Low-loss single-mode GaAs/AlGaAs miniature optical waveguides withstraight and bending structures

Low-loss single-mode GaAs/AlGaAs miniature optical waveguides fabricated for use in monolithically integrated optical circuits are discussed. The propagation characteristics of these waveguides with straight and S-bending structures have been investigated at wavelengths of 1.30 and 1.55 μm. The lowest propagation losses are estimated to be 0.58 dB/cm and 0.69 dB/cm at wavelengths of 1.30 and 1.55 μm, respectively. The total loss of an S-bending waveguide with a curvature radius of 2 mm and with a lateral displacement of 200 μm was 0.61 dB and 0.46 dB at wavelengths of 1.30 and 1.55 μm. The fabricated single-mode strip-loaded waveguides proved to be suitable for application of the semiconductor waveguide into monolithically integrated optical circuits     

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     

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     

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.     

MMI型1.31/1.55 μm GaAs波分复用/解复用器的研制

利用多模波导的自镜像原理,分析设计了一种能直接与单模光纤相耦合的具有最小循环比的1.31/1.55 μm波长的GaAs/GaAlAs波分复用/解复用器。该器件的输入、输出单模波导和SIE多模波导采用离散谱折射率法进行优化设计,最后获得了当输入、输出单模波导宽为3 μm、SIE多模波导宽度和最佳耦合长度分别为18 μm和5 602.8 μm时,该器件对1.31 μm和1.55 μm两个波长的隔离度均在70 dB以上,且传输损耗小于0.1 dB。     

Germanium-diffused waveguides in silicon for λ=1.3 μm andλ=1.55 μm with losses below 0.5 dB/cm

The authors present a simple technique for the fabrication of integrated optical channel waveguides that are prepared by indiffusion of an E-beam evaporated amorphous alloy of germanium and silicon into commercially available silicon with low dopant concentration, using only simple technological processes such as standard lithography, PVD, and diffusion. The waveguides are polarization independent and have waveguide losses as low as 0.3 dB/cm at wavelengths of λ=1.3 μm and λ=1.55 μm. The spot sizes are well suited for low-loss single-mode fiber device coupling, being on the order of a few microns in both horizontal and vertical directions     

Fabrication of submillimeter-radius optical waveguide bends withanisotropic and isotropic wet chemical etchants

Wet chemical etchants suitable for making GaAs/AlGaAs single-mode optical waveguide bends with radii as low as 300 μm for excess bend losses of 1 dB/90° and propagation losses as low as 1 dB/cm at λ=1.5 μm are described. Additional bend losses due to modal mismatch resulting from etchant anisotropy are investigated, and it is shown that in many cases such anisotropy does not limit bend performance     

Passive integrated-optical waveguide structures by Ge-diffusion insilicon

The realization of low loss optical channel waveguides and passive waveguide structures by a germanium indiffusion process into silicon will be discussed. Employing relatively simple technological processing like standard lithography, e-beam evaporation and diffusion, single-mode waveguides could be produced exhibiting polarization independent losses of as low as 0.3 dB/cm at wavelengths of λ=1.3 μm and λ=1.55 μm. S-bends fabricated with the same technology offered an excess loss of 1 dB at a radius of around 5 mm without any optimization. For a Y-junction designed with S-bends the maximum opening angle was determined to be 1.8° if an excess loss of 1 dB is allowed. The examination of directional couplers with various coupling lengths and distances revealed an excellent agreement between measurement and theory     

基于光子晶体多模波导的1．31／1．55μm双波长功分器的设计

设计了一种基于光子晶体多模波导的双波长光功分器,该器件能同时实现1.31 μm和1.55μm两种通信波长的光信号功率的平均分配,整个器件长度仅为15μm,是已报道的常规结构的182分之一.根据导模传输法,讨论了对称入射时光子晶体多模波导中的自映像效应,采用时域有限差分法模拟了光场在波导中的分布,入射场的单重像和二重像交替在波导中周期性地出现.并讨论了功分器的输出效率,及输出效率随位于单模波导与多模波导联结处的介电柱位置变化而产生的变化.     

Optical channel waveguide in chalcogenide (Ga:La:S) glass

A novel method for fabricating optical channel waveguides in Ga:La:S chalcogenide glass, through continuous wave direct UV laser writing (λ=244 nm) is reported. Well-formed single-mode channel structures, with low propagation losses of 0.38±0.05 dB/cm at 1.3 μm, were engineered using this technique     

Low-loss fluorinated poly(arylene ether sulfide) waveguides withhigh thermal stability

Some novel cross-linkable fluorinated poly(arylene ether sulfides) (FPAESI) were synthesized for use in optical waveguide applications. The materials have high thermal stability, high optical transparency in the infrared communication region, and much less birefringence than other thermally stable fluorinated polyimides. The refractive index of FPAESI after storage at 100°C for 1000 h remains almost constant, demonstrating their thermal stability. Furthermore, the refractive index of the material can be easily controlled by changing the fluorine content of the materials. The propagation loss of channel waveguides, which were fabricated using reactive ion etching was less than 0.42 dB/cm and 0.4 dB/cm at the wavelength of 1.55 μm for TE and TM polarizations, respectively     

Optical waveguides in SIMOX structures

Propagation characteristics determined experimentally and theoretically for planar optical waveguides formed in separation by implantation of oxygen (SIMOX) structures are discussed. All samples were found to support both TE and TM modes at both 1.15 μm and 1.523 μm with a lowest propagation loss of 8 dB/cm. This loss was measured at a wavelength of 1.15 μm for the TE₀ mode of a planar waveguide with a 2.0-μm-thick Si guiding layer     

