退火质子交换法制作LiNbO_3光波导

文章介绍了退火质子交换机理和制作LiNbO3光波导的工艺过程。     

焦磷酸质子交换LiNbO_3光波导制备技术研究

采用焦磷酸质子交换技术制备 ＬｉＮｂＯ３光波导,总结了交换条件、退火工艺和波导特性的实验结果,报告了表面腐蚀情况和单模条件。测量分析了退火前后波导折射率分布的变化,采用循环迭代法拟合折射率分布。结果显示退火前后的折射率分别呈近似阶梯和近似指数的分布,均可用费米函数良好地描述。     

Ti:LiNbO_3波导中的电光-光致折射调制

本文演示一种Ti内扩散LiNbO_3波导中以光致折射和电光效应的组合为基础的简单而廉价的调制器。     

Ti:LiNbO_3波导相位调制器实验研究

本文全面介绍Ti:LiNbO_3波导相位调制器的主要设计参数,详细阐述相位调制器有关性能的测量方法,并扼要说明波导制作和测试结果。试验研究实现了光纤对波导的耦合,并用金属壳体封装。试验测量光纤-波导-光纤插入损耗3.8dB,半波电压7V,调制深度83%     

Ti:LiNbO_3波导与光纤耦合综述

本文从Ti:LiNbO_3波导与光纤的模场分布、数值孔径以及几何尺寸三要素论述Ti:LiNbO_3波导与光纤的耦合问题,并扼要介绍几种适合工程应用的高效耦合方法.     

质子交换LiNbO_3波导中声光共线相互作用的实验研究

本文报导了对质子交换LiNbO_3波导中声光共线相互作用的实验研究,给出了在这样相互作用下光导模向基板辐射模转换的效率与声表面波功率的关系以及衍射光束的空间分辨率。     

质子交换LiNbO3光波导路和Ti扩散LiNbO3光波导的光感应折射率变化的比较

Ti扩散LiNbO3光波导和质子交换光波导路是以各种光器件制作为基础制成的光波导路。不过，在这些光波导路中，特别是在短波长区域，发生折射率随光的入射而变化的光感应折射率变化，这是其实用化的最大障碍。本文测定了上述两个光波导路的光感应     

退火质子交换法制作LiNnO3光波导

文章介绍了退火质子交换机理和制作光波导的工艺过程。     

质子交换LiTaO3平板光波导的表征

本文采用质子交换法制备了Ｚ切ＬｉＴａＯ３晶体平板光波导，并研究了退火前后波导的光学性能。讨论并用实验结果验证了退火前后波导内折射率的分布，实验证明退火前波导层的折射率分布为阶跃型，退火后其分布为费米型。在６３２．８ｎｍ的Ｈｅ－Ｎｅ激光波长下的测量结果表明：质子交换ＬｉＴＡＯ３波导层折射率增量退火前约为０．０１２，退火后为０．０２５。     

Theoretical modeling of optical amplification in Er-doped Ti:LiNbO3 waveguides

An accurate theoretical analysis is presented describing optical amplification in Er-diffused Ti:LiNbO₃ channel waveguides. It follows as far as possible the theory already developed for Er-doped fibers. As optical pumping around λ_p≈1.48 μm is considered, a quasi-two-level model for the Er³⁺ ions is used with wavelength-dependent cross sections. The optical gain in the 1.53 μm<λ<1.64-μm wavelength range is evaluated. The characteristic parameters, as Er concentration profile, cross sections, pump, and signal mode distributions and waveguide (scattering) losses are taken from experiments. Examples of numerically calculated pump-, small-signal-gain-, and ASE-evolutions are presented. The model has been tested by comparing computed and experimentally observed gain characteristics for Xˆ- and Yˆ-cut LiNbO₃; an almost quantitative agreement has been obtained     

Fabrication tolerance of Ti:LiNbO3 waveguides

A simulation program based on the three-dimensional beam propagation method (BPM) is used to study the fabrication conditions of single-mode Ti:LiNbO₃ waveguides. The calculated cutoff wavelengths are in good agreement with experimental data. The thickness of titanium needed to support the fundamental and first-order modes for three Ti strip widths (6, 7, and 8 μm) is calculated. The two-dimensional BPM is used to calculate the coupling length from the fabrication conditions. Results are consistent with measured data. The fabrication tolerances of the coupling length of directional couplers are also presented     

