铌酸锂光纤型行波调制器研究

以LiNbO3光纤作为通光部分,Si2N2O为衬底分别取代了传统波导电光调制器的中Ti:LiNbO3波导和铌酸锂衬底设计了带宽为95.49 GHz铌酸锂光纤型调制器.今利用有限元法分析SCPS电极结构下该铌酸锂光纤调制器的性能.研究结果表明,该新型调制器可以在很宽的频带内实现调制速度的匹配和阻抗匹配,半波驱动电压为2.56 V,特性阻抗为55.3Ω.     

光纤-波导五维对接误差对耦合损耗的影响

扩钛铌酸锂电光波导调制器在光纤通信的信息中有关重要的应用,而光纤与波导的耦合是调制器封装中关键的一步,它直接影响调制器的插入损耗。迄今为止,对于直接对接耦合法只给出了三维的分析结果,本文利用复数高斯积分法给出了五维分析的曲线,对对接耦合提出了定量要求。     

单晶铌酸锂薄膜光波导的制备研究

为了优化单晶铌酸锂薄膜光波导的性能,研究了基于单晶铌酸锂薄膜材料的光波导刻蚀工艺.虽然Ar+物理刻蚀能够达到最高95 nm/min的刻蚀速率,但难以获得光滑的波导侧壁,且以Cr作为掩膜的刻蚀选择比为1∶1,这意味着较差的选择性使其难以实现铌酸锂的深刻蚀.而采用反应离子刻蚀(RIE)得到的刻蚀速率较低,但是以Cr作为掩膜...     

宽带低压15GHz铌酸锂电光调制器

报导了国内首例宽带，低压铌酸锂电光调制器的研究结果。用傅利叶级数方法设计了长电极，厚金电极和厚ＳｉＯ２缓冲层的Ｍ－Ｚ光波导强度调制器，制成的调制器为实用化带尾光纤包装式器件，在１．５５μｍ工作波光下，其性能指标为３ｄＢ光调制带宽１５ＧＨｚ，半波电压５．６Ｖ，消光比２１ｄＢ。     

高掺锌富锂铌酸锂体抗光损伤能力的研究

以Czochralski法生长Zn(6mol%)：LiNbO3,Li/Nb=0.94,0.97,1,1.02。测试晶体的光损伤阈值。采用质子交换法制作高掺锌富锂铌酸锂晶体光波导,研究了它们的抗光损伤能力。     

高掺锌富锂铌酸锂晶体抗光损伤能力的研究

以Czochralski法生长Zn(6mol%): LiNbO3, Li/Nb=0.94, 0.97, 1, 1.02.测试晶体的光损伤阈值.采用质子交换法制作高掺锌富锂铌酸锂晶体光波导,研究了它们的抗光损伤能力.     

光波导位相调制技术产生多波长光源

用Matlab软件模拟分析了高频光波导电光位相调制器的输出光谱特性。结果表明,在一定频率的微波源作用下,单色光通过光波导位相调制器后会产生光频谱展宽,展宽光谱中包括中心波长及各阶光边波带。随位相调制深度加大,边波带数目增多,光谱展宽增大;位相调制深度为3.3时,10dB展宽光谱中含边波带数为8个。实验制作了光波长1．55μm、微波频率10GHz的铌酸锂电光波导位相调制器;输出光谱中可清楚观察到正负三阶等频率间隔的边波带,即可实现七路光源输出,由此提出并验证了光波导位相调制技术用作多波长光源的可能性。利用位相调制器的光频谱展开得到多波长光源,具有成本低．易实现、促进系统集成等优点,有良好的应用前景。     

掺铒铌酸锂调Q波导激光器的设计和理论分析

掺铒铌酸锂调Q波导激光器的设计和理论分析     

基于电吸收调制器的40Gbit/s光发射单元

采用电吸收调制器(EAM)作为电光调制器件,实现了基于电时分复用(ETDM)工作方式的40Gbit/s光发射单元,并采用SDH 42.836(Gbit/s标准数据库)对其进行了测试实验.在42.836Gbit/s数据率下,其输出光信号消光比达10dB以上,光眼图信噪比约11.4,抖动方均根值1.3～1.4ps;在G.652光纤中传输1km后,消光比大于9dB,光眼图信噪比约7.1,抖动方均根值为1.4～1.5ps,这些技术指标达到了实用要求.     

