卤-钨灯泵浦的Nd:YAG连续激光器的寿命问题(Ⅰ)

本工作的目的之一是研制一台长寿命的卤一钨灯泵浦的Nd:YAG连续激光器,为实际应用创造必要的条件。文章介绍了第一阶段的试验情况,用黄色玻璃管加蒸溜去离子水滤光器代替了重铬酸钾滤光液,给出了两者在紫外区的光谱特性曲线及泵浦结果。比较后认为,此种黄色玻璃管可用作Nd:YAG泵浦腔的滤光器。在长时间连续泵浦过程中,不会出现像重铬酸钾滤光液那样的沉积物,延长了激光器的寿命。提供了国产1300瓦市售碘-钨灯泵浦的Nd:YAG激光器的累积运转寿命试验数据,此时,该激光器的累积运转寿命为15小时。     

激光二极管泵浦的Rb原子共振滤光器

原子共振滤光器(ARF)是一种新型的量子、电子器件,是国际上近年来新发展的一种光学滤光器件。它具有超窄带宽(约0.01?)、大接收角(±90°)等特点,其滤光信噪比比干涉滤光片高二、三个数量级,因而在通信、遥控等领域有重要应用。本文报告国内首次观测到的激光二极管(LD)泵浦的Rb原子共振滤光器的窄带滤光效应。 LD的780nm光将Rb原子从基态(5S_(3/2))泵浦到5P_(3/2)态,当有572nm信号光输入时,5P_(3/2)态Rb原子受激跃迁至7d态,7d态原子经6p、7p、8p态返回基态,分别     

钠黄光场电离原子滤光器方案的实验研究

本文报道了在钠原子上利用电场电离探测的一种原子滤光方案的实验结果。采用与本实验相同的方案和不同的碱金属原子,可以制成具有各种不同波长的场电离原子滤光器。     

反常色散原子滤光器斜入射机理及特性研究

本文首次对反常色散原子滤光器在斜入射(0~π/2)条件下的透过率、带宽和频移等特性进行了理论研究;本文还进行了斜入射的滤光器透射谱实验研究,与理论分析符合较好;这些为原子滤光器在卫星及空间光通信领域的宽视场角接收方案奠定了基础,该方案有利于空间瞄准及捕捉.     

无线光通信系统中佛克脱原子滤光器技术研究

首次将新型佛克脱原子滤光器（VADOF）用于无线光通信,该系统既可用于地面光通信,也可用于卫星光通信系统。系统发射端采用光反馈、电扫描方案,将半导体激光频率锁定在VADOF透射峰,接收端采用原子滤光器窄带滤光技术。实验表明,发射频率与接收原子滤光器匹配很好。     

卫星光通信链路新型宽视场角捕捉方案探讨

本文提出了一种在卫星光通信链路建立中利用原子滤光器多峰特性的新型捕捉系统方案,可以将原子滤光器等效带宽减少到０００７ｎｍ,在实现宽视场角接收情况下进一步减少捕捉时间,并能满足卫星运动中的多普勒频移要求．此外本文讨论了该系统中原子滤光器等效带宽与接收视场角、信标发散角、最大捕捉时间等捕捉系统主要性能参数之间的关系．     

钾原子滤光器在太阳高分辨率观测中的应用

太阳高分辨率速度场观测系统可用于探测日震的活动信息,对太阳内部结构的研究具有重要意义。探讨了双峰钾原子滤光器在太阳光球层速度场观测中的应用方法,即利用法拉第反常色散原子滤光器(FADOF)的高光谱分辨率和光谱稳定性等优点,采用双峰钾原子滤光器分辨来自太阳光球层钾线(769.898nm)光谱的多普勒频移,并提出用F-P标准具对透过原子滤光器的双峰信号进行光学选支,从而获得太阳光球层多普勒速度场图像。研制出双透射峰钾原子滤光器原理样机,经测试其谱型与理论谱型符合良好,满足太阳速度场高分辨率观测的需要。将此技术方案扩展到太阳的其他谱线,可实现对太阳大气多层次速度场的同时观测。     