Proton-exchanged optical waveguides in Z-cut LiNbO3 using phosphoric acid

Proton-exchanged Z-cut LiNbO₃ planar waveguides formed using phosphoric acid were characterized optically. The refractive index profile and the diffusion parameters were studied systematically. These waveguides have propagation losses of less than 1 dB/cm and exhibit properties that are different from those obtained using benzoic acid. The index profile is not a simple step function and can be modeled accurately by a polynomial expression. A maximum surface index increase of 0.145 was measured at a 0.633-μm wavelength. The diffusion constant D₀ and the activation energy Q for the proton-exchange process using this acid were found to be 6.43×10⁸ μm²/h and 82.91 kJ/mol, respectively. The annealing properties of these waveguides were also established, and the effects of annealing on surface index change and waveguide depth increase were found to follow a power-law relationship     

Millimeter-wave Ti:LiNbO3 optical modulators

The design, fabrication, and characteristics of ridged Ti:LiNbO ₃ optical modulators that work in the millimeter-wave region are presented. A new concept of design under velocity matching is demonstrated for the proposed modulator. It has been shown by calculation that impedance matching is achieved and conductor loss is greatly reduced under velocity matching with wider gaps and a thicker coplanar waveguide electrode in conjunction with a ridge structure. Two types of Mach-Zehnder optical intensity modulators for the wavelength of 1.5 μm are developed. A fully packaged module for 40 Gb/s transmission with a half-wave voltage of 3.5 V and a broadband modulator responsible up to 100 GHz with a half-wave voltage of 5.1 V     

Ti扩散LiNbO_3单模波导参数的测量

对Ti扩散LiNbO_3波导分别采用双曲正割和抛物线分布来近似其折射率的高斯分布,在两个波长下由相应的两种近似本征值方程分别推得了单模波导参数的计算公式,并在4880(?)和6328(?)激光波长下利用棱镜耦合器测量了单模波导参数,对测量结果给出必要的理论分析。     

Cutoff wavelength of periodically segmented waveguides in Ti:LiNbO3

The cutoff wavelength for Ti:LiNbO₃ periodic segmented waveguides (PSWs) with different duty-cycles and of continuous waveguides has been measured for both polarizations, PSWs are described by an equivalent continuous waveguide and, using this model, a universal relationship between the cutoff wavelength of PSWs with different duty-cycles is proposed and verified experimentally     

Integrated optical Ti:Er:LiNbO3 soliton source

Efficient diode-pumped and harmonically mode-locked operation of a fully packaged Ti:Er:LiNbO₃ waveguide laser at 1562- (TE) and 1575-nm (TM) wavelength has been demonstrated. The mode-locked pulses have been characterized in terms of time-bandwidth product, fine tuning, and stability. Noise suppression of 42 dB at the relaxation oscillation frequency has been achieved by feedback-controlled pumping. An external amplitude modulator has been used for encoding of the mode-locked pulse train with different bit sequences. Bit error rates of 10^-10 for a 1-0-1-0-bit sequence has been observed for more than half an hour     

LiNbO3 optical waveguides formed in a new proton source

Proton-exchanged planar waveguides have been fabricated on Z-cut and X-cut lithium niobate crystals by using a new proton source formed by a mixture of benzoic and adipic acids. Waveguide index profiles and optical characteristics have been obtained at different values of the adipic-benzoic acid concentration ratio. The samples have been structurally characterized by Raman and infrared (IR) absorption spectroscopy and double-crystal X-ray diffraction. Good quality samples have been fabricated by using 30 mol% ratio dilution, showing very low scattering levels (<0.1 dB/cm), relatively high electrooptic coefficient (r₃₃=0.88 pm/V), and low relative percentage of interstitial protons (26%). The main factor limiting the waveguide optical properties is the substitutional-interstitial proton ratio, which can be easily controlled to produce good quality waveguides. A demonstration of the repeatability of the exchange process in the acid mixture is also provided     

Design parameters of Ti:LiNbO3 waveguides for optimumacoustooptic interaction efficiency

A computer model of optical and surface acoustic wave modes in titanium indiffused Y-cut LiNbO₃ guiding structures is used to produce several graphs for the design of guided-wave acoustooptic devices with optimum interaction characteristics. The design concentrates on waveguide fabrication parameters in order to achieve the optimum acoustic frequency and the acoustooptic interaction bandwidth. The optimum acoustic frequency for a given value of Ti film thickness and diffusion depth is defined as the frequency causing the maximum value of the overlap integral     

A broadband Ti:LiNbO3 optical modulator with a ridgestructure

We describe the design, fabrication, and characteristics of a Ti:LiNbO₃ optical modulator with a ridge structure. The structure keeps microwave propagation loss low and enables a large interaction between microwaves and optical waves under the conditions of velocity-matching and impedance matching, resulting in a large modulation bandwidth and low driving voltage. Using this structure, we have developed an optical intensity modulator with an optical 3-dB bandwidth of 75 GHz and a driving voltage of 5.0 V at a wavelength of 1.5 μm