GaAs/AlGaAs electro-optic modulator with bandwidth >40 GHz

A high speed GaAs/AlGaAs travelling wave Mach-Zehnder electro-optic modulator has been fabricated. The device uses a novel slow wave electrode design to achieve phase velocity matching and has a measured electrical bandwidth >40 GHz     

Generation of super-stable 40 GHz pulses from Fabry-Perot resonator integrated with electro-optic phase modulator

A simple technique for converting a continuous-wave laser beam into a stable pulse train with high repetition frequency is demonstrated. The generated train is based on the synthesis of its Fourier spectrum which is composed of higher-order sidebands produced by a Fabry-Perot resonator integrated with an electro-optic phase modulator. Super-stable 40 GHz, transform-limited optical pulses are successfully generated.     

A polymer electro-optic modulator with ultra wide-band and low driving voltage

In this paper, a polymer electro-optic modulator is designed and simulated using the full vectorial finite element method. First order edge elements are used in finite element implementation, and the finite element technique is used to obtain modulator response thoroughly. From the numerical analysis, frequency dispersions of modulator’s important parameters, such as microwave effective index nm , microwave characteristic impedance ZC and microwave loss a, are extracted. Our design exhibits elec...     

40 GHz, low half-wave voltage Ti:LiNbO/sub 3/ intensity modulator

A 5 V half-wave voltage (V/sub pi /) electro-optic Ti:LiNbO/sub 3/ intensity modulator with a -7.5 dB (electrical) optical response at 40 GHz is demonstrated at 1.3 mu m. A thick electrode structure is used in conjunction with a thin substrate to achieve a near optical-microwave phase match and a broadband electrical response.<>     

基于波状PN结的低驱动电压电光调制器

本文研究了一种基于波状PN结的低驱动电压电光调制器,该器件在光通信系统中可以获得较高的传输效率和较低的传输损耗。器件主要由光子晶体线缺陷波导和谐振腔组成。在光子晶体平板上下侧分别添加反向偏置电压,同时在波导中心区域引入谐振腔,通过在谐振腔区域添加不同浓度的掺杂,从而在线缺陷波导处形成波状PN结。根据等离子色散效应,在光子晶体两边施加反向偏置电压时会引起掺杂区硅基平板折射率的变化,从而导致光的透射率发生改变,以此达到调制的目的。采用时域有限差分法(FDTD)分析其时域稳态场强分布、模场分布和波状PN结参数对驱动电压的影响,结果表明:在驱动电压为1.04 V时,该器件可以实现中心波长为1 584.5 nm的TE模窄带宽通、断调制,且器件的消光比高达30.8 dB,插入损耗仅有0.5 dB,Q值高达1.4×10^4。     

40 GHz optical pulse generation using sinusoidally-driventravelling-wave electroabsorption modulator

Optical pulse generation at a 40 GHz repetition rate using a sinusoidally-driven high-modulation-efficiency travelling-wave electroabsorption modulator is reported. Travelling-wave behaviour is demonstrated by comparing the pulse generation in the co- and counter-propagation configurations and confirmed by a theoretical model     

40 Gbit/s n-i-n InP Mach-Zehnder modulator with a /spl pi/ voltage of 2.2 V

Using an n-i-n heterostructure, a travelling-wave Mach-Zehnder modulator on an InP substrate has been developed. An extremely small /spl pi/ voltage (V/sub /spl pi//) of 2.2 V has been obtained, even for a short signal-electrode length of 3 mm. Wavelength-insensitive extinction characteristics and 40 Gbit/s operation are described.     

A Ti:LiNbO/sub 3/ optical intensity modulator with more than 20 GHz bandwidth and 5.2 V driving voltage

A broadband and low driving-voltage Ti:LiNbO/sub 3/ optical intensity modulator is described. A coplanar waveguide with a shielding plane is used for optical-electrical velocity matching and a confined waveguide is used for lowering the driving voltage. The relationship between the mode size of the guided wave and the driving voltage is shown. This modulator has an electrical 3-dB bandwidth of more than 20 GHz and a driving voltage of 5.2 V at a wavelength of 1.5 mu m.<>     

1.3 V supply voltage 38 GHz static frequency divider

An ultra-low supply voltage and low power dissipation fully static frequency InP SHBT divider operating at up to 38 GHz is reported. The fully differential parallel current switched configuration of D-latch maintains the speed advantages of CML circuits while allowing full functionality at a very low supply voltage. The frequency divider operates at up to 38 GHz at a single-ended input power of 0 dBm. The power dissipation of the toggled D-flip-flop is 8 mW at a power supply voltage of 1.3 V. The authors believe this is the lowest supply voltage for static frequency dividers around this frequency in any technology. This low power configuration is suitable for any digital integrated circuit.     

5 V temperature regulated voltage reference

A 5 V internally temperature regulated voltage reference integrated circuit, which achieves 0.3 ppm//spl deg/C TC over the temperature range -55/spl deg/C to 125/spl deg/C, is described. It is built using a buried zener reference in a dielectrically isolated complementary bipolar process which employs laser trimmed NiCr thin film resistors and a high thermal resistance epoxy die attach.     

基于等离子体结构的太赫兹石墨烯电光调制器的机理分析

基于等离子体共振机理,提出了一种包含金属/石墨烯/Al2O3/石墨烯堆栈结构的等离子体脊型波导.基于光电效应的微观机理分析,通过设计波导结构和等离子体结构,优化调制器的性能.结果显示,电光调制器的插入损耗很低,工作在近红外波段,调制速率为730 GHz,能量损耗为0.7 fJ/bit,3-dB带宽为3.66 THz.     

