New hybrid integrated laser diode-drivers using microsolder bumpbonding: SPICE simulation of high-speed modulation characteristics

This paper proposes two types of new hybrid integrated laser diode (LD)-drivers that use microsolder bump bonding instead of conventional wire bonding. In one, an LD and a driver are flip-chip bonded to each other; in the other, an LD and a driver are flip-chip bonded onto a substrate. Their performances are compared to those of a monolithic LD-driver and a conventional hybrid one using wire bonding by a simulation program with integrated circuit emphasis (SPICE) with particular emphasis on high-speed LD modulation. The nonreturn-to-zero (NRZ) eye patterns modulated at signal speeds up to 30 Gb/s by the new hybrid integrated LD-drivers were hardly inferior to those by the monolithic LD-driver, whereas those by conventional hybrid ones were greatly degraded over 10 Gb/s. The new hybrid integrated LD-drivers are a feasible alternative to monolithic ones for high-speed optical transmitters     

0.14 THz 10 Gbps无线通信系统

太赫兹通信由于其固有的宽带特性,在Gbps以上的高速无线通信领域受到广泛关注。本文描述了一种工作在0.14 THz频段的无线通信系统,传输速率达10 Gbps。该系统基于超外差结构,中频采用数字信号处理技术进行16QAM高阶数字信号调制解调,依靠肖特基二极管次谐波混频技术实现从中频到太赫兹信号的频谱搬移。目前该系统已经通过了500 m 10 Gbps距离无线传输实验验证,通信频段为133.8 GHz～137.4 GHz,带宽3.6 GHz,发射功率0 dBm,传输误码率低于10-6。     

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.     

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.     

GHz级半导体激光器组件的设计与实现

本文报导了一种制备ZrO2高温快离子导体的新方法,使用连续CO2激光束在非平衡条件下熔凝CaO及MgO稳定的ZrO2快离子导体,激光作用时间只有几分钟。在室温至1000℃的范围内测量了样品的电导率,其结果与国外用常规方法制得的同类快离子导体的研究结果相当。     

倒装焊对探测器频响特性影响的理论分析及工艺优化

针对光探测器在倒装焊过程中频响性能恶化的问题,建立等效电路模型分析出其原因,并通过优化倒装焊工艺条件予以有效解决。该电路模型包括探测器芯片、过渡热沉和倒装焊环节三个部分。基于倒装焊后探测器的S11参数和频响曲线提取出倒装焊环节特征参数,确认焊点接触电阻过大是引起探测器频响下降的主要原因。通过优化倒装焊工艺条件,有效减小了焊点接触电阻,基本消除了倒装焊对探测器频响特性的影响。     

Performance improvement of 60‐GHz wireless optical systems with reverse‐parallel hybrid modulation scheme

This paper improves the performance of 60‐GHz wireless optical system including radio over fibre (RoF) and radio over free space optics (RoFSO), based on novel reverse‐parallel (RP) hybrid modulation scheme. This scheme combines the chromatic dispersion compensation technique of parallel modulation with energy efficiency manipulation technique of reverse modulation. Superior functioning of RoFSO is provided with reverse modulation compared with normal modulation. Comparative investigations are performed by loading 60‐GHz RF signal with 2.5 and 10‐Gbps data and modulating it with both reverse and hybrid modulators. Hybrid modulation performed better with improved BER of 10^?23 at distance of 51 km for 2.5‐Gbps data compared with reverse modulation with BER of 10^?7.     

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.     

High-performance traveling-wave electroabsorption modulators utilizing mushroom-type waveguide and periodic transmission line loading

For the first time, periodic loaded electrodes and mushroom-type waveguide are combined to improve the performance of traveling-wave electroabsorption modulators (TWEAMs) based on the asymmetric intra-step-barrier coupled double strained quantum well (AICD-SQW). The electrical modulation response of periodic mushroom-type TWEAM is obtained by using equivalent circuit model, and is compared with simulation result of conventional mushroom-type TWEAM counterpart. The equivalent circuit model simulation results indicate that for the exemplary modulation length of 300 mm, the mushroom-type TWEAM with periodic transmission line loading can achieve much wider bandwidth about 99.7 GHz and 43.1 GHz than the conventional counterpart with about 43 GHz and 33 GHz for 35 W and 45 W terminations, respectively.     

