A Directional Filter Diplexer Using Optical Techniques for Millimeter to Submillimeter Wavelengths

An optical diplexer for injection of a local oscillator into a mixer, useful in the submillimeter and short millimeter range, is described. It has very low insertion loss for both the signal and local oscillator (L.O.) and high rejection of L.O. noise. Measured performance of a unit tested at 337 GHz indicates ~.2 dB loss for both inputs and 20 dB noise rejection.     

High-order mode coupler for millimetre wavelengths

A new type of injection filter has been developed that can be used for local-oscillator injection in millimetre-wave mixers and other narrowband diplexing applications. The insertion loss for nonresonance frequencies is typically less than 0.25 dB. For the selected resonant modes, the coupler acts as a 3 dB power divider. Insertion losses of 1.5 dB or less can be reached at these frequencies.     

Low-loss fiber-chip coupling by InGaAsP/InP thick waveguides forguided-wave photonic integrated circuits

A generic waveguiding structure is reported with low coupling loss (⩽1 dB/facet) with lensed fibers and low propagation loss (⩽1 dB/cm). This structure is suitable for low loss guided-wave photonic integrated circuits including active elements such as switches, and passive interconnections such as mirrors, and allows low polarization dependent operation. Which is required for instance in wavelength demultiplexers. This structure based on a single epitaxy is of interest for low cost photonic switching fabrics     

低串扰载流子注入型光开关的设计

针对载流子注入马赫-曾德尔干涉型光开关,提出使用输出比可调的3dB耦合器,补偿相移臂上通过载流子注入实现π相位调制所产生的吸收损耗,从而降低光开关的串扰。使用传输矩阵方法计算分析了载流子注入所伴随的吸收损耗对光开关串扰的影响,同时计算了可调3dB耦合器对光开关串扰性能的改进。计算结果表明,可调3dB耦合器的引入可以有效补偿相移臂的吸收损耗,对改善光开关的串扰性能有着明显的作用。     

Group velocity dependence of propagation losses in single-line-defect photonic crystal waveguides on GaAs membranes

Group velocity, v/sub g/, dependence of propagation loss in single-line-defect photonic crystal waveguides on GaAs membranes, and minimum loss as low as 2.5 dB/mm, are presented. When v/sub g/ is reduced by a factor of 7, an additional loss is found to be only 5 dB/mm, thus proving a feasible usage of low v/sub g/.     

2×2多模干涉光开关的设计与制作

以多模干涉耦合器为主体,通过载流子注入效应所引起的折射率改变来调整二重像之间的相位差,当折射率下降所引起的相位改变达到π相位时完成开关功能。在AlGaAs/GaAs/AlGaAs外延材料上,利用两步湿法腐蚀工艺,实际制作了2×2光开关并进行了测试。测试结果表明,工作在1.55μm波段,当注入电流达到160mA时,完成了开关功能。     

一种低损耗高抑制的声表面波滤波器

该文采用周期调制及双通道设计的方法实现了一种低损耗高抑制声表面波滤波器的研制。该滤波器以64°Y X LiNbO3为基片材料,其中心频率约475 MHz,插入损耗小于2 dB,阻带抑制优于60 dB及1 dB相对带宽约5%。研制的滤波器具有低插损及高阻带抑制的特性,结果表明该设计方法具有很好的实用性。     

Splicing of Fibers by the Fusion Method

Single-mode fiber splicing requires quite a precise core alignment for the adjustment of core eccentricity and outer diameter discrepancies. Several core alignment methods have been developed. The typical four methods are as follows: 1) remote injection and remote detection systems (RIRDS), 2) remote injection and local detection systems (LDS), 3) local injection and detection systems (LIDS), 4) core direct monitoring systems. The so-called prefusion method has been developed to prevent bubble growth during the fusion process. This method is widely used for both single and multimode fiber arc fusion splicing machines. The average splicing losses of 0.11 dB and 0.10 dB are reported for single-mode fiber splicings with RIRDS by NTT in Japan, and by Bell-Northern Research in Canada, respectively. With the LIDS method, the average splicing loss of 0.13 dB in the field was reported by PTT in The Netherlands. With the core direct monitoring method, average splicing loss of 0.08 dB in the field was reported by NTT in Japan. This method is one of the simplest on the most useful core alignment for single-mode splicing machine. Splicing of multimode fiber does not require a precise core alignment; that is, the alignment by the cladding is sufficient for the low-loss splicing. Therefore, the mechanism for the alignment of the fibers is much simpler than that of single-mode fibers. The average splicing loss of 0.07 dB was reported by NTT in Japan in 1982. As mentioned above, this paper reviews the field experience with these different splicing methods.     

