Glass waveguides on silicon for hybrid optical packaging

Work on deposited glass waveguides on silicon to form waveguides and filters is reviewed. The choice of these particular waveguides makes sense only as part of a consistent approach to optoelectronic packaging. Hybrid optical packaging on silicon (HOPS) is described and briefly compared with other techniques. For these packages, two waveguides were developed: a tight mode waveguide with a silicon nitride rib core for matching a semiconductor laser and a loose mode waveguide with a phosphosilicate glass core for matching an optical fiber     

磁控射频溅射法制备光波导薄膜研究

采用磁控射频溅射法制备了用作光波导器件的玻璃薄膜。通过选取不同的溅射材料,在不同溅射条件下制备的玻璃薄膜的光学参数进行的测量、比较,并对其作为光波导的性能进行研究,通过理论上推导与计算,得出了在１,５５ｕｍ窗口下制备光波导器件的玻璃薄膜所应具备的溅射条件。     

Temperature dependence of sol-gel waveguides

The temperature dependence of the effective refractive index of waveguides based on sol-gel films is analyzed with allowance for the thermooptic coefficient of the waveguide materials and the expansion coefficient of the film material. The temperature dependence of the waveguide thermooptic coefficient on the film thickness is demonstrated. The parameters of the optical waveguides with a near-zero temperature coefficient are determined in a wide temperature range. Waveguides with a low temperature coefficient of about ?10^?5/°C in the temperature interval 20–80°C are designed.     

Optical amplification and photosensitivity in sol-gel basedwaveguides

The sol-gel process has emerged as an effective route for the fabrication of optical waveguides and guided wave devices and circuits. In particular, it is possible to incorporate active dopants like neodymium, erbium, and cesium for integrated optical active devices and circuits. A review of recent research on active devices and circuits based on sol-gel process is made. Specific studies undertaken in our laboratory on optical amplification and photosensitivity characteristics of sol-gel optical films are presented. In the case of modeling and analysis of active sol-gel films for the study of optical amplifiers, we present the atomic susceptibility theory of lasers and also the method of rate equations, duly taking into account the waveguide parameters. The beam propagation method is applied to study the propagation and gain characteristics of actively doped sol-gel film devices such as straight waveguide, Y-branch, and directional coupler. Formation of Bragg gratings in cerium-doped films are investigated. Also, futuristic applications in MEMS where the sol-gel process will be effectively used to form optical layers that can be controlled by mechanical effects are pointed out     

负胶-玻璃复合平面光波导传播特性的研究

本文报导了负胶-玻璃复合平面光波导传播特性的实验研究。测量并归纳了负胶介质薄层对银离子交换玻璃平面波导传播特性影响的实验趋势。介绍了弯曲条载波导的实验研究。     

激光直写法制备条形光波导中的功率密度阈值

采用溶胶-凝胶法(sol-gel)在Si基SiO2衬底上制备了SiO2-TiO2芯层薄膜,构成了以SiO2为下包层,空气为上包层的平面光波导。利用光纤激光器对平面波导的芯层进行直写,结合后续的化学腐蚀工艺得到了SiO2-TiO2条形光波导,并着重研究了激光直写波导过程中存在的功率密度阈值以及阈值随薄膜预热处理温度的变化关系。研究结果表明,激光直写SiO2-TiO2波导存在起始收缩阈值和烧蚀损伤阈值;随着薄膜热处理温度的提高,两个阈值同时增大,其中损伤阈值的增大趋势要大于收缩阈值;因而薄膜可承受的直写光斑直径变小,所得波导宽度显著减小。最后对直写制得条形光波导的导光性能作了测试分析,验证了波导的三维导光性。     

Ag膜电场辅助离子交换方法制作光波导

提出了银膜电场辅助离子交换方法制作光波导的理论,介绍银膜做电极与熔盐做电极制作光波导。对波导折射率进行分析,阐述了影响折射率的各种因素,最后给出了实验结果。     

Zero material dispersion in optical fibres

The material dispersion of optical fibres having cores of silica or phosphosilicate glass falls to zero at a wavelength between 1.2 and 1.3 ?m. A considerable increase in bandwidth can be obtained, especially with an l.e.d. source, by operation in this region.     

