Developments in optical waveguide fabrication by the outside vapor deposition process

Improvements in optical fiber fabrication made over the last two years using the outside vapor deposition (OVD) process are reported. Advances have been made in the areas of optical and mechanical performance for existing products, dopant changes, and single-mode fiber designs. A multimode fiber having no P2O5in the core has been demonstrated which also exhibits uniform forward and cutback bandwidth-length dependence and improved resistance to the effects of hydrogen. Data is also presented on a dispersion-shifted single-mode fiber made using the segmented core approach which has recently been put into production.     

Fabrication of SiO2-TiO2 glass planar optical waveguides by flame hydrolysis deposition

Low-loss SiO2TiO2 planar waveguides of 0.1 dB/cm have been fabricated by flame hydrolysis deposition suitable for mass-production. A CO2 laser was used to make a stripe waveguide structure for loss measurements.     

Fabrication of optical inverted-rib waveguides using UV-imprinting

In this paper we introduce a fabrication process for polymer rib waveguides that uses UV-imprint lithography. In the structure of an inverted-rib waveguide, the lower cladding of the waveguide is patterned by UV-imprinting and the waveguiding layer is subsequently spin-coated. That makes the thickness of the formed slab layer on the rib waveguide controllable by tuning the spin-coating parameters. The fabrication process utilizes two steps of UV-imprinting. The first one is to form a rigid polymer mold from positive tone photoresist. The second one is to pattern the waveguide lower cladding with the formed polymer mold. Through the two steps of UV-imprinting, rib waveguides can be fabricated without an etching procedure. We demonstrated the proposed fabrication process by fabricating 2-μm-wide waveguides operating in single mode at 1310 nm. With TE-polarized light, the fabricated waveguides show an average transmission of 58.6% in a 30 mm long waveguide, corresponding to a loss of 2.3 dB.     

Fabrication of OH-free multimode fiber by vapor phase axial deposition

An ultimately OH-free multimode optical fiber was fabricated by vapor phase axial deposition (VAD). Dehydration conditions were investigated using a newly designed electric furnace. To exclude the OH ion contamination during a fiber-drawing process, simultaneous deposition of core and cladding was carried out. The loss mechanism for the fabricated OH-free fiber was analyzed. Transmission loss for this fiber approached the theoretically estimated value. The low-loss window, with less than 0.5 dB/km attenuation, ranged from 1.2 to 1.7 μm. Realization of the OH-free VAD fiber promises a very useful application in wavelength division multiplexing optical transmission systems, and widens the choice of wavelengths for optical sources.     

飞秒激光直写磁光玻璃波导研究

用飞秒激光在硼铝硅酸盐类磁光玻璃中直写光波导 。对比了 飞秒激光在TG20和TG28两种Tb³⁺浓度不同的硼铝硅酸盐玻璃中的磁光波导的效果 ,并研究 了飞秒激光脉冲的能量和偏振对波导的模式以及Verdet常数的影响。实验结果表明,圆偏振 光具有更低的 阈值能量,且诱导的折射率增量高于同功率的线偏振光,首次在实验上证明飞秒直写加工硼 铝硅酸盐磁光 玻璃时,折射率的改变主要源于离子键的三或四光子吸收过程。磁光系数测量表明, 飞秒激光的功 率与偏振对TG28中波导Verdet常数的影响较弱,Verdet常数损失量小于体材料的15%,而在TG20中 却可以达到70%。实验结果表明,TG28比TG20更适用于飞秒激光加工 磁光微结构,即通过对 磁光玻璃中掺杂离子浓度的选择,可以实现高磁光系数、高折射率调制的光学微结构的制备 。     