Optoelectronic and microwave transmission characteristics of indium solder bumps for low-temperature flip-chip applications

This paper describes low-temperature flip-chip bonding for both optical interconnect and microwave applications. Vertical-cavity surface-emitting laser (VCSEL) arrays were flip-chip bonded onto a fused silica substrate to investigate the optoelectronic characteristics. To achieve low-temperature flip-chip bonding, indium solder bumps were used, which had a low melting temperature of 156.7/spl deg/C. The current-voltage (I-V) and light-current (L-I) characteristics of the flip-chip bonded VCSEL arrays were improved by Ag coating on the indium bump. The I-V and L-I curves indicate that optical and electrical performances of Ag-coated indium bumps are superior to those of uncoated indium solder bumps. The microwave characteristics of the solder bumps were investigated by using a flip-chip-bonded coplanar waveguide (CPW) structure and by measuring the scattering parameter with an on-wafer probe station for the frequency range up to 40 GHz. The indium solder bumps, either with or without the Ag coating, provided good microwave characteristics and retained the original characteristic of the CPW signal lines without degradation of the insertion and return losses by the solder bumps.     

A Design Theory for Wide-Band Parametric Amplifiers

A new exact design theory for a nondegenerate parametric amplifier with double-tuned signal circuit and single-tuned idler circuit is described. If the resistance of the signal circuit, which is neglected in previous papers, is considered, there exists a frequency band in which the amplifier gain is positive. In this paper the band characteristics of the gain are related to this frequency band. Slope parameters of the idler and signal circuits are normalized by the slope parameters which are associated with the diode itself. These normalized slope parameters are used to relate the actual circuit and gain-bandwidth characteristics. The slope parameter of the external signal resonator is related to the negative slope parameter of the diode, and bounds on this ratio are given over which stable amplification is possible. A design table which gives the coupling ratio and slope parameter of the external signal resonator is derived by computer calculation. Experiments were made at 19 GHz. Positive-gain bandwidth was around 4.0 GHz, and flat bandwidth at 10-dB gain was 2.4 GHz. The ratio of these bandwidths coincided with the theory.     

一种复杂波形信号产生器的设计与实现

介绍了一种复杂波形信号产生器的设计与实现,采用高速直接数字频率合成器产生各种复杂波形信号,并且通过微波宽带倍频器对DDS产生的复杂波形信号进行倍频,从而实现对DDS输出信号带宽的扩展,最终产生各种宽带复杂波形信号。文中介绍了设计方案与实现方法,并研制出工程样机。最终设计的复杂波形信号产生器能够实现线性调频、非线性调频、相位编码等多种复杂波形信号,输出信号带宽最高可达1 GHz。     

基于混频偏置合成的高速太赫兹无线通信系统

提出一种基于载波抑制混频与载波偏置功率合成的高速太赫兹无线通信方案。发射端利用载波抑制混频器和载波偏置功率合成在140 GHz载波上实现了开关键控(OOK)调制;接收端利用包络检波接收器进行检波接收。分别开展了不同混频本振功率及偏置功率下的检波响应实验、不同基带信号功率及偏置功率下的检波响应实验,以及不同输入功率下的检波响应实验。实验结果对OOK调制器设计,以及OOK类通信系统的优化均具有较好的指导意义。最后,利用优化的系统参数在70 cm距离上实现了140 GHz, 16 Gbps的无线通信,系统误码率(BER)优于10-5。     

Dynamic properties of a 1.3 μm light-emission-and-detection(LEAD) diode with a high mesa semi-insulating BH for subscriber TCMtransmission

This paper describes the dynamic properties of a 1.3 μm light-emission-and-detection (LEAD) diode that has a high mesa semi-insulating buried heterostructure (SI-BH) to reduce the capacitance of the chip (0.6-0.8 pF). A modulation bandwidth of 12 GHz in laser diode (LD) operation and a detection bandwidth of about 2 GHz in photodetector (PD) operation are achieved using a chip and a module, respectively. In bit error rate (BER) performance at 30 Mb/s, a receiver sensitivity (BER=10^-8) of -40.2 dBm is confirmed, and switching characteristics of under 1 μs from LD to PD operation are estimated by circuit simulation     

