Lithium iodate planar waveguides by proton implantation

Permanent optical waveguides have been produced by proton implantation in LiIO₃ single crystals by using a Van De Graaff accelerator. The effects of the crystal cut and of the implantation paramaters on the optical waveguides properties, investigated by dark line mode spectroscopy, are presented. The profiles of the ordinary and extraordinary refractive indices are reconstructed by an inverse WKB method. Optical barriers with depths of few hundredths (Δn < 0) are currently obtained and their location can be accurately adjusted from 4 to 17 μm.     

Inhomogeneous broadening and alloy intermixing in low proton dose implanted InAs/GaAs self-assembled quantum dots

In this work, low-temperature photoluminescence (PL) and photoluminescence excitation (PLE) experiments have been carried out to investigate the optical and electronic properties of InAs/GaAs quantum dots (QDs) subjected to room-temperature proton implantation at various doses (5 × 10(10)-10(14)?ions?cm(-2)) and subsequent thermal annealing. The energy shift of the main QD emission band is found to increase with increasing implantation dose. Our measurements show clear evidence of an inhomogeneous In/Ga intermixing at low proton implantation doses (≤5 × 10(11)?ions?cm(-2)), giving rise to the coexistence of intermixed and non-intermixed QDs. For higher implantation doses, a decrease of both the PL linewidth and the intersublevel spacing energy have been found to occur, suggesting that the dot-size, dot-composition and dot-strain distributions evolve towards more uniform ones.     

Waveguiding properties in Yb:YAG crystals implanted with protons and carbon ions

We report the fabrication and analysis of optical waveguides in Yb:YAG crystals using either proton or carbon ion implantation. Planar waveguides were obtained by implanting the whole surface of the crystals. Channel waveguides were defined using an electroformed mask with apertures of 10, 15, and 20 micrometers in width. The waveguiding properties of the structures were analyzed, showing good light confinement based on the transversal mode distribution and optical transmission measurements. The spectroscopic properties of the Yb ions in the YAG host are preserved after the implantation process, which demonstrates the potential of this technique for tailoring microcomponents for integrated optics applications. In particular, the Yb:YAG waveguides have the potential to operate as miniature lasers.     

质子注入对二硫化钼/聚芳醚砜复合材料摩擦学行为的影响

研究了质子注入对二硫化钼/ 聚芳醚砜(MoS₂ / PES-C) 复合材料摩擦学行为的影响, 并用红外光谱和X射线光电子能谱研究了质子注入引起的复合材料结构变化。结果表明, 质子注入导致MoS₂ / PES-C 复合材料中基体PES-C 的部分降解, 并最终在复合材料表面层形成一种富碳结构, 质子注入过程中填料MoS₂ 没有发生明显的化学变化。摩擦磨损实验表明, 质子注入能够提高其耐磨性, 尤其剂量达到1. 25 ×1016 ions/ cm2 时, 其摩擦系数和磨损率同时降低。磨损机理分析表明, 质子注入后复合材料的磨损机理从未注入质子的粘着磨损和塑性变形转变为疲劳磨损。      

GaAs/AIGaAs laser arrays with and without proton isolation

Abstract

Two types of GaAs/AIGaAs laser arrays, each consisting of five emitters and suitable for high power operations, have been fabricated and tested. They are easily fabricated, have high yield and deliver high power. The first array structure was fabricated using proton implantation to define the active lasing channels. Damage introduced by proton bombardment provides both electrical and optical confinement for the lasing channels. We have investigated the effect of heat treatment on the performance of these lasers and have found that the heat treated samples had a lower threshold current and higher quantum efficiency. For 400 μm long devices, with uncoated facets, we have measured a threshold current of 200 mA and a peak power of 231 mW/facet. The highest external quantum efficiency is 60%. We have also fabricated laser arrays with a simple, self‐aligned, index guided ridge waveguide structures. We have obtain a pulsed output power of up to 551 mW/facet with a quantum efficiency of 37.4%. The typical threshold current is 370 mA.     

