17×17 硅基聚合物信道箱形光谱阵列波导光栅的制备

Arrayed waveguide grating (AWG) is a key device in wavelength-division multiplexing (WDM) system, and the flat spectral response of the AWG device is required. In this paper, the RIE process has been improved. By using the steam- redissolution technique, the insertion loss and the crosstalk have been reduced. Experimental results show that the central wavelength is 1550.86nm, and 3-dB bandwidth is about 0.478 nm, insertion loss is 10.5 dB, crosstalk is about –22 dB. The insertion loss of an AWG device is reduced by about 3 dB for the central channel and 4.5 dB for the edge channels, and the crosstalk is reduced by 2.5 dB after the steam- redissolution.     

Ultra compact triplexing filters based on SOI nanowire AWGs

An ultra compact triplexing filter was designed based on a silicon on insulator(SOI) nanowire arrayed waveguide grating(AWG) for fiber-to-the-home FTTH.The simulation results revealed that the design performed well in the sense of having a good triplexing function.The designed SOI nanowire AWGs were fabricated using ultraviolet lithography and induced coupler plasma etching.The experimental results showed that the crosstalk was less than -15 dB,and the 3 dB-bandwidth was 11.04 nm.The peak wavelength output from ports a,c,and b were 1455,1510 and 1300 nm,respectively,which deviated from our original expectations.The deviation of the wavelength is mainly caused by 45 nm width deviation of the arrayed waveguides during the course of the fabrication process and partly caused by material dispersion.     

Study of WDM polymer planar curved waveguide couplers

A wavelength division multiplexer based on curved polymer planar waveguide is proposed. According to the coupled modetheory and the waveguide structure, the performance of the curved waveguide coupler (CWC) is analyzed. The results showthat CWC can accommodate wider multiplexing bandwidth than parallel straight waveguide coupler (SWC) due to thecompensation effect of the effective coupling length. The two variables, curvature radius and minimum spacing, increasethe design flexibility of the waveguide device. A 4-channel wavelength division multiplexing (WDM) system based onCWC is designed. The deviation of the center wavelength, due to the errors of curvature radius and minimum spacingduring fabrication process, is investigated. The smaller the curvature radius and the minimum spacing are, the larger thecentral wavelength deviation caused by the error of the curvature radius and the minimum spacing is, which provides someuseful theoretical basis for the design and the fabrication of polymer waveguide devices.     

Fabrication of 17×17 polymer/Si arrayed waveguide grating with flat spectral response using steam-redissolution technique

Arrayed waveguide grating(AWG) is a key device in the wavelength-division multiplexing(WDM) system, and the flat spectral response of the AWG device is required.In this paper,the RIE process has been improved.By using the steam-redissolution technique,the insertion loss and the crosstalk have been reduced.Experimental results show that the central wavelength is 1550.86 nm,the channel spectral response flatness is about 1.5 dB,3-dB bandwidth is about 0.478 nm,insertion loss is 10.5 dB,and crosstalk is abo...     

A 45-channel 100 GHz AWG based on Si nanowire waveguides

A 45-channel 100 GHz arrayed waveguide grating (AWG) based on Si nanowire waveguides is designed, simulated and fabricated. Transfer function method is used in the spectrum simulation. The simulated results show that the central wavelength and channel spacing are 1 562.1 nm and 0.8 nm, respectively, which are in accord with the designed values, and the crosstalk is about ?23 dB. The device is fabricated on silicon-on-insulator (SOI) substrate by deep ultraviolet lithography (DUV) and inductively coupled plasma (ICP) etching technologies. The 45-channel 100 GHz AWG exhibits insertion loss of 6.5 dB and crosstalk of ?8 dB. This work has been supported by the National High Technology Research and Development Program of China (No.2015AA016902), and the National Natural Science Foundation of China (Nos.61435013 and 61405188). E-mail:zhangjiashun@semi.ac.cn      

Photovoltaic Response Characteristics of GaAs Photoconductive Switches Under High Gain Mode

Given is the experiment results in which the laser pulses of 1 046 nm and 532 nm are used to trigger the semi-insulation GaAs photoconductive semiconductor switch（PCSS） with an electrode distance of 4 mm. And made is an analysis of the switch＇s photovoltaic response characteristics under the high gain mode when the biased field is bigger than the Geng effect field. Also a theory is presented that the main reason for the photovoltaic pulse response delay is the transmission of charge domain, caused by the presence of EL2 energy level in the chip material. Finally, the transmission time of charge domain is calculated and a result that inosculates with the experiment is attained.     

