Electro-optic modulation in hybrid solgel doped with Disperse Red chromophore

An electro-optically active hybrid solgel doped with Disperse Red 13 has been developed by use of a simple solvent-assisted method. It permits a high loading concentration and has low optical loss at 1550 nm. A channel waveguide amplitude modulator has been fabricated by use of active and passive hybrid solgel materials. The device shows an electro-optic coefficient of 14 pm/V at 1550 nm and stable operation.     

Linear electro-optic properties of YCa4O(BO3)3

We have characterized the effective linear electro-optic coefficients of YCa4O(BO3)3 (YCOB) relative to KH2PO4 and KD2PO4 at 632.8 nm. We measured a maximum r(eff) value of 10.8 +/- 1.4 pm/V for YCOB in a transverse electric field configuration for propagation along the X or the alpha dielectric axis, with the electric field applied along the Z or the gamma dielectric axis. We also found effective coefficients of 10.7 +/- 1.0 and 3.4 +/- 0.4 pm/V for YCOB in longitudinal configurations. The remaining values of r(eff) for various transverse applied voltages were found to be less than 3 pm/V. The excellent thermomechanical properties of this crystal, coupled with moderate electro-optic coefficients, make YCOB and its isomorphs potential candidates for use as high-average-power electro-optic switches.     

弛豫铁电单晶0.93Pb(Zn1/3Nb2/3)O3-0.07PbTiO3的电光性能研究

以波长为632.8 nm的He-Ne激光作为光源,研究了三方相弛豫铁电单晶0.93Pb(Zn1/3Nb2/3)O3-0.07PbTiO3在室温下的折射率和线性电光性质.通过测量晶体的布儒斯特角,确定了单晶的两个主轴折射率:no=2.466,ne=2.488.利用改进的马赫-泽德尔干涉法测量了单晶的线性电光系数:r33=71 pm/V,r13=4 pm/V.计算得到有效电光系数rc=67 pm/V及半波电压Vπ=610 V.单晶优异的电光性能使其在激光调制与偏转领域有着巨大的应用潜力.     

Second-order nonlinear optical properties of poled coumaromethacrylate copolymers

Second-order nonlinear optical properties of newly designed and synthesized coumaromethacrylate side-chain polymers are reported. The optimum poling conditions were determined experimentally. The optimum poling temperature for these side-chain polymers is well above the glass transition temperature. The second harmonic coefficient of films poled by coronaonset at elevated temperature and the linear electro-optic coefficient of films poled by contact electrodes were measured. The stabilized value of the second harmonic coefficient, d ₃₃, at 1064nm fundamental wavelength was found to be 13 pm/V. The linear electro-optic coefficient, r ₃₃, exhibits strong dispersion ranging from 2 to 12pm/V in the wavelength range 477 to 1115 nm.     

High-frequency response and acoustic phonon contribution of the linear electro-optic effect in DAST

We present a simple method to measure the contribution from acoustic phonons to the linear electro-optic effect. A step voltage with a short rise time (600 ps) is applied to the sample, and the electro-optic response is measured in the time domain. For the organic salt 4-N, N-dimethylamino-4(?)-N(?)-methyl-stilbazolium tosylate (DAST), we obtained a negative contribution of r(a)(111) = -1.0 +/- 0.1 pm/V to the overall electro-optic coefficient of r(111) = 48 +/- 5 pm/V (lambda = 1535 nm). The electro-optic response was limited only by the rise time of the applied voltage, which corresponds to a frequency of 1 GHz.     

Transmission characteristics of multilayer films composed of electro-optic and dielectric materials

We describe the theoretical evaluation for the transmission characteristics of multilayer films composed of periodic electro-optic and dielectric materials in a variable electric field. The films are assumed to have cavity-type layer stacking structures, which work as a narrow bandpass filter, and their electro-optic material is uni-axial BaTiO₃, whose electro-optic coefficient r₅₁ is larger than 1300 pm/V. The evaluation indicates that films composed of BaTiO₃ and SiO₂ or MgO function as tunable optical bandpass filters, with a tunable range larger than 6 nm for an electric field of less than 4 V/μm.     

Spatial filtering using poled polymer etalon light modulators

Spatial filtering using poled polymer light modulators is studied. The use of a resonator structure is proposed to minimize the driving voltage. Side-chain polymer poly-orange tom-1 isophoronedisocyanate is used as a material. The measured electro-optic coefficient r ₃₃ is 23 pm/V at the wavelength of 633 nm. Spatial filtering of the input images are realized with 30 V applied voltage.     

Effective in-device r33 of 735 pm/V on electro-optic polymer infiltrated silicon photonic crystal slot waveguides

We design and fabricate a 320?nm slot for an electro-optic (E-O) polymer infiltrated silicon photonic crystal waveguide. Because of the large slot width, the poling efficiency of the infiltrated E-O polymer (AJCKL1/amorphous polycarbonate) is significantly improved. When coupled with the slow light effect from the silicon photonic crystal waveguide, an effective in-device r(33) of 735?pm/V, which to our knowledge is a record high, is demonstrated, which is ten times higher than the E-O coefficient achieved in thin film material. Because of this ultrahigh E-O efficiency, the V(π)L of the device is only 0.44?V?mm, which is to our knowledge the best result of all E-O polymer modulators.     