质子、电子综合辐照作用下Teflon FEP/Al辐照损伤效应研究

在地面模拟研究了能量为30keV的质子与电子辐照对Teflon FEP/Al的光学性能退化的综合影响。结果表明,质子辐照引起Teflon FEP/Al在可见光区反射性能退化,而电子引起其在可见光与近红外区反射性能的全面下降。电子辐照更多的是使材料的大分子形成激发态进而轰击出主链上的F原子,形成自由基以及游离态的C。质子辐照时,除产生上述的辐照缺陷外,H~*的离子注入还使材料中形成各种新的官能团。质子与电子辐照的顺序不同,Teflon FEP/Al的C_(1s)谱也明显不同。     

Planar waveguide in beta barium borate formed by proton implantation and optical properties in visible and near-infrared band

β-BaB₂O₄ is nonlinear crystal that provides attractive features for various nonlinear optical application. We report on z-cut β-BaB₂O₄ planar waveguide produced by multi-energy proton implantation in total of 3 × 10¹⁶ ion/cm² at room temperature. The refractive index profile is a barrier-confined distribution, which is reconstructed according to the dark mode spectroscopy at the wavelength of 633 nm. The near-field light intensity profiles in the visible (633 nm) and near-infrared band are measured by end-face coupling method. The absorption spectra recorded over the wavelength range 185–2500 nm shows there is hardly change after proton implantation. The investigation results of the Raman spectra demonstrate that the positions and widths of all the peaks are very similar in the β-BaB₂O₄ crystal and waveguide layer.     

羧酸吡啶类氢键液晶分子的合成及表征

以4-己氧基苯甲酸为质子给体,4-硝基苯乙烯基吡啶为受体,四氢呋喃为溶剂,制备了一种液晶超分子复合物—羧酸吡啶类氢键自主装型液晶复合物,用DSC和热台偏光显微镜对所合成化合物进行了相态和液晶性研究,并用IR1、H-NMR对所合成化合物进行了结构表征。结果表明:合成了目标化合物;IR结果证明了羧基和吡啶环间分子间氢键代替了羧基间的分子间氢键;相态及液晶行为研究证明了氢键复合物具有典型的热致液晶性能且呈现明显的向列型液晶态。     

Absorption enhancement of near infrared in Te doped nanoporous silicon

In this paper, the optical properties of Te doped nanoporous silicon have been studied. The nanoporous silicon was fabricated by using alkaline etching and electrochemical anodization. The etched nanoporous silicon was injected with Te atoms by ion implantation. These nanostructures formed in electrochemical anodization directly affect the optical properties of nanoporous silicon such as reflectance, transmittance and absorptance. According to the optical measurement, the absorptance of the Te doped nanoporous silicon is over 80 % in the wavelength range from 250 to 1,100 nm. The absorptance of Te doped nanoporous silicon at wavelength longer than 1,100 nm is almost four times of that of untreated silicon, indicating that the ion implantation of Te element increases the NIR absorption of nanoporous silicon considerably.     

Degradation in optical reflectance of Al film mirror induced by proton irradiation

Mirror made of Al films can yield high reflectance over a broad wavelength range, and have been widely used in spacecraft optical instruments for high quality optical applications. However, such mirrors might be deteriorated under the irradiation of charged particles in the Earth radiation belt. In order to reveal the deterioration mechanism, the change in optical properties of Al film mirrors induced by proton irradiation with less than 200 keV was studied in a vacuum environment with a heat sink. Experimental results showed that the proton irradiation led to an obvious degradation of spectral reflectance of the Al film mirror within the wavelength range from 250 to 800 nm. The threshold fluence 1 × 10¹⁶ cm⁻² was found, above which the reflectance decreased greatly with increasing proton fluence when the radiation damage primarily occurred in the Al film. According to the experimental results, a formula for the performance evolution of Al film optical mirrors irradiated with protons is proposed.     