卫星光通信链路新型宽视场角埔捉方案探讨

本文提出了一种在卫星光通信链路建立中利用原子滤光器多峰特性的新型捕捉系统针原子光器等效带宽减少到０．００７ｎｍ,在实现宽视场角接收情况下进一 捕捉时间,并能满足卫星运动中的多普勒频移要求,此外本文讨论了该系统中原子滤光器等效带宽与接收视场角、信标发散角、最大捕捉时间等捕捉系统主要性能参数之间的关系。     

超窄带滤光技术研究进展

对自适应光学中激光导星的基本原理及系统中所需的超窄带滤光技术作了简单的介绍.重点介绍了一些有望应用于激光导星系统上的滤光技术,如:原子共振光学滤光器、双折射滤光器、法拉第反常色散滤光器、法布里-珀罗滤光器等.针对以上滤光技术各自的特点,阐明了它们的基本原理,给出了部分主要参数,并且对各滤光技术的发展现状和不足作了简要阐述.     

采用原子滤光器可调谐特性的新型卫星光通信捕捉方案研究

本文提出了在卫星光通信链路中利用原子滤光器可调谐特性的新型捕捉系统方案,可以将原子滤光器带宽的典型值减小到0.01nm,该方案可以适应低轨道卫星(LEO)到同步轨道卫星(GEO)任意可见时刻建立链路的需要,本文并对该方案进行了初步实验研究.     

A Tunable Lyot Birefringent Filter With Variable Channel Spacing and Wavelength Using Nonlinear Polarization Rotation in an SOA

We experimentally demonstrate a tunable fiber-optical Lyot birefringent comb filter with independent tuning of the channel spacing and wavelength. The filter configuration is based on sandwiching a fiber-optic programmable differential group delay line (DGDL) and a semiconductor optical amplifier (SOA) between two polarizers. The channel spacing of the filter can be tuned by adjusting the programmable DGDL. Using the nonlinear polarization rotation effect in the SOA, the phase shift between the transverse electric and the transverse magnetic components of the input probe beam can be adjusted by varying the power of the pump light, and hence fast and continuously wavelength tuning of the filter can also be achieved. The wavelength tuning range is up to 50% of the channel spacing when the pump power is increased from ${-}$10 to 17 dBm.      

Multipassband electronically tunable magnetostatic wave filter

A new design for a multipassband microwave filter based on magnetostatic waves propagating in a multilayer planar ferrite structure is described. The experimentally realised filter had two passbands of 10 MHz bandwidth and 5-6 dB insertion loss separated by 400 MHz, and was tuned with an external magnetic field over the 2.5-4 GHz range.<>     

Low-noise extended L-band phosphorus co-doped silicate EDFA consisting of novel two-stage gain-flattened gain blocks

A novel low-noise extended L-band silicate erbium-doped fibre amplifier (EDFA) is proposed, consisting of two novel gain-flattened gain blocks for wavelength-division multiplexing (WDM) signals from 1562.2 to 1619.6 nm. Each gain block consists of three isolated phosphorus/ alumina co-doped silicate EDFs, an intermediate embedded gain flattening filter (GFF), a short wavelength pump laser diode, and a pump bypass and/or a recycle path. The proposed EDFA, which uses only three pump laser diodes, has achieved noise figures as much as 6.1 dB lower than those realised by an earlier EDFA, when its intermediate optical attenuator has large signal losses and the input signal power is low.     

Research on transmission spectra of one-dimensional magneto-photonic crystals

A magneto-photonic crystal （MPC） is defined as a periodic light-guided structure involving magnetic materials or a photo- nic crystal with some magnetic-material defects. The transfer matrices of guided optical waves （GOWs） propagating re- spectively in magneto-optical and non-magnetic dielectric layers are deduced according to the coupled-mode theory. The transmission spectra of GOWs in one-dimensional magneto-photonic crystals （1 D-MPC） are investigated by the transfer matrix method. It is shown that the two sharp peaks in the 1D-MPC＇s transmission spectra can be used for high-resolution magnetic field sensing; and a comb filter with six channels can be achieved by optimizing the 1D-MPC structure and controlling the external magnetic field.     