铌酸锂粉体的制备和研究进展

铌酸锂具有居里温度高、自发强度大等优点,是一种重要的压电铁电材料,在电光装置和声表面装置中有着广泛的应用。本文中分析了铌酸锂粉体的国内外研究进展,简要介绍了合成铌酸锂粉体的几种方法,如sol-gel法、沉淀法、水热法等,以及在合成结构均一、纯度高、颗粒尺寸小的铌酸锂粉体方面的研究及其应用现状。     

Theoretical waveguide optimization in a Ti:LiNb0(3) Mach-Zehnder modulator by Mg diffusion

Magnesium diffusion can be used to optimize the characteristics and performance of a Ti:LiNbO(3) Mach-Zehnder modulator. Suitable use of titanium/magnesium double diffusion reduces fiber-waveguide coupling loss, minimizes the modulator size by increasing the bend radius of curvature without increasing bend losses, and decreases separation of the modulator arms. The proposed method also makes it possible to reduce the modulating voltage by improvement of guided-wave lateral confinement. Secondary ion mass spectrometry and 771-line techniques are used to characterize Ti/Mg:LiNbO(3) waveguides. A numerical optimization procedure based on the full vectorial beam-propagation method is presented.     

Characterization of near-stoichiometric Ti:LiNbO(3) strip waveguides with varied substrate refractive index in the guiding layer

We have demonstrated the possibility that near-stoichiometric Ti:LiNbO(3) strip waveguides are fabricated by carrying out vapor transport equilibration at 1060 degrees C for 12 h on a congruent LiNbO(3) substrate with photolithographically patterned 4-8 microm wide, 115 nm thick Ti strips. Optical characterizations show that these waveguides are single mode at 1.5 microm and show a waveguide loss of 1.3 dB/cm for TM mode and 1.1 dB/cm for TE mode. In the width/depth direction of the waveguide, the mode field follows the Gauss/Hermite-Gauss function. Secondary-ion-mass spectrometry (SIMS) was used to study Ti-concentration profiles in the depth direction and on the surface of the 6 microm wide waveguide. The result shows that the Ti profile follows a sum of two error functions along the width direction and a complementary error function in the depth direction. The surface Ti concentration, 1/e width and depth, and mean diffusivities along the width and depth directions of the guide are similar to 3.0 x 10(21) cm(-3), 3.8 microm, 2.6 microm, 0.30 and 0.14 microm(2)/h, respectively. Micro-Raman analysis was carried out on the waveguide endface to characterize the depth profile of Li composition in the guiding layer. The results show that the depth profile of Li composition also follows a complementary error function with a 1/e depth of 3.64 microm. The mean ([Li(Li)]+[Ti(Li)])/([Nb(Nb)]+[Ti(Nb)]) ratio in the waveguide layer is about 0.98. The inhomogeneous Li-composition profile results in a varied substrate index in the guiding layer. A two-dimensional refractive index profile model in the waveguide is proposed by taking into consideration the varied substrate index and assuming linearity between Ti-induced index change and Ti concentration. The net waveguide surface index increments at 1545 nm are 0.0114 and 0.0212 for ordinary and extraordinary rays, respectively. Based upon the constructed index model, the fundamental mode field profile was calculated using the beam propagation method, and the mode sizes and effective index versus the Ti-strip width were calculated for three lower TM and TE modes using the variational method. An agreement between theory and experiment is obtained.     

