用视频摄像技术测定纳米晶聚合物复合薄膜的传输损耗

研制了一种新的钛酸铅 聚醚醚酮 (PT PEK c)纳米晶聚合物复合薄膜 ,用视频摄像技术准确、实时地分析了这种复合薄膜的传输损耗。该方法包括一架高分辨率的数码相机和相应的数据处理软件 ,以及棱镜耦合系统 ,其测量范围为 0 5～ 10 0dB/cm ,用这种方法测得PT PEK c纳米晶聚合物复合薄膜在 6 33nm处的传输损耗为 3 0 9dB/cm。     

Scattering loss reduction in polymer waveguides by reflowing

A polymer channel waveguide was fabricated by reactive ion etching. Loss measurements were performed on this waveguide before and after reflowing. The waveguide loss decreases from 3 to 1 dB/cm by heating the sample slightly above the glass transition temperature of the core material. This result in channel loss is very close to the measured film losses of 0.8 dB/cm.     

Second-order nonlinearity of a disazo dye attached polymer

Second-order optical nonlinearity of a disazo dye attached polymer was investigated. The optical loss of the film is 1.5 dB/cm at 633 nm. The second-order nonlinear coefficient chi /sup (2)/ of the poled film is comparable to that of lithium niobate at 1.55 mu m. The chi /sup (2)/ is greater than that of a monoazo dye attached polymer throughout the fundamental wavelength of 1.06-1.70 mu m.<>     

Optical transmission losses in polycrystalline silicon strip waveguides: Effects of waveguide dimensions, thermal treatment, hydrogen passivation, and wavelength

Signal propagation delays dominate over gate delays in the ever-shrinking ultra large scale integrated (ULSI) circuits. Consequently, silicon-based monolithic optoelectronic circuits (SMOE) with their light speed signal propagation can provide unique advantages for future generations of microprocessors. For such SMOE circuits, we need optical interconnects compatible with silicon technology. Strip waveguides consisting of polycrystalline silicon (polySi) clad with SiO₂ offer excellent optical confinement and ease of fabrication that are ideal for such interconnect applications. One major challenge with using this material system, however, is its insertion loss. In this paper we provide techniques for minimizing optical transmission losses in polySi strip waveguides. Our previous work using polySi strip waveguides, showed an optical transmission loss of 15 dB/cm at λ=1.55 μm, which is a communication wavelength of choice in optical fibers because it represents an absorption minimum. Similar measurements in crystalline silicon strip waveguides¹ yielded transmission losses of less than 1 dB/cm. Hitherto, in decreasing loss from 77 dB/cm to 15 dB/cm, we had minimized loss from surface scattering by improving the film surface morphology, and decreased bulk absorption with hydrogen passivation. In this paper we report a further reduction in the residual bulk loss from 15 dB/cm to 9 dB/cm. By experimenting with different waveguide core dimensions, we find that the contribution of bulk loss towards net transmission loss decreases with waveguide core thickness. Additionally, high temperature treatment provides strain relief in the polySi, decreasing transmission loss. Annealing in an oxygen ambient is not recommended because it always increases transmission loss. Hydrogen passivation improves transmission, attributable to passivation of light-absorbing dangling bond defect sites present at polySi grain boundaries. Together, these methods have resulted in the lowest measured loss value of 9 dB/cm at λ=1.55 μm. Since integrated SiGe and Ge photodetectors are more efficient at shorter wavelengths like λ=1.32 μm, transmission loss is also measured at λ=1.32 μm. Losses at the two wavelengths (1.32 μm and 1.55 μm) are similar when defects and stress in the waveguides are minimized.     

Polymeric variable optical attenuator based on long range surface plasmon polaritons

Proposed is a polymeric variable optical attenuator based on long range surface plasmon polaritons (LRSPPs) along a thin metal stripe embedded in polymers. The device is operated by controlling radiation loss of the LRSPP mode resulting from the temperature gradient of the polymer cladding caused by a heater. For guiding LRSPPs and efficient coupling of singlemode fibres, gold stripes 20 nm thick, 4 /spl mu/m wide and 1 cm long are utilised. To obtain a long physical lifetime, the heater is formed on the top of the polymer cladding with a 200 nm Au film which is about ten times thicker than the thin metal waveguide. The fabricated device is characterised at a wavelength of 1.55 /spl mu/m, exhibiting high attenuation of less than 30 dB with an operating power of 100 mW. A fibre-to-fibre total insertion loss of 6.1 dB is achieved when using singlemode fibres.     