实用化宽带半导体激光器组件的研制及其特性的研究

使用ＤＣ－ＰＢＨ型激光二极管芯片，设计制作了实用化封装形式的宽带半导体激光器组件，在理论上和实验上研究了组件的封装模型、小信号频率调制特性和非线性失真，其光响应为３ｄＢ，带宽大于２ＧＨｚ．该器件可满足六次群光通信系统的带宽要求，也可用于ＧＨｚ级微波副载波光通信系统．     

A CMOS imaging diversity receiver for gigabit free-space optical MIMO

A 7-channel imaging diversity receiver based on current-summing is implemented in a 180 nm CMOS technology for broadband free-space optical (FSO) multi-input/multi-output (MIMO) communication. Each channel employs a low input-impedance current mirror (CM) as the input stage, which allows the implementation of direct current-summing for equal-gain combining (EGC). The summed current signal drives a second stage transimpedance amplifier (TIA) to generate the output voltage. Electrical characterization was performed using a photodiode emulation circuit and chip-on-board FR-4 assembly, demonstrating a total transimpedance gain of 62 dBΩ, −3 dB bandwidth of 1.2 GHz, and eye diagrams up to 2 Gb/s for 0.25 pF photodiode capacitance. The theoretical sensitivity of the imaging receiver is −16.8 dBm for a bit error rate (BER) of 10⁻⁹ at a photodetector responsivity of 0.4 A/W. The simulated power consumption for a single front-end amplifier circuit is 4.2 mW, and for the second stage TIA is 10.3 mW from a single 1.8 V supply. The diversity receiver is flip-chip compatible to enable hybrid integration to a custom InGaAs photodetector array.     

Dynamic properties of 1.3 μm semi-insulating-BHlight-emission-and-detection (LEAD)-diode module for subscriber TCMtransmission systems

The dynamic properties of a 1.3 μm light-emission-and-detection (LEAD)-diode module that has a high mesa semi-insulating buried heterostructure (SI-BH) to reduce the capacitance of the chip (0.6-0.8 pF) are described. A modulation bandwidth of 12 GHz in laser diode (LD) operation, and detection bandwidth of ~1.9 GHz in photodetector (PD) operation are achieved using a chip and a module, respectively. In bit error rate (BER) performance at 30 Mbit/s, a receiver sensitivity (BER=10^-8) of -37.4 dBm is confirmed, and a switching time of under 1 μs from LD to PD operation is estimated using a circuit simulator     

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 two-step etching technique for silica terraces in the PLC hybrid integration

Two-step etching, after the full processes of a silica waveguide, was performed to fabricate a silica-terraced planar lightwave circuit platform for the hybrid integration of optoelectronic devices. Spot-size converted distributed feedback laser diodes (SSC DFB LDs) were flip-chip bonded on silica terraces with the height accuracy of less than 1 /spl mu/m, and the resultant coupling loss between the SSC DFB LD and the silica waveguide was about 3.78 dB. The light-current curve of the LD flip-chip bonded on the platform showed the almost linear increase of the output power without any saturation.     

The flip-chip bump interconnection for millimeter-wave GaAs MMIC

The flip-chip bump interconnection structure has become popular for microwave and millimeter-wave package applications. This structure is expected to provide higher performance and a low cost packaging method. This paper presents the results of an evaluation of flip-chip assembled radio frequency (RF) devices. A coplaner transmission line type GaAs monolithic microwave integrated circuit (MMIC) was mounted on an aluminum oxide (Al₂O₃) substrate using the flip-chip thermal compression method. The electrical performance (S-parameter and noise figure) was measured and the reliability of the interconnection was tested. The changing rate of the characteristic impedance (Zo) of transmission line on bare-chip caused by bare-chip surface proximity to a substrate was simulated by finite element method (FEM) analysis. Flip-chip bonding conditions were fixed to keep the gap that less than 1% of Zo changing rate and sufficient bonding strength for reliability of interconnection. The DC characteristics of a 30 GHz, 60 GHz and 77 GHz band low noise amplifier (LNA) were the same before and after mounting, and the RF performance of the assembled MMIC was the same as the bare-chip without packaging. However, the influence of underfilling was observed. When epoxy resin was injected into the gap between the bare-chip and the substrate, the frequency band of the MMIC shifted to the low side. The reliability of the bump interconnection was excellent. The interconnection resistance did not change in a temperature cycle (-55°C to +125°C until 1500 cycle) test