TE,TM模入射对光纤CATV外调制发射机性能的影响

从理论上分析了ＣＡＴＶ外调制发光射机在ＴＥ,ＴＭ两种模式入射下的性能及对比,对Ｘ切ＬｉＮｂＯ３波导调制器,在相同的入射光功率和射频电功率条件下,如果调制器对两种模式的插入损耗相同,则ＴＥ模比ＴＭ模的ＣＮＲ大１０ｄＢ,ＣＳＯ小１０ｄＢ,而ＣＴＢ大２０ｄＢ,因而从总体性能考虑,以ＴＥ模入射为佳,实验结果和理论分析是一致的。     

Properties of nonblocking single-substrate optical space switching networks constructed from directional couplers

Some of the properties of single-substrate nonblocking optical space switching networks that are constructed from directional couplers, waveguide bends, and waveguide crossovers are considered. Expressions are given for the ratio of network output signal to cross talk, insertion loss, and total switch count for ten different structures. Based on these expressions, estimates of the maximum switch sizes attainable are made. Consideration is also given to the factors that govern the practical implementation of such structures, and this shows that rearrangeably nonblocking single-substrate switches of up to 128 × 128 should be possible if technologies other than Ti:LiNbO(3) are used.     

Optimized half-wave voltage and insertion loss in a strip-loaded waveguide electro-optic polymer modulator

A strip-loaded waveguide, electro-optic modulator was designed and analyzed in terms of single mode conditions, optical loss due to the metal electrodes, modulation efficiency, and mode size. Two designs were compared: Design 1 optimized the half-wave voltage (V(π)=1.1 V) with a nearly symmetric waveguide by maximizing modulation efficiency and minimizing the overall thickness of the waveguide; Design 2 optimized the insertion loss by reducing coupling loss by 4.6 dB via a strongly asymmetric waveguide that maximizes the overall mode size to most efficiently overlap with a single mode fiber. Design 2 also has a favorable half-wave voltage (V(π)=1.75 V). Some general guidelines in the selection of cladding layers in a detailed design of a poled-polymer electro-optic modulator incorporating a strip-loaded waveguide structure are suggested.     

Narrowband Bragg reflectors in Ti:LiNbO3 optical waveguides

Bragg grating reflectors etched in amorphous silicon overlay films have been integrated with Ti:LiNbO3 optical waveguides to obtain a narrow (0.05 nm) reflectance spectrum with a > 20 dB dip in the transmittance spectrum. These results were realized at a wavelength of 1542.7 nm for TE polarization on an x-cut, y-propagating substrate with gratings etched to a depth of approximately 93 nm in a 105 nm thick silicon film over a length of 12.5 mm. The reflectance in the channel waveguides is found to be strongly dependent on the depth of the etched grating. The effect of the Bragg waveguide loss factor on the transmittance and reflectance spectra is investigated by using a model for contradirectional coupling that includes an attenuation coefficient. The values for coupling constants kappa and amplitude attenuation constants alpha of samples etched for different time durations to control the grating depths are obtained from the model through the use of the depth of the dips in the transmittance spectra and the spectral widths of the reflectance peaks. It is concluded that the corrugated Si overlay film increases the insertion loss by approximately 2.7 dB, and the loss is not significantly affected by the grating depth.     

Fabrication and analysis of a low-loss in-fiber active polymer waveguide

We present a method for fabricating an in-fiber electro-optic polymer waveguide within a D-shaped optical fiber. A combined process of selective chemical etching and spin coating creates a 2-cm in-fiber poly(methyl methacrylate)-DR1 dye polymer waveguide section with an overall insertion loss of micro 1.6 dB at 1550 nm. Numerical simulations show that, for in-fiber polymer waveguides to have low loss, the polymer layer's thickness must be kept below a certain value so that it will not support slab waveguide modes. Long transition regions between the unetched fiber and the polymer waveguide section also reduce loss. We analyze the efficiency of an in-fiber polymer waveguide by simulating its theoretical performance as an electro-optic modulator.     

调频光纤陀螺中的集成光学频移器

报道了一种在Ｙ一切铁扩散ＬｉＮｂＯ３平板光波导上制作的调频光纤陀螺用集成光学频移器。它由一对球面波导短程透镜和两个声表面波声光调制器组成。频移宽度为１０ＭＨｚ，调制器的中。Ｃ频率为１０７ＭＨｚ，驱动功率为２００ｍＷ。     

M－Z型铌酸锂高速调制器

报道了采用行波电极结构的偏振型和与偏振无关型Ｔｉ：ＬｉＮｂＯ３高速强度调制器，其中与偏振无关的高速强度调制器是首次研制成功。