Proton exchange for high‐index waveguides in LiNbO3
TL;DR: In this article, the fabrication and characterization of optical waveguides formed in LiNbO3 by proton exchange in benzoic acid melts at 200-250°C is described.
Abstract: We describe the fabrication and characterization of optical waveguides formed in LiNbO3 by proton exchange in benzoic acid melts at 200–250 °C. Proton exchange, in LiNbO3 the replacement of lithium ions with protons, takes place when the substrate is immersed in the molten acid. We observe a surface increase in the refractive index of 0.12, for the extraordinary polarization only, with a step function index profile. This is the highest index increase obtainable to date for LiNbO3. Measured diffusion rates for x‐cut crystals are 1.37 μm2/h at T = 249 °C and 0.37 μm2/h at T = 217 °C, so that very deep guides can be formed in short times. Diffusion is somewhat slower in the z direction. The process as described is not useful for y‐cut crystals, since it damgaes this surface. Losses, measured on x‐cut samples, were <0.5 dB/cm. All measurements were made at 0.633 μm.
Citations
More filters
JDSU1
TL;DR: The lithium-niobate external-modulator technology meets the performance and reliability requirements of current 2.5-, 10-Gb/s digital communication systems, as well as CATV analog systems, and multiple high-speed modulation functions have been achieved in a single device.
Abstract: The current status of lithium-niobate external-modulator technology is reviewed with emphasis on design, fabrication, system requirements, performance, and reliability. The technology meets the performance and reliability requirements of current 2.5-, 10-, and 40-Gb/s digital communication systems, as well as CATV analog systems. The current trend in device topology is toward higher data rates and increased levels of integration. In particular, multiple high-speed modulation functions, such as 10-Gb/s return-to-zero pulse generation plus data modulation, have been achieved in a single device.
1,221 citations
Cites background from "Proton exchange for high‐index wave..."
...Proton exchange [8] is a low-temperature process (∼120 C–250 C) whereby Li ions from the LiNbO3 wafer are exchanged with protons from an acid bath....
[...]
TL;DR: The selected research activities on integrated optics components and devices using periodic structures are reviewed, with emphasis on the authors' works employing the electron-beam writing technique.
Abstract: The selected research activities on integrated optics components and devices using periodic structures are reviewed, with emphasis on the authors' works employing the electron-beam writing technique. The periodic structures include static gratings and dynamic ones produced through acoustooptic (AO) and electrooptic (EO) effects. They provide a variety of passive functions and effective means for guided-wave control. The review is made from the integration point of view, including the most recent results. First, the theoretical fundamentals are outlined and the electron-beam writing techniques, including the writing system, are discussed. Next, passive components (grating deflectors, filters, lenses, couplers, etc.) and elements for guided-wave controlling and detecting (AO and EO grating elements and photodetectors) are described. Then, integrated optic devices, i.e., wavelength demultiplexers, RF spectrum analyzers, optical disk pickup, etc., are presented. Finally, the possibility of future applications is discussed.
257 citations
TL;DR: Lithium Niobate microdisk resonators that feature optical quality factor ~10(5) are demonstrated using robust and scalable fabrication techniques, that operate over a wide wavelength range spanning visible and near infrared.
Abstract: Lithium Niobate (LN) is an important nonlinear optical material. Here we demonstrate LN microdisk resonators that feature optical quality factor ~105, realized using robust and scalable fabrication techniques, that operate over a wide wavelength range spanning visible and near infrared. Using our resonators, and leveraging LN’s large second order optical nonlinearity, we demonstrate on-chip second harmonic generation with a conversion efficiency of 0.109 W−1.
242 citations
TL;DR: In this article, a single-crystal fiber growth apparatus was designed and built using optical, mechanical, and electronic control systems that enable the growth of high optical quality singlecrystal fibers.