Low-loss electrooptic BaTiO/sub 3/ thin film waveguide modulator

A strip-loaded electrooptic waveguide modulator based on an epitaxial BaTiO/sub 3/ thin film was fabricated and characterized for the first time. The strip-loaded waveguide structure greatly improves waveguide propagation and polarization-dependent loss performance. A propagation loss of 1.1 dB/cm and polarization dependent loss of 0.1 dB/cm were measured. The electrooptic waveguide modulator exhibited a half-wave voltage-interaction length product of 4.5 V /spl middot/ cm at a wavelength of 1542 nm. The measured effective electrooptic coefficient of the as-grown BaTiO/sub 3/ waveguide modulator was 38 pm/V. The experimental results indicate that a strip-loaded thin film waveguide modulator is suitable for photonic applications.     

Multimode deposited silica waveguide and its application to an optical branching circuit

A fabrication procedure has been developed for multimode deposited silica waveguide (DS guide), consisting of uniform and thick glass layer formation for core and cladding, and amorphous Si mask film for reactive sputter etching. The embedded multimode DS guide with a square core cross section has a transmission loss of 1.3 dB/cm at 633 nm wavelength. Waveguide parameters, such as core dimension, refractive index, and index difference, are similar to those of a multi-mode silica fiber. A multimode optical branching circuit with eight output ports was demonstrated by the above fabrication procedure. Excess insertion loss was 2 dB.     

含氟聚酰亚胺有机聚合物波导的制备

采用含氟单体4,4＇-（六氟异丙基）-苯二酸酐（6FDA）、5,5＇-（六氟异丙基）-二-（2-氨基苯酚）（6FHP）及二氨基二苯醚（ODA）合成了含氟聚酰亚胺共聚物材料,对材料的化学和光学性能进行了表征.共聚物材料在溶液状态下用旋涂法获得了较高质量的共聚物薄膜,并在此基础上采用先进的光波导工艺技术将该材料制备成条波导,测试结果表明该波导在光通信波段1550nm处的平均传输损耗小于0.66dB/cm,局部损耗在0.2dB/cm,进一步改进后有望获得性能优异的光电子器件.     

Stress-induced polymer waveguides operating at both 1.31 and 1.55 /spl mu/m wavelengths

Metal-defined polymer optical waveguides have been demonstrated for the first time. A metal strip patterned on top of a polymer slab waveguide causes a stress-induced refractive index change, providing lateral optical mode confinement within the core layer. Fabricated waveguides exhibit low propagation loss values of 1.1 dB/cm at 1.31 /spl mu/m and 1.3 dB/cm at 1.55 /spl mu/m for both TE and TM polarisations.     

Low-loss proton-exchanged waveguide in MgO-doped LiNbO3fabricated with pyrophosphoric acid using Ta2O5protective mask

The authors describe low-loss proton-exchanged channel waveguides in MgO-doped LiNbO₃. The authors demonstrate the application of a Ta₂O₅ film for the protective mask material in proton-exchanging instead of a Ta film in order to reduce the propagation loss. A Ta₂O₅ sputtered film was applied as a protective mask with pyrophosphoric acid. The propagation loss of the waveguide, measured with laser diode light (λ=0.83 μm) was 0.5 dB/cm. It is shown that the use of a Ta₂O₅ mask reduces the propagation loss compared with the use of a Ta mask (1.5 dB/cm)     