Silica-based integrated optic Mach-Zehnder multi/demultiplexerfamily with channel spacing of 0.01-250 nm

A Mach-Zehnder (MZ) interferometer design is presented for application to wavelength-division multiplexed/frequency division multiplexed (WDM/FDM) systems. A variety of integrated-optic devices with low loss and low crosstalk, using silica-based waveguides, are demonstrated. MZ interferometers operate as multi/demultiplexers or frequency-selection switches. The channel spacing is determined by the waveguide arm length difference, and a spacing range of 1 GHz to 36 THz, corresponding to a wavelength spacing of 0.008-250 nm, is achieved. The devices for the WDM region have low fiber-to-fiber loss of 0.5 dB, and the devices for the FDM region have higher losses of 2-5 dB. Crosstalk of less than -15 dB was obtained for all the devices. A 5-GHz-spaced 16-channel frequency selection switch and a 10-GHz-spaced eight-channel multi/demultiplexer were also fabricated with a total loss of 5 dB and total crosstalk of -10 dB or less     

Design and performance of an angled physical contact typemultifiber connector

An angled, physical contact type multifiber connector is developed on the basis of a structural design which enables direct fiber endface contact between multifiber arrays. The direct contact is achieved by utilizing the elastic nature of a ferrule material under compressive force. The fabricated connector provides a low insertion loss of 0.2 dB and a high return loss of 58.8 dB without index-matching. This connector is used in the successful development of push-on type and backpanel type 16-fiber connectors with a low insertion loss of 0.25 dB and a high return loss of 58.0 dB for future subscriber networks     

Active lossless monolithic one-by-four splitters/combiners usingoptical gates on InP

Active one-by-four splitters/combiners were fabricated on InP from the monolithic integration of waveguides and amplifiers. The device exhibited propagation loss below 1.5 dB·cm^-1, S-bend loss of 0.2 dB per bend, a 3-dB optical bandwidth of 23 nm, a mean optical crosstalk and extinction ratio of, respectively, 37 dB and 42 dB. On all paths, at least 0 dB insertion loss (fiber to-fiber gain up to 2.8 dB) as well as a low polarization sensitivity (below 1.0 dB) were demonstrated. This device can be used as the basic building block of bit-rate transparent switches for optical routing and broadcasting     

一种超低插损砷化镓射频开关

报道了利用离子注入技术研制出一种用于手机的超低插损砷化镓单片射频单刀双掷开关。该产品在82 0～ 95 0 MHz下 ,插入损耗≤ 0 .4 d B,回波损耗≥ 1 9.5 d B,反向三阶交调截距点≥ 67d Bm,隔离度≥ 1 5 .5 d B,控制电压为 (0 ,+4 .75 V)     

一种基于T型缺陷微带结构低通滤波器

提出了一种T型微带缺陷结构(DMS),并分析了其传输特性,设计并制作了一款基于T型DMS低通滤波器,仿真和实测结果表明,所设计的新型低通滤波器3 dB截止频率为2.9 GHz,通带插入损耗小于0.15 dB,回波损耗最大旁瓣优于15 dB。该滤波器设计方法简单,电磁泄漏小,体积小,并且易于与其他电路集成。     

应用于S波段的高线性低噪声放大器

采用E-mode 0.25um GaAs pHEMT工艺,2.0mm × 2.0mm 8-pin双侧引脚扁平封装,设计了一款应用于S波段的噪声系数低于0.5dB的低噪声放大器。通过采用共源共栅结构、有源偏置网络和多重反馈网络等技术改进了电路结构,该放大器具有低噪声,高增益,高线性等特点,是手持终端应用上理想的一款低噪声放大器。测试结果表明在2.3-2.7GHz内,增益大于18dB,输入回波损耗小于-10dB,输出回波损耗小于-16dB,输出三阶交调点大于36dB。     

A high-performance 40-85 GHz MMIC SPDT switch using FET-integrated transmission line structure