低阈值极化电压玻璃光波导电光效应的研究(英文)

采用热极化技术对掺锗玻璃条形光波导进行极化,通过光纤连接(单模)的Mach ZehnderInterferometer系统测量条形波导内诱导出的电光效应,系统地研究了大气环境下极化条件(极化温度、极化时间、极化电压)对电光效应的影响.结果表明:在最佳极化条件下(406℃、-2.4kV、20min),波导内的电光系数为rTM=0.059±0.001pm/V,rTE=0.053±0.001pm/V,且波导结构中存在一个较低的阈值极化电压(100V)和阈值极化温度(80℃),此时在波导样品内仍能被激发出可观察的电光效应;实验还发现采用负极化诱导方式产生的电光系数较正极化提高15%左右.     

Waveguide electro-optic modulator in fused silica fabricated by femtosecond laser direct writing and thermal poling

An integrated electro-optic waveguide modulator is demonstrated in bulk fused silica. A Mach-Zehnder interferometer waveguide structure is fabricated by direct writing with a femtosecond laser followed by thermal poling. A 20 degrees electro-optic phase shift is achieved at an operating wavelength of 1.55 microm with an applied voltage of 400 V and an interaction length of 25.6 mm, which correspond to an estimated effective electro-optic coefficient of 0.17 pm/V for the TE-polarized mode.     

Characterization of second and third order optical nonlinearities of ZnO sputtered films

We measured the second and third order optical nonlinearity of zinc oxide, grown on glass substrates by the ion beam sputtering technique. Second and third harmonic generation measurements were performed by means of the rotational Maker fringes technique for different polarization configurations, thus allowing the determination of all non-zero components of the second order susceptibility at three different fundamental beam wavelengths, i.e., 1064 nm, 1542 nm and 1907 nm. The dispersion of the nonlinear optical coefficients has been evaluated, while the nonlinear optical coefficients were found to range between 0.9 pm/V and 0.16 pm/V for d₃₃, 0.53 pm/V and 0.08 pm/V for |d₁₅|, 0.31 and 0.08 pm/V for |d₃₁|, with increasing wavelength. Finally, one third order susceptibility, χ_ijkl ⁽³⁾, has been determined by third harmonic generation measurements at a fundamental wavelength λ=1907 nm and a value for χ₃₃₃₃ ⁽³⁾ of 185×10^-20 m²/V² has been found. PACS 42.65.An; 42.65.Ky; 42.70.Nq     

低阈值极化电压玻璃光波导电光效应的研究

采用热极化技术对掺锗玻璃条形光波导进行极化,通过光纤连接 (单模) 的Mach Zehnder Interferometer 系统测量条形波导内诱导出的电光效应,系统地研究了大气环境下极化条件(极化温度、极化时间、极化电压)对电光效应的影响.结果表明:在最佳极化条件下(406℃、-2.4 kV、20 min),波导内的电光系数为r_TM=0.059±0.001 pm/V, r_TE=0.053±0.001 pm/V,且波导结构中存在一个较低的阈值极化电压(100 V)和阈值极化温度(80℃),此时在波导样品内仍能被激发出可观察的电光效应;实验还发现采用负极化诱导方式产生的电光系数较正极化提高15%左右.     

Optimizing Design for the Traveling Wave Electrodes in Low-Drive High-Speed Electro-Optic Polymer Modulators

Electro-optic (EO) polymer modulators are very promising in the realization of cost-effective and high-performance optical transmissions. In this article, general strategies and specific designs of the traveling wave electrodes in EO polymer modulators were presented to reduce the modulator drive power while maintaining a broadband response. The optimum device parameters and corresponding conditions were estimated using finite element method based on electrode design. In calculating the results, the comprehensive characteristics of polymer modulator with 1.21 V half-wave voltage and 91 GHz bandwidth was demonstrated with electro-optic interaction length is 20 mm, electro-optic coefficient is 55 pm/V, and operation wavelength is 1.319 μm. These results agree with the 0.8 V half-wave voltage and 30 mm electro-optic interaction length reported in Science. In the five designs presented, a hybrid electrode structure combining CPW and microstrip lines were advanced. The characteristics of this structure are like that of microstrip lines with a single-arm electrode on one arm of the waveguide, but it solves the problem of microstrip to coaxial line transition and corona polarization.     

