基于绝缘层上硅平坦化阵列波导光栅的单纤三向器

设计了基于绝缘层上硅(SOI)平坦化阵列波导光栅单纤三向器.三向器三个波长(1310,1490和1550nm)工作在阵列波导光栅的三个不同的衍射级数,并在阵列波导光栅的输入波导末端引入多模干涉器(MMI),实现了平坦响应的三波长波分复用.模拟结果表明基于这一设计的三向器3dB带宽为6nm,串扰小于-40dB,插损为5dB.制备的三向器经测试输出光场清晰,实现了三向器的功能.     

Wide Temperature Range Operation of a 1.55-$mu$m 40-Gb/s Electroabsorption Modulator Integrated DFB Laser for Very Short-Reach Applications

We present the uncooled operation of a 1.55- mum 40-Gb/s InGaAlAs electroabsorption modulator (EAM) integrated distributed-feedback (DFB) laser within a temperature range of 95degC (-15degC to 80degC ). To the best of our knowledge, this is the largest temperature range reported so far for such a 40-Gb/s EAM integrated DFB laser. We designed the EAM to operate at high speed by reducing the electrical parasitics, and we achieved a 3-dB frequency bandwidth of over 39 GHz for an EAM length of less than 150 mum. We demonstrated a 2-km single-mode fiber (SMF) transmission at 40-Gb/s over a wide temperature range of -15degC to 80degC by adjusting only the bias voltage to the EAM while keeping the modulation voltage swing constant at 2.0 V when the temperature changed. We achieved a dynamic extinction ratio of over 8.2 dB and a 2-km SMF transmission with a power penalty of less than 2 dB over a wide temperature range.     

An image-rejection down-converter for low-IF receivers

Implemented in 4.1 mm² in 130-nm CMOS, a dual-conversion image-rejection down-converter applied to the wireless code-division multiple-access (WCDMA) standard draws 13 mA from a single 1.8-V power supply. Using an IF of 2.5 MHz, the WCDMA image-rejection band is widened from 0.58-4.42 MHz to 0.48-5.2 MHz-a bandwidth ratio of 10.8-to accommodate process, voltage, and temperature variations in high-volume production. Ten samples are measured and fully characterized: average image-rejection ratio (IRR) is 46.6 dBc, gain is 12 dB, and noise figure is 10.8 dB. Typical IRR is 44.8, 46.5, and 47.5 dBc at -20degC, 25degC, and 80degC, respectively     

Dark-Current Suppression in Metal–Germanium–Metal Photodetectors Through Dopant-Segregation in NiGe—Schottky Barrier

We demonstrate, for the first time, the application of dopant-segregation (DS) technique in metal-germanium- metal photodetectors for dark-current suppression and high-speed performance. Low defect density and surface smooth epi-Ge (~300 nm) layer was selectively grown on patterned Si substrate using two-step epi-growth at 400degC/600degC combined with a thin (~10 nm) low-temperature Si/Si_0.8 Ge_0.2 buffer layer. NiGe with DS effectively modulates the Schottky barrier height and suppresses dark current to ~10 ^-7 A at -1 V bias (width/spacing: 30/2.5 mum). Under normal incidence illumination at 1.55 mum, the devices show photoresponsivity of 0.12 A/W. The 3 dB bandwidth under - 1 V bias is up to 6 GHz.     

Small-size silicon-oxynitride AWG demultiplexer operating around725 nm

We present experimental results of very compact, high Δn, five-channel arrayed waveguide gratings (AWGs) with 5 nm-channel-spacing fabricated in the silicon-oxynitride material system. The on-chip insertion loss is about 5 dB and the crosstalk is -30 dB around 725 nm wavelength. The uniformity of the waveguide layers is better than ±1%,     

A Sub-1-V, 10 ppm/ °C, Nanopower Voltage Reference Generator

An extreme low power voltage reference generator operating with a supply voltage ranging from 0.9 to 4 V has been implemented in AMS 0.35-mum CMOS process. The maximum supply current measured at the maximum supply voltage and at 80degC is 70 nA. A temperature coefficient of 10 ppm/degC is achieved as the combined effect of 1) a perfect suppression of the temperature dependence of mobility; 2) the compensation of the channel length modulation effect on the temperature coefficient; and 3) the absence of the body effect. The power supply rejection ratio without any filtering capacitor at 100 Hz and 10 MHz is lower than -53 and -42 dB, respectively. The occupied chip area is 0.045 mm².     

