Phase tuning of injection-locked VCSELs

Phase tuning of injection-locked single-mode vertical-cavity surface-emitting laser diodes (VCSELs) is investigated experimentally with two slave VCSELs being locked by a master VCSEL. By slightly varying the laser current and thereby the frequency within the locking range, a maximum phase shift of more than 0.8 π is achieved. The method is applicable to large injection-locked VCSEL arrays     

MEMS magnetic field sensor based on silicon bridge structure

A MEMS piezoresistive magnetic field sensor based on a silicon bridge structure has been simulated and tested.The sensor consists of a silicon sensitivity diaphragm embedded with a piezoresistive Wheatstone bridge,and a ferromagnetic magnet adhered to the sensitivity diaphragm.When the sensor is subjected to an external magnetic field, the magnetic force bends the silicon sensitivity diaphragm,producing stress and resistors change of the Wheatstone bridge and the output voltage of the sensor.Good agreeme...     

基于硅桥结构的MEMS磁场传感器

提出了一种基于硅桥结构的MEMS磁场传感器结构。其结构由制作在硅桥敏感膜表面的惠斯通电桥和在膜中间沾上铁磁体制成。当传感器处于磁场中时,铁磁体在外磁场中磁化产生磁力,磁力会使硅敏感膜弯曲从而引起压阻改变进而使惠斯通电桥产生电压输出以达到测量磁场的目的。文章通过有限元软件仿真对铁磁体的尺寸进行了优化。实验结果和理论结果较接近。实验测得该传感器最大灵敏度为48mV/T,分辨率为160μT,该传感器可以用来进行强磁场的测量。实验结果结果表明:传感器的重复性和动态响应时间分别约为0.66%和150ms。     

Broadly wavelength-tunable external cavity lasers with extremely low power variation over tuning range

Tunable external-cavity lasers with low power variation over a broad tuning range are demonstrated using asymmetric multiple quantum-wells with a wide and flat gain. For a 2.8-/spl mu/m-wide ridge waveguide laser of cavity length 380 /spl mu/m, when used in a grating external cavity and with an antireflection coating on one facet of laser diode chip, the power variation of less than -1 dB is obtained over a range of 80 nm. This extremely low power variation is a direct result of the spectrally flat gain.     

Distributed MEMS analog phase shifter with enhanced tuning

The design, fabrication, and measurement of a tunable microwave phase shifter is described. The phase shifter combines two techniques: a distributed capacitance transmission line phase shifter, and a large tuning range radio frequency (RF) microelectromechanical system (MEMS) capacitor. The resulting device is a large bandwidth, continuously tunable, low-loss phase shifter, with state-of-the-art performance. Measurements indicate analog tuning of 170/spl deg/ phase shift per dB loss is possible at 40 GHz, with a 538/spl deg/ phase shift per centimeter. The structure is realized with high-Q MEMS varactors, capable of tuning C/sub max//C/sub min/= 3.4. To our knowledge, this presents the lowest loss analog millimeter wave phase shifter performance to date.     

Tunable MEMS LC resonator with large tuning range

A tunable resonator based on MEMS technology is reported. The resonator is a parallel LC type resonator, in which the capacitor is made up of two metal bridges and the inductor is made up of a shorted stub. The length of the shorted stub is changed by shunt DC contact switches and therefore inductance values of the resonator can be varied. As a result, the resonant frequency of the resonator can be shifted from 8 to 14 GHz with 75% tunable range. The whole size of the resonator is 6/spl times/0.9 mm/sup 2/.     

Long wavelength MEMS tunable VCSEL with InP-InAlGaAs bottom DBR

In this letter, we present the first demonstration of a long wavelength-tunable vertical-cavity surface-emitting laser (VCSEL) using an InP-InAlGaAs distributed Bragg reflector (DBR). The use of such a DBR improves the thermal resistance of the VCSEL while keeping the growth process simple. The devices show operation to temperatures greater than 75/spl deg/C, and single-mode devices emit powers as high as 0.9 mW at room temperature. The tuning range is as high as 17 nm.     

1.55-/spl mu/m optically pumped wafer-fused tunable VCSELs with 32-nm tuning range

We demonstrate widely tunable InAlGaAs-InP-AlGaAs-GaAs optically pumped vertical-cavity surface-emitting lasers operating in the 1.55-/spl mu/m waveband. The tuning range of 32 nm is achieved by applying a low tuning voltage of 4 V. Maximum single-mode output power of 2 mW with less than 1.5-dB power variation over the whole tuning range and side-mode suppression ratio in excess of 30 dB have been obtained.     

智能化数控调谐文氏电桥陷波器

介绍文氏电桥陷波器及其在失真度测量中的应用,提出一种智能化数控调谐的文氏电桥陷波电路.该电路利用AD536型真有效值检波器对文氏电桥陷波后的残余信号进行检测并进行模-数转换,由单片机控制文氏电桥的分档电容器和数控电位器,实现谐振频率的智能调谐.     

RF VCO tuning using MEMS piezoelectric actuated variable inductors

This paper presents a study on the use of microsystems technology in the design of radio frequency voltage-controlled oscillators. In particular, the application of a micro-electro-mechanical systems (MEMS) based variable inductor for frequency tuning purposes is presented. Although traditionally a MEMS variable inductor is considered as a means to extend the tuning range, in this work it is shown that with correct inductor design it is also possible to facilitate and improve the voltage-controlled oscillator design in terms of phase noise response and power consumption in comparison to a design based on standard capacitive tuning.     