PLZT film waveguide Mach-Zehnder electrooptic modulator

We report the numerical analysis and the fabrication of a reversed-ridge PLZT film waveguide. It is single-mode, has low transmission loss, and has large transverse cross-section suitable for efficient coupling to single-mode optical fibers. We used this structure to fabricate Mach-Zehnder (MZ) waveguide modulators. The field distribution in the channel and Y branch waveguides was calculated using a beam propagation method to analyze the modal profiles and the propagation loss. The reversed-ridge waveguides and the MZ structures were fabricated on r-sapphire substrates with a patterned ITO spacer film by sol-gel deposition. At 1.55 μm the propagation loss was 2.7 dB/cm. In the MZ, the half-wave modulation voltage was 8.5 V using 1.55 μm light and electrode length of 3.5 mm     

Sol-gel glass waveguide and grating on silicon

This paper reports on the fabrication and characterization of hybrid organic-inorganic glass sol-gel slab and channel waveguides by ultraviolet light imprinting in thin films deposited by a one-step dip-coating process. The adjustment of chemical composition of the materials provides precise selection of refractive index from 1.48 to 1.52 at the wavelength of 632.8 mn. The refractive index of the waveguides at 1.55 μm is similar to that of optical fiber, thus reducing the reflection loss between the two to less than 0.01 dB. The effect of ultraviolet light exposure and heat treatment on waveguide refractive index is studied. Fabrication parameters to produce ridge waveguides are optimized to achieve very smooth side walls. Propagation losses in these waveguides are ~0.1 dB/cm. Single mode buried waveguides, at 1.55 μm wavelength, with circular mode profile are demonstrated     

Optical and structural properties of sol-gel derived nanostructured CeO2 film

Sol-gel derived nanostructured CeO2 film was deposited on glass substrate using by dip-coating technique with annealing at 65℃.X-ray diffraction (XRD),scanning electron microscopy (SEM),Fourier transform infrared (FTIR),UV/vis and photoluminescence (PL) spectroscopy studies were employed to analyze the structural and optical properties of the sol-gel derived nanostructured CeO2 film.The average crystallite size was estimated from the XRD pattern using by Scherrer equation as about 3-4nm.An SEM micrograph shows that the film was porous in nature and crack free.The UV-visible absorption spectroscopic measurement results showed that the products had conspicuous quantum size effects.The absorption spectrum indicates that the sol-gel derived nanostructured CeO2 film has a direct bandgap of 3.23 eV and the photoluminescence spectra of the film show a strong band at 378 nm:it may have a promising application as an optoelectronic material.     

Optoelectrochemical transduction on planar optical waveguides

Planar optical waveguides overlaid with electrochemically modulated sensing films constitute a powerful new class of chemical transducer. The effects on the modal absorption spectrum of depositing a highly absorbing electrochromic film on an optical waveguide are modeled. Theoretical and experimental results are given for such a device consisting of a lutetium biphthalocyanine film deposited on an indium tin oxide-coated potassium ion-exchanged glass waveguide, for application as a chlorine sensor     

High-purity germanium-sulphide glass for optoelectronic applications synthesised by chemical vapour deposition

Germanium-sulphide glass has been fabricated directly by chemical vapour deposition in the form of thin films on semiconductor substrates and as a bulk glass. Analysis shows a high-purity amorphous material, which has high potential for the fabrication of the chalcogenide optical waveguides and devices.     

多模掩埋式平面玻璃波导的制作及测试

利用加电场的离子交换和热处理等方法制作膜厚深的多模玻璃波导,并采用二步法制作了多模掩埋式平面玻璃波导,测试了m线谱,用White法计算了波导的折射率分布。     

Failure analysis of evaporated metal interconnections at contact windows

An analysis of the open metallization problem at oxide steps at the surface of planar devices is described. This failure mechanism is essentially based upon the presence of a film discontinuity which grows during the evaporation process at the interface of coarse and dense crystal structures of the evaporated film. The growth rate of the coarse surface is somewhat larger than that of the normal surface. This mismatch in growth rates gives rise to the film discontinuity due to the self-shadowing effect by the former surface. The film discontinuity is apt to occur at the sharp step of phosphosilicate glass because of the following two reasons: 1) a large vapor-incidence angle to the perpendicular side wall; 2) a spontaneous growth of the coarse surface at the sharp edge of the step. Techniques investigated to improve the interconnection reliability include : 1) evaporation at elevated substrate temperature (∼300°C), 2) reduction of the thickness of phosphosilicate glass, 3)perpendicular vapor incidence to the substrate, and 4) protection of the discontinuity against corrosive agents.     