聚合物复合薄膜DR13/PMMA的制备及其光学特性

薄膜的厚度、折射率和传输损耗等参数在电光系数的确定和光波导器件的设计和制作过程中都是重要的参考数据。采用旋涂法制备了三种不同质量比的偶氮化合物染料分散红13(DR13)与聚合物聚甲基丙烯酸甲酯(PMMA)复合薄膜;利用分光光度计测量样品的吸收光谱;利用棱镜耦合仪测量了薄膜的厚度和折射率,并对不同波长下的折射率进行拟合得到折射率色散曲线;采用视频摄像技术研究样品的光传输特性,利用自己编写的计算机程序来处理其实验结果。DR13/PMMA复合薄膜在300nm和500nm处有两个大的吸收峰,而在其他波段,尤其是在通信波段没有明显吸收。薄膜的膜厚大约为1~2μm,其折射率随着质量比的增加而增大,随着激光波长的增大而降低,膜厚和折射率的误差分别为3.2×10-1μm和1.5×10-3。三种质量比(10%,15%和20%)的薄膜传输损耗分别为1.5269dB/cm,2.7601dB/cm和3.6291dB/cm,可以看出随着DR13质量比的增大,光传输损耗也逐渐增大,即DR13的含量对于传输损耗的影响较大。     

低阻硅基厚膜聚酰亚胺上共面波导的损耗特性

制备了一种低阻硅基厚膜聚酰亚胺上的高性能共面波导传输线 ,并从理论上分析了传输线损耗的成因及其计算方法。聚酰亚胺膜厚 1 1 .5 μm的低阻硅 (0 .5 Ω·cm)上的共面波导传输线在 1 0 GHz下插入损耗为3 .5 d B/cm。然而 ,相同衬底上 ,无聚酰亚胺膜的共面波导传输线在 1 0 GHz下插入损耗为 5 0 d B/cm,损耗特性明显比前者差。测试结果表明聚酰亚胺层的介入能有效地改善传输线的损耗特性 ,且损耗随着聚酰亚胺膜厚的增加而降低。     

High-frequency, low-crosstalk modulator arrays based on FTC polymersystems

A novel electro-optic polymer Furan TetraCyano Indane (FTC) has been utilised in the fabrication of low V_π, high-speed travelling-wave Mach-Zehnder modulator arrays. The modulators were realised with microstrip transmission lines that were optimised resulting in a line loss of 3.64 dB/cm at 40 GHz. Mach-Zehnder modulators based on this design with 1.6 cm interaction length resulted in devices with V_π<5 V and a reasonably fiat frequency response up to 40 GHz. Electrical crosstalk measurements were also conducted on adjacent modulators separated by 400 μm in a modulator array. Without the implementation of any crosstalk reduction techniques, the measurement results indicated a crosstalk level of <-40 dB in the frequency band between 0 and 40 GHz. These impressive results were a consequence of the low dielectric constant of the polymer material at microwave frequencies and of the small lateral dimensions of the microstrip lines     

Polymer-Based Long-Range Surface Plasmon Polariton Waveguides for 10-Gbps Optical Signal Transmission Applications

We present characteristics of very thin Au strip waveguides based on long-range surface plasmon polaritons (LR-SPPs) along thin Au strips embedded in polymers. We also report a 10 Gbps optical signal transmission via LR-SPPs with the pig-tailed Au strip waveguide at a telecommunication wavelength of 1.55 mum. We limited the thickness, width, and length up to ~20 nm, ~ 10 mum, and ~5 cm, respectively, for practical applications. At 1.55 mum, loss properties of the Au strip waveguides were theoretically and experimentally evaluated with thickness, width and cladding material. The lowest propagation loss of ~1.4 dB/cm was experimentally obtained with the 14-nm-thick and 2-mum-wide Au strip. With a single-mode fiber, the lowest coupling loss of less than 0.1 dB/facet was achieved with the 14-nm-thick and 7.5-mum-wide Au strip. The lowest insertion loss was obtained 7.7 dB with the 14-nm-thick, 5-mum-wide, and 1.5-cm-long Au strip. The propagation loss was improved approximately 30% for the 17-nm-thick Au strip with lowering the refractive index of the cladding polymer by 0.01. In the 10 Gbps optical signal transmission experiment, the LR-SPP waveguide exhibits an excellent eye opening and a 2.2 dB power penalty at 10^-12 bit error rate. These all results indicate that the LR-SPP waveguide is a potential transmission line for optical interconnects to overcome inherent problems in electric interconnects.     