Abstract: We have designed and built a single‐crystal fiber growth apparatus. The apparatus employs novel optical, mechanical, and electronic control systems that enable the growth of high optical quality single‐crystal fibers. We have grown oriented single‐crystal fibers of four refractory oxide materials, Al2O3, Cr:Al2O3, Nd:YAG, and LiNbO3. These materials exhibit similar growth characteristics and yield fibers of comparable quality. Fibers as small as 20 μm in diameter and as long as 20 cm have been grown. Measured optical losses at 1.06 μm for a 10‐cm‐long, 170‐μm‐diam Cr:Al2O3 fiber were 0.074 dB/cm.
220 citations
TL;DR: Channel waveguides and Mach-Zehnder interferometers fabricated in LiNbO(3) by annealed proton exchange showed no variation in insertion loss or switching voltage was observed over 8 months for devices stored at room temperature.
Abstract: Channel waveguides and Mach–Zehnder interferometers were fabricated in LiNbO3 by annealed proton exchange. The waveguides had a loss of 0.15 dB/cm and a fiber-to-fiber insertion loss of 1.2 dB at 0.8 μm. The measured r33 electro-optic coefficient of the interferometers was 30 × 10−12 m/V ±5%, which agrees well with theory, indicating that there is no degradation in the r33 coefficient. No variation in insertion loss or switching voltage was observed over 8 months for devices stored at room temperature.
214 citations
References
More filters
TL;DR: The WKB approximation is used to derive simple equations that predict the shape of the index profile from measured mode indices of a planar optical waveguide and results are compared with mathematical solutions for exponential, Fermi, and step distributions.
Abstract: The WKB approximation is used to derive simple equations that predict the shape of the index profile from measured mode indices of a planar optical waveguide. This nondestructive test is a useful tool in the study of diffused guides. The index profile is assumed either to decrease monotonically from the surface or to be symmetrical in the case of a buried guide. The approximation uses straight line segments to connect the measured points. Results are compared with mathematical solutions for exponential, Fermi, and step distributions and with other independent experimental observations of the profile in a nickel-diffused LiNbO(3) guide.
566 citations
TL;DR: In this article, the first demonstration of phase matched waveguide electrooptic polarization conversion using a strip Ti-diffused lithium niobate waveguide and periodic electrodes was reported.
Abstract: We report the first demonstration of efficient phase‐matched waveguide electro‐optic polarization conversion Using a strip Ti‐diffused lithium niobate waveguide and periodic electrodes, we have achieved TE⇄TM conversion efficiency in excess of 99% with an applied voltage of 13 V The conversion efficiency is strongly wavelength selective; filter bandwidths between 45 and 15 A have been obtained
117 citations
TL;DR: In this article, the synthesis of HNbO 3 and HTaO 3 via ion exchange in hot aqueous acid solutions is reported, which is accompanied by a topotactic structural transformation from the rhombohedral LiNb O 3 structure to the cubic perovskite structure.
75 citations
TL;DR: In this article, optical losses of 6 dB/cm were measured for the highest-order mode; losses were higher for the lower-order modes, and an increase in the extraordinary refractive index at the surface of the plate due to silver exchange was estimated to be 0.12.
Abstract: Optical waveguides produced in LiNbO3 by immersing the x‐cut plates into molten AgNO3 are reported. An increase in the extraordinary refractive index of LiNbO3 at the surface of the plate due to silver exchange is estimated to be 0.12. In such a waveguide, optical losses of 6 dB/cm were measured for the highest‐order mode; losses were higher for the lower‐order modes.
59 citations
TL;DR: LiNbO3 and LiTaO3 have been found to undergo ion exhange in certain aqueous solutions and hydrate melts, replacing some or all of the lithium with hydrogen.
Abstract: LiNbO3 and LiTaO3 have been found to undergo ion exhange in certain aqueous solutions and hydrate melts, replacing some or all of the lithium with hydrogen. Complete exchange results in a structural transformation from the LiNbO3 to the cubic perovskite structure. Properties of the exchanged phases and some applications of this process to optical waveguide fabrication are discussed.
54 citations