Two different LNA optimizing techniques

Two different LNA design techniques,namely the classical two-port technique and the Shaeffer technique, have been introduced,compared and implemented for practical design.Their merits and drawbacks are also discussed.This paper mainly focuses on the former technique,which is seldom introduced in traditional papers. Since a parasitic capacitor of the transistor is included in the computation of the former technique,the errors caused by the ignorance of the capacitor have been minimized,which is superior to traditional techniques.Using the former technique,a fully integrated LNA is realized with only 1.4 dB while drawing 1.3 mA DC at 2.4 GHz for simulation results.Another version of the LNA is designed using the latter technique,which has been fabricated.     

Design of an ultra-compact 3 dB MMI coupler

The design of an ultra-compact SOI-based 1×2 3 dB multimode interference（MMI） coupler is proposed.The symmetric multimode interference structure and deeply-etched parabolically tapered multimode waveguide are used in the device.The length of the device is reduced by about 87% compared with general multimode interference straight couplers.Based on effective index method（EIM） and two dimensional beam propagation method（2D-BPM）,the structure parameters are optimized and the fabrication tolerances are analyzed.The results indicate that the performance of the coupler is deeply affected by the coupler＇s width,etching depth and photolithography alignment error in perpendicular direction.     

Optimization of a polymer four-port microring optical router with three channel wavelengths

Optimization and simulation are performed for a polymer four-port microring optical router with three channel wavelengths, which contains four-group basic routing elements with two different ring radii. In terms of microring resonance theory, coupled mode theory and transfer matrix method, expressions of output power of basic routing element and optical router are derived. In order to realize single-mode propagation, low optical transmission loss and phase match between microring waveguide and channel waveguide, the device parameters are optimized. With the selected three channel wavelengths of 1550 nm, 1552 nm and 1554 nm, characteristics are calculated and analyzed, including output spectrum, insertion loss and crosstalk. Simulation results indicate that the device has 12 possible I/O routing paths, the insertion losses of three channel wavelengths along their routing paths are within the range of 0.02-0.61 dB, the maximum crosstalk between the on-port along each routing path and other off-ports is less than -39 dB, and the device footprint size is -0.13 mm^2. Based on the proposed structure, through proper selection on ring radius, the routing structure can also be used for other channel wavelengths. Therefore, the designed structure shows wide applications in integrated optical networks-on-chip （NoC）.     

Digital background calibration of capacitor mismatches and harmonic distortion in pipelined ADC

A correlation-based digital background calibration algorithm for pipelined Analog-to- Digital Converters (ADCs) is presented in this paper. The merit of the calibration algorithm is that the main errors information, which include the capacitor mismatches and residue amplifier distortion, are extracted integrally. A modified 1st pipelined stage is adopted to solve the signal overflow caused by the Pseudo-random Noise (PN) sequences. Behavioral simulation results verify the effectiveness of the algorithm. It improves the Signal-to-Noise-plus-Distortion Ratio (SNDR) and Spurious-Free-Dynamic-Range (SFDR) of the pipelined ADC from 41.8 dB to 78.3 dB and 55.6 dB to 98.6 dB, respectively, which is comparable to the prior arts.     

Author Index Volume 17

Wireless Personal Communications -     

Contents of Volume 17

Wireless Personal Communications -     

A 17-ns 4-Mb CMOS DRAM

A 17-ns nonaddress-multiplexed 4-Mb dynamic RAM (DRAM) fabricated with a pure CMOS process is described. The speed limitations of the conventional DRAM sensing technique are discussed, and the advantages of using the direct bit-line sensing technique are explained. A direct bit-line sensing technique with a two-stage amplifier is described. One readout amplifier is composed of a two-stage current-mirror amplifier and a selected readout amplifier is activated by a column decoder output before the selected word line rises. The amplifier then detects a small bit-line signal appearing on a bit-line pair immediately after the word-line rise. This two-stage amplification scheme is essential to improving access time, especially in the case of a CMOS process. The high sensitivity of the readout amplifier is discussed, and the electrical features and characteristics of the fabricated DRAM are reported