Fabrication of SiGe optical waveguides using VLSI processingtechniques

The fabrication of rib waveguides in SiGe using the local oxidation of silicon (LOCOS) was investigated. Samples consisted of strained Si_.97Ge_.03 or Si_.94Ge_.06 waveguiding layers with silicon cladding layers. The structural stability of these strained layers during thermal cycling up to 1050°C was examined using X-ray rocking curve analysis, scanning electron microscopy, and Nomarski microscopy of etched samples. Since single SiGe layers sufficiently thick to support optical waveguiding are typically above the equilibrium critical thickness, dislocation formation during high-temperature processing is unavoidable. This work concentrated on minimizing these dislocations. It was found that the dislocation density induced by the processing can be minimized by using a strain-compensating mask layer as a barrier to oxidation. For a specified thermal oxide layer thickness, higher oxidation temperatures were found to minimize the dislocation density relative to oxidation at temperatures closer to the metastable limit. Furthermore, the large birefringence found in all strained-layer SiGe waveguides is significantly reduced after LOGOS processing. These effects were used to fabricate the first reported optical waveguides and photonic devices in SiGe using standard VLSI-type processing. The device is a 1.3/1.55-μm duplexer with wavelength isolation of roughly 10 dB     

Fabrication of single-mode polymeric optical waveguides bylaser-beam writing

A laser-beam writing system is developed for large-area optical waveguide fabrication. Single-mode embedded channel optical waveguides are successfully fabricated on both 4- and 8-in silicon substrates using deuterated fluoromethacrylate polymers by laser-beam writing in photoresist and dry etching. The propagation loss of the waveguides is as low as 0.1 dB/cm at 1.3 μm     

Fabrication of ion-exchanged optical waveguides from dilute silver nitrate melts

Optical waveguides have been fabricated from silver nitrate melts diluted with sodium nitrate. Several important advantages are gained, including control over the surface refractive index value. On the basis of regular solution theory, the relationship between the surface index and the melt dilution is determined. Modification of the index profile with dilution, as predicted by interdiffusion theory, is discussed and the self-diffusion constant of silver ions in a typical soda-lime glass is measured.     

电场辅助离子交换制备玻璃光波导

使用电场辅助离子交换和热离子交换技术在玻璃基片上制作了平板波导。实验结果表明,这两种方法制作的波导的有效折射率分布不同,电场辅助离子交换技术制作的波导有效折射率呈近似阶跃型分布,而热离子交换制作的波导有效折射率分布为渐变型。经数值计算发现,近似阶跃型折射率分布的波导对光场限制得更好,更适用于制作有源光器件和集成光器件。     

Fabrication of planar dielectric waveguides with high optical damage threshold

We realized with a simple inexpensive process planar dielectric waveguides for the visible with the following improved properties: The waveguiding layers are mixed oxide films (∼40 percent TiO2in SiO2). They are hard and durable against mechanical and chemical attack. The losses are low and comparable to other planar waveguide materials. The films withstand high energy densities and intensities for pulsed and CW Laser irradiation, respectively.     

Fabrication of LiTaO3 optical waveguides by Ni diffusionbelow the Curie temperature

Using Ni diffusion into LiTaO₃ below the Curie temperature for the fabrication of optical waveguides was presented for the first lime. Ordinary and extraordinary polarization waveguide modes were obtained. The index distribution profiles of both modes were measured by a prism coupler. Loss in planar waveguides at 0.6328 μm is 0.7±0.1 dB/cm for the ordinary mode and 1.3±0.2 dB/cm for the extraordinary mode. Moreover, a Mach-Zehnder interferometer was fabricated by this method for electrooptic characterization. The measured half-wave voltage is 5.5 V and the extinction ratio is greater than 29 dB     

Loss measurements in stress-induced optical waveguides fabricated by an embossing process

Stress-induced light guides have been fabricated by an embossing process. The results of detailed loss measurements show that these waveguides can exhibit low optical attenuation.     

Fabrication of nanocrystalline silicon layers by plasma enhanced chemical vapor deposition from silicon tetrafluoride

Semiconductors - The data on fabrication of silicon layers on various substrates by plasma enhanced chemical vapor deposition from the (silicon tetrafluoride)-hydrogen system are reported. The...     