一种用于RF MEMS移相器及开关可变电容的复合微桥膜结构

提出了一种基于微机械工艺的新型复合微桥膜结构 ,由低应力SiN/SiO2 (0 .5 μm/5 0nm )及Cr/Au(30nm/1μm)构成。相应的工艺流程较为简单。对影响其特性的因素进行了理论分析 ,并提出了 3种桥膜的平面结构 ;利用静电 /力耦合有限元法分析了各种结构的静电驱动特性以及各阶模态 ,结果得到了令人满意的驱动和机械性能 ;通过有限元高频仿真软件对桥膜结构与共面波导形成的可调电容结构进行了分析 ,结果表明其具有良好的射频 /微波性能。该桥膜结构适用于RFMEMS开关、移相器及开关式可调电容和滤波器等     

一种用于RF MEMS移相器及开关可变电容的复合微桥膜结构

提出了一种基于微机械工艺的新型复合微桥膜结构，由低应力SiN／SiO2(0.5μm／50nm)及Cr／Au(30nm／1μm)构成。相应的工艺流程较为简单。对影响其特性的因素进行了理论分析，并提出了3种桥膜的平面结构；利用静电／力耦合有限元法分析了各种结构的静电驱动特性以及各阶模态，结果得到了令人满意的驱动和机械性能；通过有限元高频仿真软件对桥膜结构与共面波导形成的可调电容结构进行了分析，结果表明其具有良好的射频／微波性能。该桥膜结构适用于RF MEMS开关、移相器及开关式可调电容和滤波器等。     

Single-polarization wavelength-tunable fiber laser with anonreciprocal cavity

Unidirectional, continuously tunable, and polarized oscillation in an erbium doped fiber ring laser is demonstrated without an isolator. Nonreciprocal oscillation is realized with one polarization splitter and two polarization controllers. Fine tuning is realized with fiber birefringence. The laser spectrum is continuously tunable from 1530 to 1560 nm with line widths less than 0.2 nm; the degree of polarization at the output is 92%     

微结构垂直腔面发射激光器的设计

具有高功率、单横模工作特性的垂直腔激光器(VCSEL)将会极大地扩展VCSEL激光器的应用领域,具备此性能的VCSEL激光器除了能增强它在短距离通信及光存储网络的应用之外,还将成为长距离光通信以及光传感系统里重要的器件.然而对于传统的VCSEL激光器,高功率和单横模工作特性很难同时获得,这是因为高功率输出通常将会增大输出孔径,大的输出孔径则会带来多横模振荡.文中通过在P-DBR层中引入纳米微结构,设计了一种能同时提供高功率、单横模输出的VCSEL激光器.这种新型的VCSEL激光器通过采用光子带隙的波导结构,使得设计的激光器在大输出孔径(直径达12 μm)时仍然保持单横模工作.     

优化结构的太赫兹Turbo编译码技术

主要阐述太赫兹(THz)通信系统中的信道编码部分,利用CPU多核进行并行计算,实现对Turbo码的编译码程序的加速。通过4个方面对Turbo码的编译码进行优化加速,包括预留内存空间、并行循环以及对编码结构和译码公式的优化,从而实现代码运行时间的缩短。经实验验证,经过对不同码长的数据进行编译码运算,发现在输入码长为10 000 bit时,并行计算时间可以缩短56.6%。     

A low-loss beam splitter with an optimized waveguide structure

Novel beam splitters with optimized waveguide structures are designed and fabricated using reactive ion etching. At 1.15 μm the excess loss of the beam splitter is measured to be 1.2 dB for TE and 1.8 dB for TM polarizations, respectively     

可调谐VCSEL的低应力MEMS悬臂结构设计

针对GaAs基和InP基材料的波长可调谐垂直腔面发射激光器（VCSEL）中微机电系统（MEMS）应力集中引起结构损坏的问题开展研究。设计了蝴蝶结状MEMS悬臂结构,在保证最大位移不变的情况下,降低了悬臂固定端所受的米塞斯应力,提高了器件的可靠性。采用COMSOL软件对蝴蝶结状悬臂结构的各项参数对力学特性的影响进行了优化与分析。结果表明:优化后的蝴蝶结状MEMS悬臂结构固定端的最大米塞斯应力相比于等截面状悬臂结构最大降低了64%,对于GaAs基材料的蝴蝶结状MEMS波长可调谐VCSEL自由光谱范围可达45 nm。     

A wavelength-tunable curved waveguide DFB laser with an integratedmodulator

A distributed-feedback (DFB) laser with a curved waveguide in the active region integrated with an electroabsorption modulator is studied experimentally and theoretically. The modulator controls the lasing wavelength of the DFB laser by acting as an optical phase shifter. Our model, which is based on the transfer matrix method, is used to simulate this multisection device with the curved waveguide, self-consistently including the effects of spatial hole burning (SHB). The model explains the features and wavelength-tuning behavior of the spectrum and shows good agreement with experimentally measured spectra. We also show theoretically that the curved waveguide suppresses the longitudinal photon density profile of the device compared with a straight waveguide case, which implies reduced SHB effects