Performance analysis of a dispersion compensator usingarrayed-waveguide gratings

We have developed a dispersion compensator that uses arrayed-waveguide gratings (AWGs) and a spatial filter. The compensator using AWGs with 380 waveguides in each array and the diffraction order of 53, can compensate a total second-order dispersion of 260 ps/nm with an eye-closure penalty of 1 dB for a 40-Gb/s nonreturn-to-zero (NRZ) signal. It is shown that the required spatial resolution of the spatial phase filter for compensation is 2.55 μm for silica AWGs of usual design. The acceptable fluctuation in the refractive index of the waveguides in the AWGs is as large as 5×10^-5     

10-GHz-spaced 1010-channel tandem AWG filter consisting of oneprimary and ten secondary AWGs

A very large channel-count arrayed waveguide grating (AWG) filter with more than 1000 channels is described. It was achieved by cascading a 1-THz-spaced flat-top 1×10 AWG as a primary filter and ten 10-GHz-spaced 1×160 AWGs as secondary filters in a tandem configuration. We achieved good adjacent and accumulated channel crosstalk values ranging from -32 to -25 dB and from -24 and -18 dB, respectively     

High-Reliable and High-Speed 1.3 μm Complex-Coupled Distributed Feedback Buried-Heterostructure Laser Diodes With Fe-Doped InGaAsP/InP Hybrid Grating Layers Grown by MOCVD

In this paper, we report the fabrication of high-reliability and high-speed 1.3 mum complex-coupled distributed feedback (CC-DFB) buried heterostructure (BH) laser diodes (LDs) with Fe-doped InGaAsP/InP hybrid grating layers. High optical coupling coefficient and eminent current confining ability are accomplished by combining the Fe-doped InGaAsP/InP current-blocking-grating (CBG) layers to provide both the distributed-feedback index-and gain-coupling coefficients. Besides, the narrow-stripe BH LDs are implemented by burying the active region with a Fe-doped InP current-blocking layer during the epitaxial regrowth. The fabricated CBG CC-DFB BH LDs at 20degC shows a low threshold current of 5.3 mA, a maximum light output power of 36 mW at 100 mA, a high slope efficiency of 0.41 mW/mA, and a side-mode suppression ratio (SMSR) of 42 dB at twice the threshold. In addition, these LDs exhibit a maximum operation temperature of 125degC, an extremely low threshold current of 15.8 mA at 90degC, a small variation in slope efficient of only -1 dB in the temperature range from 20degC to 80degC, and a characteristic temperature of 77 K and 56 K between 20 degC and 60degC, and 70degC and 120degC, respectively. Furthermore, these 1.3 mum CBG CC-DFB BH LDs exhibit a high-speed characteristic up to 11.8 GHz at room temperature and an estimated median lifetime of more than 1.1 times 10⁵ h or 12.5 years at 5 mW and 85degC.     