Bandwidth-reconfigurable single-passband microwave photonic filter based on stimulated Brillouin scattering

A bandwidth-reconfigurable filter is necessary to meet the need of growing communication capacity and signal coverage frequency range. The stimulated Brillouin scattering (SBS) gain spectrum as a filter passband is used to extract desired microwave signals. Due to the fact that the passband is formed by mapping the Brillouin gain spectrum, bandwidth reconfigurability can be implemented by changing Brillouin gain linewidth. In this paper, a scheme using a 5-lines optical comb acting as a Brillouin pump is experimentally demonstrated. The spectrum of the 5-lines optical comb is extended by a binary phase shift keying (BPSK) pulse modulated signal. Experiments have shown that the 3-dB and 20-dB bandwidths of the filter are 196 MHz and 257 MHz, respectively, and its 20-dB shape factor is 1.31. The passband ripple is ~3.5 dBm with stop-band rejection of 20 dBm under 15 dBm optical pump power.     

微型轴流式血泵外磁驱动电路设计

微型轴流式血泵是目前人工心脏结构研究的热点，外磁驱动是一种新型的血泵驱动方式。文中介绍了血泵外磁驱动电路的设计方案。通过该方案能够产生双向励磁电流，可直接驱动电机以实现血泵的外磁驱动。     

An OTA-based CMOS bandpass filter for NMR applications

One of the very popular medical imaging techniques used in present-day radiology is the magnetic resonance imaging (MRI) which is based on the phenomenon of nuclear magnetic resonance (NMR) in the hydrogen atoms present in the body. There is ever-increasing research in electronic circuit design for biomedical applications using NMR. Earlier magnetic resonance imagers operated at a magnetic field strength of 0.3?T. The present imagers operate at a magnetic field of 1.5?T, the resonance frequency of the nuclei being 64?MHz. This article presents a CMOS bandpass filter (BPF) design for NMR applications. The overall BPF design is realised in 180?nm CMOS technology which occupies an active area of 24.23?×?33.125?µm² and consumes 0.165?mW of power from a 1.5?V supply.     

Tunable microwave photonic filter based on a fiber ring and erbium-doped fiber amplifier

The tunable microwave photonic filter based on a fiber ring and erbium-doped fiber amplifier （EDFA） was proposed. By introducing a section of erbium-doped fiber （EDF） into the fiber ring, the loss of the signal can be compensated by the EDFA gain through adjusting the pump power. This can largely increase the number of the effective sampling taps, and then improve the performance of the microwave photonic filter notably. When the pump power was set to be 42.7 roW, a microwave bandpass filter with the 3-dB bandwidth of 0.15 MHz, the Q factor up to 100 and extinction ratio up to 20 dB was achieved. By employing a tunable optical delay line in the above fiber ring, a tunable microwave photonic filter has been realized through tuning the length of the optical delay line. The proposed tunable microwave photonic filter can fred great applications in microwave signal processing and ROF system.     

Tunable magnetostatic surface wave demultiplexing filter/switch

A tunable frequency demultiplexing filter/switch has been realised on a magnetostatic surface wave delay line by employing both parallel-bar structure and meander line structure as output transducers together with a wideband single-line input transducer. Switching from one output terminal to the other has been obtained by changing the applied magnetic field from 57 Oe to 78 Oe at 1.1 GHz.     

1/spl times/4 optical switch based on transversal filter configuration with constant power consumption

An optical switch based on a transversal filter configuration is demonstrated. The switch consists of cascaded 3 dB optical power splitters and a phase shifter array. By using a silica-based planar lightwave circuit, a 1/spl times/4 optical switch was realised. A characteristic of the switch is that its power consumption is constant regardless of the output selection.