A compact ultra-broadband distributed SPDT switch has been developed using GaAs PHEMTs. An FET-integrated transmission line structure, where the source pad of the shunt FET has been integrated into the signal line while the drain has been grounded to a via-hole with minimum parasitic inductance, has been proposed to extend the operating bandwidth of the distributed switches. SPDT and SPST switches using this structure have been fabricated using a commercial GaAs PHEMT foundry. The SPDT switch showed low insertion loss (<2 dB) and good isolation (>30 dB) over an octave bandwidth from 40 to 85 GHz. At 77 GHz, the SPDT switch showed extremely low insertion loss of 1.4 dB and high isolation of 38 dB. The chip size was as small as 1.45/spl times/1.0 mm/sup 2/. To the best of our knowledge, this is among the best performance ever reported for an octave-band SPDT switch at this frequency range. SPST switch also showed the excellent performance with the insertion loss of 0.4 dB and isolation of 34 dB at 60 GHz.     

湿法腐蚀制备的SOI光波导

用化学湿法腐蚀的方法制作了SOI光波导,并且用三维波束传播方法分析和设计了单模波导和1×2 3dB多模干涉分束器,修正了有效折射率和导模传输方法的误差.制作的器件具有低传输损耗(-1.37dB/cm)、低附加损耗(-2.2dB)、良好的均衡性(0.3dB)等优良性能.     

High-performance GaAs switch IC's fabricated using MESFET's withtwo kinds of pinch-off voltages and a symmetrical pattern configuration

GaAs MESFET switch IC's operating at low control voltages of 0/-3 V and +3/0 V have been developed for use in Personal Handy Phones using the 1.9 GHz band. The switch IC's have excellent RF characteristics, and have no need for external circuit installation. The unique points of these IC's are the use of GaAs MESFET's with two kinds of pinch-off voltages and a symmetrical source and drain pattern configuration with respect to the gate. The 0/-3 V IC had low insertion loss of 0.55 dB and 0.65 dB, and high isolation of 31 dB and 24 dB at receiving and transmitting operations, respectively. The +3/0 V IC also had excellent characteristics such as insertion loss of 0.73 dB and 0.95 dB, and isolation of 27 dB and 23 dB, respectively. Both IC's had an output power at 1 dB gain compression point of 25.4 dBm and 3rd order intercept point of more than 46 dBm     

Polarization and wavelength insensitive MQW electroabsorption optical gates for WDM switching systems

We propose using MQW electroabsorption (EA) modulators as optical gates in wavelength-division-multiplexing (WDM) switching systems. A fabricated MQW-EA gate with integrated waveguides showed a high extinction ratio (>30 dB), a low polarization-dependent loss (0.3 dB), and a low wavelength-dependent loss (1.1 dB) within the gain band (1545-1560 nm) of erbium doped fiber amplifiers (EDFAs). Ultra-high-speed (<40 ps) switching of a WDM signal was demonstrated.     

Low conversion-loss fourth subharmonic mixers incorporating CMRC for millimeter-wave applications

Low conversion-loss millimeter-wave fourth subharmonic (SH) mixer designs are proposed in this paper. A millimeter-wave (35 GHz) fourth SH mixer with four open/shorted stubs is designed and measured. The conversion loss is less than 15 dB within a 2.4-GHz bandwidth. The minimum loss is 11.5 dB at the center frequency. By replacing two of the shunt stubs with a dual-frequency in-line stub consisting of newly developed compact microstrip resonating cells (CMRCs), the performance of the SH mixer is improved significantly. At 35 GHz, the conversion loss of this new fourth SH mixer is as low as 6.1 dB with a 3-dB bandwidth of 6 GHz. The conversion loss in the whole Ka-band (26.5-40 GHz) is less than 16 dB. The proposed fourth SH mixer incorporating with CMRCs provides a low-cost high-performance solution for RF subsystem design.     

Wideband planar lightwave circuit type variable optical attenuator using phase-generating coupler

A novel wideband planar lightwave circuit type variable optical attenuator (VOA) that incorporates a phase-generating coupler is proposed. The proposed VOA was fabricated on a 1.5%-/spl Delta/ silica-based waveguide, and obtained a low insertion loss of less than 1.2 dB and a low wavelength dependent loss of less than 0.8 dB at attenuation levels of 0 to 25 dB over the C- and L-band wavelength range.