Fabrication of Self-Organized Optical Waveguides in Photo-induced Refractive Index Variation Sol–Gel Materials With High-Index Contrast

Using photo-induced refractive index variation sol-gel materials, we fabricated a self-organized lightwave network (SOLNET), which is a concept of optical waveguides self-organized in photosensitive materials, whose refractive index increases by write beam exposure. The refractive index of the sol-gel materials increases from 1.65 to 1.85 when exposed to UV light/blue light and baking. When write beams with a wavelength of 405 nm are introduced into the sol-gel thin film under baking at 200degC, self-focusing is induced and a SOLNET is formed. In this study, we evaluated the light confinement effect and coupling efficiencies of the fabricated SOLNET. The half-width of the output beam spot decreases from 23.8 to 11.8 mum, and the coupling efficiencies increase as write beam intensity decreases from 1.0 to 0.1 mW. These results show that SOLNET widths become narrow when write beam intensity is reduced; thus, SOLNETs formed with a low write beam intensity produce a strong light confinement effect. Furthermore, during their formation, SOLNETs were found to be drawn toward reflective portions of the sol-gel thin film, such as defects or silver paste droplets, indicating that a reflective SOLNET is formed. We have shown that photo-induced refractive index variation sol-gel materials are promising materials for SOLNET fabrication. To create actual connections between nanoscale optical circuits, further work is necessary to optimize the baking temperature and write beam intensity required for nanoscale SOLNET formation.     

红外激光传输用聚苯乙烯—银—玻璃基体空心波导研究

利用液相镀膜法研制成了性能较好的传输用聚苯乙烯－银－玻璃基体小直径空心波导,波导长度达到1m左右,波导直径为800－1200μm,对于CO2激光（10.6μm）的传输损耗低达1.73dB/m,损伤阈值高于11.2W(17.2W/mm^2)。实验结果表明,聚苯乙烯－银－玻璃基体小直径空心波导适用于医学等领域CO2激光传输的要求,并有望在其他红外波段的激光能量传输中得到应用。     

Sol-gel processed silica/titania/ÿ-Glycidoxypropyltrimethoxysilane composite materials for photonic applications

Silica/titania/?-Glycidoxypropyltrimethoxysilane composite materials processed by the sol-gel technique were studied for photonic applications. Waveguide thin films with thickness more than 1.7 μm were prepared by the sol-gel spin coating technique and low temperature heat treatment from this high titanium content composite materials. The films were analyzed by atomic force microscopy (AFM), ellipsometry, differential thermal analysis (DTA), thermal gravimetric analysis (TGA), UV-visible spectroscopy (UV-VIS), and Fourier transform infrared (FT-IR) spectroscopy. It was observed that the film becomes thinner as the titanium contents increase. A change of the refractive index through the range 1.52–1.61 at the optical wavelength of 633 nm was achieved by varying the molar ratio between silica and titanium. A dense, low absorption, and high transparency in the visible range waveguide films could be obtained at a low temperature. It was also noted that organic compounds in the film would decompose in the temperature range from 200°C to 480°C. Accordingly, purely inorganic silica-titania films with a thickness of about 0.7 μm could also be obtained by a single-coating process, when the film was baked at a temperature of 500°C or higher. The waveguides properties and photonic applications of the composite material solgel films were also investigated.     

Cu离子交换过程对制备玻璃平面光波导特性的影响

用Cu离子交换技术,制备了soda-lime玻璃平面光波导。通过棱镜耦合技术测量了波导的有效折射率,用反WKB方法拟合得到了平面波导的折射率分布。研究发现,离子交换时间和温度2个可控的制备参数对制备的玻璃平面波导特性有较大影响,随着离子交换时间和温度的增加,波导的模式数和波导深度并非随之单调增加,波导模式数随着离子交换时间的增加先增加而后减小,而适当的离子交换时间可以使制备的波导具有最大的模式数和波导深度,且在该条件下增加离子交换温度可以提高Cu离子交换波导的蓝-绿发光强度,宽带发光中心波长在520 nm附近,发光强度取决于样品中Cu+的浓度以及Cu2+的影响。     

Planar optical waveguides prepared in GIL49 and BK7 glass substrates by K+-Na+ ion exchange with the electric field assistance

This report focuses on research into waveguides prepared by K⁺-Na⁺ ion exchange with the help of an electric field, and the subsequent comparison with waveguides prepared by pure thermal ion exchange. The goals of this work were to determine the characteristics of and to address the technological problems associated with waveguides prepared in two types of highly pure optical glass: special soda-lime silica GIL49 glass produced from pure raw materials and commercially prepared borosilicate BK7 glass. An appropriate chemical mixture, KNO₃:Ca(NO₃)₂ in the molar ratio of 41:59, was used as the source of potassium ions. Experiments were conducted at temperatures between 250 and 410°C, and electric field values between 0 and 150 V/mm. The number of modes, depth, profile, and the change in refractive index (Δn) were measured for samples from each type of glass under various technological conditions. All of these parameters can be controlled accurately and repeatedly by the electric field. These experiments have also shown that a particular advantage of these types of pure glass is the low waveguide optical losses (0.1 to 0.2 dB/cm) attainable.