Fabrication and characterization of polymer optical waveguides with integrated micromirrors for three-dimensional board-level optical interconnects

This paper describes the fabrication and characterization of optical/electrical printed circuit boards (O/E-PCB) with embedded multimodal step index (MM-SI) waveguides and integrated out-of-plane micromirrors (IMMs) for three-dimensional (3-D) optical interconnects. Optical circuitry is built up on PCBs using UV lithography; 45/spl deg/ input/output (I/O) couplers are fabricated by inclined exposure. Commercial polymers are used as optical core and cladding materials. Critical mirror properties of angle, surface quality, reflectivity, and coupling efficiency are characterized experimentally and theoretically. Optical and scanning electron microscopy, white light interferometry, and fiber scanning method are used in the investigations. Sloping profiles measured as a function of the incident light showed the attainment of mirror angles of /spl alpha/=36/spl deg/-45/spl deg/ with /spl plusmn/2/spl deg/ consistency. Near-field optical imaging with a white light source showed that out-of-plane beam turning was achieved. Topography investigations revealed a rectilinear negative tapering shape regardless of the incoming beam angle or type of substrate. However, higher substrate reflectancy was observed to lower the mirror angle. The average propagation loss measured for 10-cm-long waveguides at /spl lambda/=850 nm by the cut-back method was 0.60 dB/cm; the excess loss calculated for the mirror coupling was 1.8-2.3 dB. The results showed that the IMMs can be incorporated in O/E-PCBs to couple light in and out of planar waveguides. Furthermore, the presented results indicate that optical waveguides with integrated micromirrors for optical 3-D wiring can be produced compatible with volume manufacturing techniques.     

有机聚合物光波导制作工艺综述

有机聚合物光波导光互连已成为实现短距离计算通信设计目标的最佳解决方法。短距离光互连是未来互连方向,综合性能优良的聚合物多模光波导是光互连中的重要组成部分。有机聚合物光波导的制作工艺对光波导的性能具有重要影响,故此对有机聚合物光波导的制作工艺进行了综述,并提出了一些未来的研发方向。     

涂覆法制作聚苯乙烯芯聚合物光纤工艺

阐述了溶液涂覆法生产苯乙烯（PS）芯聚合物光纤（POF）的工艺过程，其中皮材溶液可采用皮材和溶剂配制的方法制备，也可采用溶液聚合物的方法制备，POF皮层的形成可采用烘干和紫外固化工艺。并介绍了皮材单体的选择及溶剂，引发剂的浓度、聚合温度和氧气对皮材分子量及性能的影响。     

Surface and optical properties of silicon nitride deposited by inductively coupled plasma-chemical vapor deposition

The surface and optical properties of silicon nitride samples with different compositions were investigated.The samples were deposited on InP by inductively coupled plasma chemical vapor deposition using different NH3 flow rates.Atomic force microscopy measurements show that the surface roughness is increased for the samples with both low and high NH3 flow rates.By optimization,when the NH3 flow rate is 6 sccm,a smooth surface with RMS roughness of 0.74 nm over a 5 × 5μm2 area has been achieved.X-ray photoelectron spectroscopy measurements reveal the Si/N ratio of the samples as a function ofNH3 flow rate.It is found that amorphous silicon is dominant in the samples with low NH3 flow rates,which is also proved in Raman measurements.The bonding energies of the Si and N atoms have been extracted and analyzed.Results show that the bonding states of Si atoms transfer from Si0 to Si+4 as the NH3 flow rate increases.     

激光诱导化学气相淀积初始过程的研究

分析了激光诱导化学气相淀积过程中激光对气体的激发机理，采用半经典近似的方法，推导出气体吸系数的数学表达式，以此为基础讨论了实验参量－激光强度、频率、气体压强对气体吸收过程的影响。     

Fabrication process and optical properties of perdeuterated graded-index polymer optical fiber

We proposed a graded-index polymer optical fiber (GI-POF) enabling greater-than-gigabit data transmission in a short reach network by applying a two-step interfacial-gel polymerization process to a perdeuterated polymer material. Using this process, it is possible to fabricate a nearly optimum refractive-index profile with good reproducibility. In this paper, the preparation of a perdeuterated polymethyl methacrylate (PMMA-d8)-based GI-POF utilizing a PMMA cladding is described. This means that the low-loss PMMA-d8 material is used only for the core. Because the cladding transmits only a small fraction of the optical power, a low-loss material is not necessarily required for the cladding. It was verified that the low attenuation of the PMMA-d8 was maintained even if the cladding was composed of hydrogenated PMMA. As a result, a gigabit data transmission over 300 m was achieved by the PMMA-d8-core and PMMA-cladding GI-POF, which was impossible by the conventional PMMA-based GI-POF.