Temperature insensitive 1.3 /spl mu/InGaAs=GaAs quantum dot distributed feedback lasers for 10 Gbit=s transmission over 21km

Long wavelength monomode InGaAs/GaAs quantum dot (QD) distributed feedback (DFB) lasers with emission wavelength around 1325 nm are presented. Threshold currents below 19 mA for operating temperatures up to 70degC and output powers of 10 mW at 25degC (6 mW at 70degC) are observed. Error-free 10 Gbit/s transmission over 21 km fibre with an extinction ratio of 8.5 dB at room temperature (5.1 dB at 70degC) is demonstrated. The low threshold, low temperature sensitivity and high modulation speed were realised using complex coupled DFB lasers with ten stacks of self-organised MBE-grown QD layers and p-type modulation doping     

基于绝缘层上硅平坦化阵列波导光栅的单纤三向器

设计了基于绝缘层上硅(SOI)平坦化阵列波导光栅单纤三向器.三向器三个波长(1310,1490和1550nm)工作在阵列波导光栅的三个不同的衍射级数,并在阵列波导光栅的输入波导末端引入多模干涉器(MMI),实现了平坦响应的三波长波分复用.模拟结果表明基于这一设计的三向器3dB带宽为6nm,串扰小于-40dB,插损为5dB.制备的三向器经测试输出光场清晰,实现了三向器的功能.     

The first hot pluggable 2.5 Gb/s DWDM transceiver in an SFP form factor

For the first time, a hot pluggable 2.5 Gb/s DWDM transceiver with 100 GHz spacing in an SFP form factor has been presented. We demonstrate transmit wavelength drift of plusmn9 pm and optical output power stability of 0.2 dB over an operating case temperature range of -5degC to 70 degC. The minimum receive sensitivity was -33.2 dBm for back-to-back, -32.6 dBm after transmission over 80 km of standard SMF, and -28 dBm for an OSNR level of 16 dB at a BER of 1 times 10^-10      

A Cool, Sub-0.2 dB Noise Figure GaN HEMT Power Amplifier With 2-Watt Output Power

This paper reports on a S-, C-band low-noise power amplifier (LNPA) which achieves a sub-0.2 dB noise figure (NF) over a multi-octave band and a saturated output power (Psat) of 2 W at a cool temperature of -30degC . The GaN MMIC is based on a 0.2 mum AlGaN/GaN-SiC HEMT technology with an f_T ~ 75 GHz. At a cool temperature of -30degC and a power bias of 15 V-400 mA, the MMIC achieves 0.25-0.45 dB average NF over a 2-8 GHz band and a linear P_1dB of 32.8 dBm ( ~ 2 W) with 25% power-added efficiency (PAE). At a medium bias of 12 V-200 mA, the amplifier achieves 0.1-0.2 dB average NF across the same band and a P_1dB of 32.2 dBm (1.66 W) with 35% PAE. The corresponding saturated output power is greater than 2 W. At a low noise bias of 5 V-200 mA, a remarkable 0.05-0.15 dB average NF is achieved with a P_1dB > 24 dBm and PAE ~ 33%. These results are believed to be the lowest NF ever reported for a multi-octave fully matched MMIC amplifier capable of > 2 W of output power.     

A MEMS VOA Using Electrothermal Actuators

A comprehensive study of electrothermally driven microelectromechanical system (MEMS) variable optical attenuator (VOA) devices using an H-shaped structure is presented in this paper. Based on its unique structural design, a retroreflection-type VOA of smaller footprint is realized. The repeatability and stability of the static and transient characteristics of attenuation behavior at various ambient temperatures are characterized. The fluctuation of attenuation curves under the same driving voltage at the same ambient temperatures is less than plusmn0.1 dB. Again, comparing the attenuation curves measured at 25 degC to 75 degC and at 25 degC to 12.5 degC, the deviation of attenuation under the same driving voltage is within the 0.6-dB range. Within the 40-dB attenuation range, the measured switching time from nonattenuation state to a particular attenuation state or between two attenuation states is less than 10 ms. This electrothermally actuated MEMS VOA also demonstrates the state-of-the-art dynamic attenuation stability that complies with the Telecordia GR1221 regulations, where the dynamic fluctuation of attenuation at 20 dB is less than plusmn0.36 dB under a vibration testing condition of 20 G periodical shocks with frequency from 20 Hz to 2 kHz     

Lossless electroabsorption modulator monolithically integrated with a semiconductor optical amplifier and a passive waveguide