Low-loss polyimide-Ta2O5-SiO2hybrid ARROW waveguides

A low-loss polyimide-Ta₂O₅-SiO₂ hybrid antiresonant reflecting optical waveguide (ARROW) is presented. The ARROW device was fabricated using both the organic and dielectric thin-film technologies. It consists of the fluorinated polyimide, tantalum pentoxide (Ta₂O₅), and silicon dioxide (SiO₂) hybrid layers deposited on a Si substrate. For transverse electric polarized light, the propagation loss of the waveguide as low as 0.4 dB/cm was obtained at 1.31 μm. The propagation loss for transverse magnetic polarized light is 1.5 dB/cm. An ARROW waveguide fabricated using the polyimide-Ta₂O₅ -polyimide material system is also presented for comparison     

Milled-groove method for fiber-to-waveguide couplers

We report a simple milled-groove process integrated with a two-step ion-diffused waveguide fabrication for efficient coupling between single-mode fibers and integrated optical waveguides andY- branches. We demonstrate such a coupling technique using a) a multimode transition to single-mode waveguide coupler, and b) an integrated optical 3-dB branching waveguide coupler from a single-mode fiber to silver/sodium ion-enchanged waveguide components. The coupling loss was about 1-2 dB over a propagation length of 2 cm at an operating wavelength of 633 nm.     

玻璃基片上双层多模光波导的制备

在光学玻璃基片上制作了双层掩埋式多模光波导芯片,这种芯片中的上、下两层光波导均通过熔盐离子交换和电场辅助离子迁移形成。对光波导的横截面以及输出光斑进行了观察,并进行了损耗和串扰测试。研究结果表明:双层多模光波导芯片中上、下两层光波导芯部横截面尺寸分别为29 m19 m和31 m20 m;两层波导的输出光斑尺寸相互匹配;两层波导传输损耗分别为1.000.32 dB/cm和0.780.35 dB/cm;两层光波导之间的串扰在17.7dB左右。这种玻璃基片上的双层多模光波导可以使板级光互连的互连密度增大一倍,提高EOCB的性能。     

Fabrication of polymeric large-core waveguides for opticalinterconnects using a rubber molding process

Polymeric large-core (47 μm×41 μm) optical waveguides for optical interconnects have been fabricated by using a rubber molding process. For low-cost low-loss large-core waveguides, our newly developed thick-photoresist patterning process is used for a master fabrication. Also a low-loss thermocurable polymer, perfluorocyclobutane (PFCB), is used in fabricating optical waveguides by rubber molding for the first time. The propagation loss is measured to be 0.4 dB/cm at the wavelength of 1.3 μm, and 0.7 dB/cm at the wavelength of 1.55 μm     

Low-loss substrate-removed (SURE) optical waveguides in GaAs-AlGaAsepitaxial layers embedded in organic polymers

Low-loss single-mode semiconductor rib optical waveguides fabricated in GaAs-AlGaAs epitaxial layers are removed from GaAs substrates and bonded to transfer substrates using a benzocyclobutene organic polymer. Optical quality facets were obtained by cleaving through the transfer substrate. An average propagation loss of 0.39 and 0.48 dB/cm at 1.55 μm wavelength for TE and TM polarizations, respectively, were measured. This was on average 0.05 dB/cm greater than control guides fabricated in GaAs-AlGaAs epilayers on GaAs substrates with air as the top cladding. This demonstrates the feasibility of a process enabling semiconductor polymer integration and processing both sides of an epitaxial layer     

A hybrid integrated waveguide isolator on a silica-based planarlightwave circuit

La and Ga substituted yttrium iron garnet single-mode buried channel waveguides, prepared using liquid-phase-epitaxial growth and Ar ion beam etching, have been successfully applied as 45° nonreciprocal waveguide rotators (NRWR) for hybrid integrated waveguide isolators at λ=1.55 μm. The optical and magneto-optical properties of the prepared 45° NRWRs and the epitaxial films are investigated in detail. We describe the assembly procedure and present optical measurement results for the hybrid integrated waveguide isolators. The hybrid isolators are composed of a 45° NRWR, a half-wave plate sheet, thin film-type polarizers, a thin plate-type permanent magnet and a silica-based waveguide on a silicon substrate. We obtained good waveguide isolators with low insertion losses (<3.2 dB) and high isolation (>25 dB) in the 1.5 μm wavelength band     

Fabrication and characteristics of low loss and single-mode channel waveguides based on DNA-HCTAC biopolymer material

A novel biopolymer, deoxyribonucleic acid-hexadecyltrimethylammonium chloride (DNA-HCTAC), is used as the core layer material in optical waveguide, and the cleanroom technology is successfully applied to fabricate the single-mode channel waveguides with low propagation loss. The prepared DNA-HCTAC material shows high optical quality at the optical telecommunication wavelengths, such as high transparency, relatively high refractive index and low birefringence. In the fabrication approach, polymethyl methacrylate (PMMA) is used as a barrier layer to protect the DNA-HCTAC material from the corrosive of photoresist developer, and the etching conditions are optimized to form the smooth wall and sharp cross-section of the waveguide. Lastly, the optical characteristics of DNA-HCTAC channel waveguides are measured. The results show that the DNA-HCTAC waveguide operates with single-mode propagation and has a low optical loss.     

Two-step purely thermal ion-exchange technique for single-modewaveguide devices in glass

Two-step purely thermal ion-exchange technique using two monovalent ions for single-mode waveguides is proposed. Experiments show embedded waveguide structure below the surface of the glass, as computer simulation predicted. The insertion loss of the straight waveguide was less than 1 dB for 19 mm long samples, at both λ=1.3 μm and 1.55 μm