A 2 by 2 wavelength tunable Fabry-Perot filter by using an electro-optic polymer film

A tunable Fabry-Perot (F-P) filter by using electro-optic polymer film is proposed. The electro-optic polymer is alkoxysilane dye (ASD)/SiO2-TiO2 hybrid material, whose electro-optic coefficient γ33 is about 5 pm/V. The wavelength tuning range of 3.8 nm under 400-V DC voltage and the nonlinear characteristic with the electric field have been obtained via electro-optical properties of polymer. Both of polymer film fabrication and F-P filter design have been introduced. The tunable F-P filter is designed for the application of two-input/two-output port wavelength-selective optical switch. Also, some problems have been discussed in this letter.     

一种具有高二阶非线性椭圆芯中空光纤

提出并制造一种新颖的椭圆芯中空光纤,采用热极化方法使其具有高二阶非线性,可用作相位调制器。该光纤在300℃温度、大于1×108 V/m强电场和9cm有效电极长度条件下热极化30min后,产生大的线性电光相移。基于双椭圆芯中空光纤构建一种纤内马赫-曾德尔干涉仪,通过观察干涉条纹的移动来评估相移,最终得到1.16pm/V的高二阶非线性系数和0.52pm/V的线性电光系数。该技术具有简单、灵活的特点,可以用来制作高电光系数器件,降低制作成本,并能进一步提高全光纤器件的集成度。     

Integrated optical Mach-Zehnder modulator based on polycrystalline BaTiO3

Good-quality polycrystalline BaTiO3 thin films are deposited on MgO substrates by pulsed laserdeposition. The deposition parameters are optimized to achieve optical-quality films with an attenuation coefficient of 4 dB/cm at the 633-nm wavelength. Thin-film electro-optic Mach-Zehnder modulators are fabricated with standard lithography and ion-beam etching. The waveguides patterned by lithography are the ridge type, and they ensure single-mode propagation in the wavelength range of 633-1550 nm. An electro-optic coefficient of 22 pm/V is estimated for the polycrystalline BaTiO3 films.     

M-Z型极化DANS聚合物电光波导强度调制器研究

研究了Mach-Zehnder型极化聚合物电光波导强度调制器的制备工艺.器件采用DANS (4-dimethylamino-4′nitro-stlibene)聚合物为电光波导材料,由电光波导层、上下介质缓冲层、上下金属电极层构成五层波导结构.对五层光波导各层之间的光学、化学以及微加工工艺的相互兼容性进行了深入研究.采用紫外光漂白方法制备出侧壁光滑的条波导,采用钨丝电晕极化方法对DANS聚合物波导进行有效极化,使其具有电光特性.通过优化器件制备工艺,研制出工作波长为1300 nm的M-Z型电光波导强度调制器原型器件.实验测得器件半波电压约为10 V,调制带宽约为1 GHz.     

Electro-optic properties of hybrid solgel doped with a nonlinear chromophore with large hyperpolarizability

We report the electro-optic properties of hybrid silica solgel doped with a nonlinear chromophore with large hyperpolarizability. Electro-optic coefficients of higher than 30 pm/V have been obtained. Moreover, the electro-optic coefficients have good temporal stability and show promise for the development of high-speed electro-optic devices.     

Hybrid Si-LiNbO₃ microring electro-optically tunable resonators for active photonic devices

Hybrid Si-LiNbO? electro-optic tunable ring resonators have been proposed and demonstrated as a path to achieving ultracompact and high-speed electro-optic devices. Free standing single crystal LiNbO? microplatelets (~mm long and ~1 μm thick) were obtained from a z-cut LiNbO? substrate by ion implantation and thermal treatment. The platelets were transferred and thermally bonded on top of Si resonators that were fabricated in a Si-on-insulator platform by a 0.18 μm standard complementary metal-oxide-semiconductor process. For the hybrid microring resonator, a free spectral range of 16.5 nm, a finesse F of ~1.67 × 102, a Q-factor of ~1.68 × 10?, and an effective r coefficient of ~1.7 pm/V were achieved for the TE mode. These values are in good agreement with the calculated results.     

Optimizing Design for the Traveling Wave Electrodes in Low-Drive High-Speed Electro-Optic Polymer Modulators

Electro-optic (EO) polymer modulators are very promising in the realization of cost-effective and high-performance optical transmissions. In this article, general strategies and specific designs of the traveling wave electrodes in EO polymer modulators were presented to reduce the modulator drive power while maintaining a broadband response. The optimum device parameters and corresponding conditions were estimated using finite element method based on electrode design. In calculating the results, the comprehensive characteristics of polymer modulator with 1.21 V half-wave voltage and 91 GHz bandwidth was demonstrated with electro-optic interaction length is 20 mm, electro-optic coefficient is 55 pm/V, and operation wavelength is 1.319 μm. These results agree with the 0.8 V half-wave voltage and 30 mm electro-optic interaction length reported in Science. In the five designs presented, a hybrid electrode structure combining CPW and microstrip lines were advanced. The characteristics of this structure are like that of microstrip lines with a single-arm electrode on one arm of the waveguide, but it solves the problem of microstrip to coaxial line transition and corona polarization.