We have developed a monolithic integrated device consisting of an electroabsorption modulator and a semiconductor optical amplifier (SOA) connected by a deep-ridge passive waveguide by means of butt-joint selective area growth. Lossless operation with a high extinction ratio of 32 dB and clear eye opening at 10 Gb/s are successfully achieved. We confirm that the optical injection should be from the SOA side of the device to obtain a wide error-free range of incident optical power from -20 to +10 dBm. Our device could lead to richly functional photonic integrated circuits comprising arrayed waveguide gratings (AWGs) for advanced wavelength-division-multiplexing networks, since the passive waveguide has the same structure as AWGs.     

Low-cost WDM-PON with colorless bidirectional transceivers

This paper presents a low-cost bidirectional (BiDi) wavelength-division-multiplexed passive optical network (WDM-PON) employing colorless uncooled BiDi transceivers (TRxs) and superluminescent diode (SLD)-based broadband light sources (BLSs). The C band is allocated for upstream and the E+ band for downstream in consideration of BiDi packaging, SLD development, and wavelength alignment of dual-window arrayed waveguide gratings (AWGs). The BiDi TRx integrates an uncooled Fabry-Perot laser diode (FP-LD), a p-i-n photodiode (PD), and a 45/spl deg/-angled thin-film filter in a small-form-factor (SFF) package. The SLD-based BLSs provide 13-dBm amplified spontaneous emissions (ASEs) with spectral ripples of < 3 dB and polarization dependencies of <1 dB. Colorless operations over 32 100-GHz-spaced channels are demonstrated from -20 to 80/spl deg/C in 155-Mb/s BiDi transmissions over 25 km.     

Compact wide-band polymer wavelength-division multiplexers

Wide-band wavelength-division multiplexers (WDMs) have been developed for applications in short-haul and satellite communications. Device designs based on Mach-Zehnder interferometers (MZIs) and arrayed waveguide gratings (AWGs) have been fabricated using AlliedSignal Inc. low-loss acrylate polymer materials. Low channel-counts and channel separations of 5-30 nm result in compact devices with relaxed processing tolerances, thus minimizing the cost and increasing the yields of the devices. Operating at around 1550 nm, the multiplexers offer crosstalk of 20-25 dB, on-chip loss of <10 dB, thermal stability within several degrees and low polarization sensitivity     

Multilayer Organic Multichip Module Implementing Hybrid Microelectromechanical Systems

We present the design and development of an organic package that is compatible with fully released RF microelectromechanical systems (MEMS). The multilayer organic package consists of a liquid-crystal polymer film to provide near hermetic cavities for MEMS. The stack is further built up using organic thin-film polyimide. To demonstrate the organic package, we have designed and implemented a 2-bit true-time delay X-band phase shifter using commercially available microelectromechanical switches. The packaged phase shifter has a measured insertion loss of 2.45 plusmn 0.12 dB/bit at 10 GHz. The worst case phase variation of the phase shifter at 10 GHz is measured to less than 5deg. We have also conducted temperature cycling (-65degC to 150degC) and 85/85 to qualify the packaging structures.     

Silica-based 71-channel arrayed waveguide grating

With the rapid increase of global information capaci-ty,all optical wavelength division multiplexing(WDM)networks are very attractive because they are capable ofprocessing broadband optical signals without convertingthem to electronic signals.Large channe…     

Uncooled 25 Gbit/s direct modulation of semi-insulating buried-heterostructure 1.3 μm AlGaInAs quantum-well DFB lasers

Uncooled 25 Gbit/s direct modulation of 1.3 mum DFB lasers is demonstrated. The 150 mum-long semi-insulating buried-heterostructure AIGalnAs quantum-well DFB lasers show clear eye-openings with dynamic extinction ratio of 5 dB up to 70degC. 13 km singlemode-fibre transmission experiments using the devices show low power penalty within 1.3 dB between 25 and 70degC. These characteristics are the first achievement by 1.3 mum directly modulated lasers.