Novel electrical squaring circuit with an output bandwidth from DCto 2·6 GHz

The author has proposed a novel squaring circuit consisting of two double-balanced mixers, with the first mixer serving as an upconverter and the second mixer performing the squaring function. Using commercially available mixers, an experimental squaring circuit was demonstrated with an output bandwidth from DC to 2·6 GHz and with over 30 dB suppression of the unsquared signal power relative to the squared signal power, for input signal powers from -5 to +3 dBm. This circuit is promising for electrical signal processing applications which require a DC-coupled squaring operation with bandwidths in excess of 1 GHz. One such application is in coherent optical phase diversity receivers     

0.2 μm AlSb/InAs HEMTs with 5 V gate breakdown voltage

DC and microwave measurements on AlSb/InAs HEMTs with a gate length of 0.21 μm are reported. The reverse gate characteristics exhibit relatively low gate leakage current and gate-drain breakdown voltages as high as 5 V. Equivalent circuit modelling yields an f_T of 110 GHz after removal of the gate bonding pad capacitance. The bias dependence of f_max is examined indicating a significant reduction in the unilateral gain due to impact ionisation     

A sub-40-ns chain FRAM architecture with 7-ns cell-plate-line drive

A nonvolatile chain FRAM adopting a new cell-plate-line drive technique was demonstrated. Two key circuit techniques, a two-way metal cell-plate line and a cell-plate line shared with 16 cells, reduce cell-plate-line delay to 7 ns and reduce plate drive area to 1/5. The total cell-plate-line delay, including cell transistor delay due to eight cells in series, is reduced to 15 μs, in contrast to 30-100-ns delay of the conventional FRAM. The die size is reduced to 86% that of the conventional FRAM by reduction of the plate driver area and sense amplifier area, assuming the same memory cell size. A prototype 16-kb chain FRAM chip was fabricated using 0.5 μm rule one-polycide and two-metal CMOS process. The memory cell size was 13.26 μm² using a 3.24-μm² capacitor. Thanks to the fast cell-plate-line drive, the chain FRAM test chip has achieved the fastest random access time, 37 ns, and read/write cycle time, 80 ns, at 3.3 V so far reported. The chain FRAM has also realized V_{dd min} of 2.3 V and 10¹⁰ read/write cycles     

30 GHz SiGe active inductor with voltage controlled Q

An active inductor (AI) based on a cascade gyrator for 30 GHz applications implemented with a 0.25 μm in SiGe technology is presented. The gyrator converts not only a key capacitor into an inductor, but also an added resistor, into a negative resistor. This gyrator-RC has its losses compensated by the negative resistor improving the active inductor Q factor. Changing the bias voltage and current allows to obtain a variable AI. A study of a cascade gyrator AI topology is done to understand the circuit behavior and key elements. For this purpose, an AI impedance model is introduced and discussed. An improved AI with the added resistor replaced by a voltage controlled mosfet resistor is proposed. This extra control voltage allows the variable AI quality factor fine tuning. Schematic and circuit extracted from layout simulations are presented, and compared with the measured results of two prototypes of the AIs (one with a fixed resistor and other with a voltage controlled resistor). A prototype of a high pass filter using the AI with fine Q control was fabricated. Non-linear simulations for different input signal levels were performed and compared with measurements. Also discussion on the non-linear models accuracy is performed.     

脊波导结构LiNbO3电光调制器研究与改进

采用有限元软件Ansys、运用有限元法,对脊波导结构铌酸锂电光调制器进行了优化设计。通过将传统结构与脊波导的比较分析,提出采用聚四氟乙烯部分取代缓冲层中的二氧化硅的结构,能更好的实现微波等效折射率的降低以达到与光波折射率的匹配,同时能保持更大的特性阻抗以实现阻抗匹配,从而更好的提高器件性能。     

20 Gbit/s operation of a high-efficiency InGaAsP/InGaAsP MQWelectroabsorption modulator with 1.2-V drive voltage

The authors have fabricated a ridge waveguide electroabsorption modulator based on the quantum-confined Stark effect in InGaAsP/InGaAsP multiple quantum wells. The drive voltage for 12-dB extinction ratio is 1.2 V, and the frequency response is flat within 2 dB from DC to 20 GHz. Operation at 20 Gb/s is reported. Extensive data concerning the parasitic phase modulation (chirping) are obtained as a function of applied bias acid operating wavelength     

40 Gbit/s differential distributed modulator driver realised in 80 GHz SiGe HBT process

A 40 Gbit/s, fully differential distributed SiGe HBT driver is presented. The IC is realised in a low-cost 80 GHz production process, and is intended to operate as a modulator driver in a 40 Gbit/s fibre-optic communication system. Resulting from the differential chip architecture, no off-chip low-frequency transmission line termination networks are required, which significantly alleviates the chip mounting process. Mounted in a coaxial test fixture, an eye opening of 2 1.25 V_pp at 40 Gbit/s operation is measured.     

High-speed (>40 GHz) integrated electroabsorption modulator based on identical epitaxial layer approach

An electroabsorption (EA) modulator is monolithically integrated with a semiconductor optical amplifier (SOA) using a very simple identical epitaxial layer (IEL) scheme. By adopting dry-etched high-mesa structure and thick SiO/sub 2/ beneath the bonding pad, the modulator capacitance is estimated to be less than 0.13 pF, and a 3-dBe bandwidth over 40 GHz has been demonstrated for the IEL-based integrated EA modulator. The SOA section helps reduce the coupling loss of the device, and the fiber-to-fiber loss is reduced from 18 to 3 dB at an injection current of 70 mA into the SOA section.