to a 40‐km fiber reach.     

Pseudo Optical PAM‐N Signal Using Externally Modulated Lasers

We propose a pseudo optical N‐level pulse‐amplitude modulation (PO PAM‐N) signal using a few externally‐modulated lasers (EMLs) operating at different wavelengths, which is suitable for upgrading the transmission speed over an optical link of ＜ 10 km single‐mode fiber with low‐cost components. To compare a PO PAM‐N signal with that of a standard optical PAM‐N signal, we perform experiments for evaluating the performance of a 51.56‐Gb/s PO PAM‐4 signal and standard 51.56‐Gb/s optical PAM‐4 signal. The receiver sensitivity (at ) of the PO PAM‐4 signal is 1.5 dB better than the receiver sensitivity of a standard optical PAM‐4 signal. We also investigate the feasibility of PO PAM‐N signals operating at 103.12 Gb/s, considering relative intensity noise, timing jitter, extinction ratio (ER) of EMLs, and dispersion. From the results, a PO PAM‐8 signal performs better than PO PAM‐4 and PO PAM‐16 signals at 103.12 Gb/s. Finally, we suggest a timing control method to suppress the effect of dispersion in a PO PAM‐N signal. We show that the tolerance to dispersion of a 103.12‐Gb/s PO PAM‐8 signal can be improved to ±40 ps/nm by applying a proposed scheme.     

Engineering Efficiency Roll‐Off in Organic Light‐Emitting Devices

Previous studies have identified triplet‐triplet annihilation and triplet‐polaron quenching as the exciton density‐dependent mechanisms which give rise to the efficiency roll‐off observed in phosphorescent organic light‐emitting devices (OLEDs). In this work, these quenching processes are independently probed, and the impact of the exciton recombination zone width on the severity of quenching in various OLED architectures is examined directly. It is found that in devices employing a graded‐emissive layer (G‐EML) architecture the efficiency roll‐off is due to both triplet‐triplet annihilation and triplet‐polaron quenching, while in devices which employ a conventional double‐emissive layer (D‐EML) architecture, the roll‐off is dominated by triplet‐triplet annihilation. Overall, the efficiency roll‐off in G‐EML devices is found to be much less severe than in the D‐EML device. This result is well accounted for by the larger exciton recombination zone measured in G‐EML devices, which serves to reduce exciton density‐driven loss pathways at high excitation levels. Indeed, a predictive model of the device efficiency based on the quantitatively measured quenching parameters shows the role a large exciton recombination zone plays in mitigating the roll‐off.     

10Gb/s EML-TOSA及其在中长距离光通信中的应用

介绍了10Gb/s EML-TOSA的工作原理、主要结构和性能;通过调测和比较,给出了EAM的“1”码电平和峰-峰调制电压最佳条件;分析、讨论了10Gb/s EML-TOSA的动态谱宽、眼图、色散容限和阻抗匹配等问题;指出了10Gb/s EML-TOSA具有动态谱宽较小,色散代价较小的特点,在中、长距离实用化光通信中将有广泛的应用.     

Exciton–Polaron‐Induced Aggregation of Wide‐Bandgap Materials and its Implication on the Electroluminescence Stability of Phosphorescent Organic Light‐Emitting Devices

The degradation mechanisms of phosphorescent organic light‐emitting devices (PhOLEDs) are studied. The results show that PhOLED degradation is closely linked to interactions between excitons and positive polarons in the host material of the emitter layer (EML), which lead to its aggregation near the EML/electron transport layer (ETL) interface. This exciton–polaron‐induced aggregation (EPIA) is associated with the emergence of new emission bands at longer wavelengths in the electroluminescence spectra of these materials, which can be detected after prolonged device operation. Such EPIA processes are found to occur in a variety of wide‐bandgap materials commonly used as hosts in PhOLEDs and are correlated with device degradation. Quite notably, the extent of EPIA appears to correlate with the material's bandgap rather than with the glass‐transition temperature. The findings uncover a new degradation mechanism, caused by polaron‐exciton interactions, that appears to be behind the lower stability of OLEDs utilizing wide‐bandgap materials in general. The same degradation mechanism can be expected to be present in other organic optoelectronic devices.     