Influence of water sorption on acrylic polymer waveguide loss

The influence of water sorption on acrylic polymer waveguides was studied by measuring the loss changes in the atmosphere at 13 to 98% RH. The absorption peak at 1.41 μm increased from 0.5 to 2 dB/cm due to water sorption. This peak resulted in a small loss change of 0.03 dB/cm at 1.3 μm, which was successfully measured using a 57 cm waveguide with a loss of around 0.1 dB/cm. Relationships between loss change and water sorption were also revealed by measuring the water content of the polymers     

Integration of an electrooptic polymer in an integrated opticscircuit on silicon

This paper presents the joining of active nonlinear polymer waveguides with passive silicon nitride waveguides (SiO₂-Si ₃N₄-SiO₂) to form an integrated Mach-Zehnder modulator with a lateral electrode configuration on a silicon substrate. Passive and active waveguides are based on a silicon-nitride-strip guiding structure. In the active waveguide a nonlinear polymer layer is used to obtain an index modulation via the electrooptic effect. Despite the silicon nitride strip based guiding structure, 63% of the energy of the fundamental mode is guided in the nonlinear polymer (provided by Flamel Technology, Venissieux, France). Poling with field strengths up to 75 V/μm applied to the lateral electrodes has been employed to orient the chromophores. A half wave voltage of 35 V has been measured for an electrooptic coefficient of 5.8 pm/V at a wavelength of 1.3 μm. Optical loss measurements have been done on polymer and passive waveguides. The best results have been 1.8 dB/cm for the active and 0.78 dB/cm for the passive waveguides leading to a total loss of 6 dB for a modulator with an interaction length of 2.5 cm. The coupling loss between a laser diode and the passive waveguide structure was measured to be at least 4.6 dB using a microscope objective and piezo-electric displacement elements. Stability tests under atmospheric conditions have shown a decrease of the electrooptic coefficient which might be due to the hygroscopic behavior of the active polymer. The bandwidth of the modulator has been determined to be 4 MHz     

Polyimide/Ta2O5/polyimide antiresonantreflecting optical waveguides

A novel antiresonant reflecting optical waveguide (ARROW) fabricated using both the organic and dielectric thin film technologies is presented for the first time. The ARROW consisted of the fluorinated polyimide and tantalum pentoxide (Ta₂O₅) hybrid layers deposited on a Si substrate. For TE polarized light, the propagation loss of the waveguide as low as 0.8 dB/cm is obtained at 632.8 nm. The propagation loss for TM polarized light is 2.7 dB/cm. Some design considerations of the hybrid ARROW are also discussed in this work     

Single-mode optical Y-branching circuit using deposited silica guides (DS guides)

A new optical Y-branching circuit using embedded single-mode glass waveguides is presented. The glass waveguides were made by depositing core glass on a silica substrate after forming grooves to contain the core (DS guides). Waveguide transmission loss is 0.6 dB/cm. The loss caused at a branching point is 0.13 dB when the branching angle is 0.3°.     

Photonic integrated circuits by DUV-induced modification of polymers

The results achieved with polymer Y-splitters, codirectional couplers, and multimode interference couplers, realized by deep ultraviolet lithography are presented. The devices are designed and fabricated for the 1.55-/spl mu/m wavelength region and have a waveguide loss of 1 dB/cm. The waveguide width is 7.5 /spl mu/m. The fiber-chip coupling loss is 0.5 dB per facet. The polarization-dependent loss is <0.15 dB.     

电阻率对硅衬底微波传输特性影响分析

针对传统硅衬底介质损耗大的现象,通过软件电磁仿真手段分析不同电阻率硅衬底上微带线的传输特性,系统研究电阻率变化对硅衬底微波传输特性的影响,并与基于MEMS三维加工的低阻硅衬底进行比较。在30 GHz频率范围内,当硅衬底电阻率从10Ω·cm提升至4 000Ω·cm时,微带线插入损耗从20 dB/cm降低至0.6 dB/cm。电阻率大于100Ω·cm的高阻硅衬底微波传输特性优于带MEMS空腔的10Ω·cm低阻硅衬底。结果表明提升电阻率可有效降低硅衬底微波传输损耗,结合低成本成熟工艺等优点,高阻硅衬底具有广阔的微波集成应用前景。