High‐Transconductance Organic Thin‐Film Electrochemical Transistors for Driving Low‐Voltage Red‐Green‐Blue Active Matrix Organic Light‐Emitting Devices

Switching and control of efficient red, green, and blue active matrix organic light‐emitting devices (AMOLEDs) by printed organic thin‐film electrochemical transistors (OETs) are demonstrated. These all‐organic pixels are characterized by high luminance at low operating voltages and by extremely small transistor dimensions with respect to the OLED active area. A maximum brightness of ≈900 cd m^?2 is achieved at diode supply voltages near 4 V and pixel selector (gate) voltages below 1 V. The ratio of OLED to OET area is greater than 100:1 and the pixels may be switched at rates up to 100 Hz. Essential to this demonstration are the use of a high capacitance electrolyte as the gate dielectric layer in the OETs, which affords extremely large transistor transconductances, and novel graded emissive layer (G‐EML) OLED architectures that exhibit low turn‐on voltages and high luminescence efficiency. Collectively, these results suggest that printed OETs, combined with efficient, low voltage OLEDs, could be employed in the fabrication of flexible full‐color AMOLED displays.     

Selected area growth integrated wavelength converter based on PD-EAM optical logic gate

A selected area growth wavelength converter based on a PD-EAM optical logic gate for WDM application is presented, integrating an EML transmitter and a SOA-PD receiver. The design, fabrication, and DC characters were analyzed. A 2 Gb/s NRZ signal based on the C-band wavelength converted to 1555 nm with the highest extinction ratio of 7 dB was achieved and wavelength converted eye diagrams with eyes opened were presented.     

High‐Frequency Modeling and Optimization of E/O Response and Reflection Characteristics of 40 Gb/s EML Module for Optical Transmitters

A complete high‐frequency small‐signal circuit model of a 40 Gb/s butterfly electroabsorption modulator integrated laser module is presented for the first time to analyze and optimize its electro‐optic (E/O) response and reflection characteristics. An agreement between measured and simulated results demonstrates the accuracy and validity of the procedures. By optimizing the bonding wire length and the impedance of the coplanar waveguide transmission lines, the E/O response increases approximately 5% to 15% from 20 GHz to 33 GHz, while the signal injection efficiency increases from approximately 15% to 25% over 18 GHz to 35 GHz.     

Light harvesting photovoltaic mini‐generator

In this work, the design, fabrication and characterisation of a millimetre‐size photovoltaic (PV) energy source is described. The fabrication process is based on p‐type silicon‐on‐insulator wafers. It is shown that scaling up the number of cells from 9 to 169 makes the open‐circuit voltage to increase from 3.6 to 101.5 V with generated power densities ranging from 2.07 to 6.7 mW/cm² under 100 mW/cm² standard AM 1.5 Global Spectrum. A prototype consisting of a PV mini‐module connected to a mini‐battery has been assembled, modelled and characterised. The results show that the mini‐PV source can be used in low power applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Integration and Characteristics of 40-Gb/s Electroabsorption Modulator Integrated Laser Module With a Driver Amplifier and Bias Tees

Integration of a 40-Gb/s electroabsorption modulator integrated distributed feedback (DFB) laser (EML) module with a driver amplifier and bias tee was investigated. For the EML fabrication the selective area growth (SAG) technique was adopted for the first time. It is shown that, with the SAG technique, the 3-dB bandwidth of about 45 GHz was measured in the electrical to optical response, and the return loss (S11) of below $-$10 dB was achieved for up to 50 GHz . To integrate a bias tee within the module, a right-angle bent coplanar waveguide (CPW) was developed. The right-angle bent CPW was characterized with S11 of below $-$ 10 dB for up to 35 GHz and insertion loss (S21) of about $-$1.4 dB for up to 40 GHz . The whole integrated module including the EML, a driver amplifier, and bias tee was characterized under the conditions of an operating temperature of 25 $^{circ}{rm C}$, the modulator bias of 1.4 V, and the DFB laser current of 40 mA. S11 of below $-$10 dB was obtained for up to 14 GHz and the measured electrical-to-optical response has 3-dB bandwidth of about 20 GHz.