Fabrication of ridge waveguide on the ion-implanted TGG crystal by femtosecond laser ablation

The ridge waveguide on the TGG crystal has been fabricated through the combination of the ion implantation and the femtosecond laser ablation. Firstly, optical planar waveguide was formed on the top surface of TGG crystal by ion implantation. To investigate the damage induced by the 6.0?MeV Si ion implantation at a dose of 2.0 × 10¹⁵ ions/cm², the vacancy distribution was obtained by the SRIM simulation programme. Subsequently, the ridge waveguide with a width of 20?µm was produced by femtosecond laser ablation. The optical guiding properties of the ridge TGG waveguide were measured at the near-infrared wavelength (976?nm) by the end-face coupling technique. The work demonstrated that the manufactured waveguide structure possesses the ability to confine the light into guided mode, making it potentially valuable in integrated devices.     

Refractive indices and thicknesses of optical waveguides fabricated by silicon ion implantation into silica glass

Planar optical waveguides formed by Si ion implantation into PECVD SiO₂ have been characterized by the dark mode spectroscopy method at a wavelength of 0.6328 μm. The measured effective index values of the guided modes have been used to investigate the optical properties of the core layers of the waveguides after different pre-implantation treatments. It was found that annealing the specimens before implantation, affected both the refractive index and thickness of the core layers. In the annealed specimens a thicker core layer and a larger relative refractive index difference between the core and the buffer layer resulted.     

入射质子能量对银膜反射镜光学性能的影响

为探讨空间高能质子模拟试验方法,用基于蒙特卡罗方法的SRIM程序计算了质子在石英玻璃基银膜反射镜中的射程和能量损失分布,试验研究了不同能量质子辐照对反射镜光学性能的影响.能量低于160keV时,50%以上的质子能量损失在表面膜中,随着能量的增大,质子在膜系中的能量损失逐渐减小;在1016/cm2注量条件下,100keV质子辐照引起350～500nm波段反射率明显下降,而0.5MeV和1MeV质子辐照对光谱的影响很小;计算与试验结果表明,低能质子辐照对反射镜的膜系损伤起主要作用,在进行空间质子辐照模拟试验时,能量选取应低于200keV.     

Application of ion implantation for synthesis of copper nanoparticles in a zinc oxide matrix for obtaining new nonlinear optical materials

We have obtained a layered composite material by implantation of single crystal zinc oxide (ZnO) substrates with 160-keV Cu⁺ ions to a dose of 10¹⁶ or 10¹⁷ cm⁻². The composite was studied by linear optical absorption spectroscopy; the nonlinear optical characteristics were determined by means of Z-scanning at a laser radiation wavelength of 532 nm. The appearance of the optical plasmon resonance bands in the spectra indicated that ion implantation to the higher dose provides for the formation of copper nanoparticles in a subsurface layer of ZnO. The new nonlinear optical material comprising metal nanoparticles in a ZnO matrix exhibits the phenomenon of self-defocusing and possesses a high nonlinear absorption coefficient (β=2.07×10⁻³ cm/W).     

Critical currents and dissipative effects in proton-irradiated ceramic YBCO and BISCO

Transport properties in pellets of YBCO and BISCO are studied before and after 6.5-MeV proton implantation. The average critical current was strongly enhanced but in one case also weakened, probably due to the unfavorable interaction with the pre-irradiation defect structure. Characteristic parameters are compared and discussed.     

Influence of 250 keV Ge ions fluence on electrical and optical properties of SiC

Commercially graded SiC samples were implanted with 250 keV germanium ions (Ge⁺) at room temperature. For Ge⁺ ions source, laser-induced plasma (LIP) technique was used. Ge⁺ implantation was confirmed by energy dispersive X-ray (EDX) analysis. Change in FWHM and lattice constant of SiC samples has been observed after the Ge implantation, calculated by Bragg's law from XRD analysis. A comparison of the electrical and optical properties of SiC before and after Ge⁺ implantation (SiC:Ge) has also been made. Electrical diagnostic comprises of a four-probe method for the measurement of resistivity whereas Raman spectroscopy is employed for the optical investigation. Resistivity measurements of SiC and SiC:Ge samples showed that resistivity decreases as Ge⁺ implantation increases. Raman spectroscopy of the SiC and SiC:Ge showed that Raman band became broadened and is shifted towards the lower wave number with the increase in Ge ion fluence. The increase in Ge ions fluence enhances the lattice defects which are responsible for broadening in XRD and Raman peaks as well as increase in conductivity of the samples.     

低能离子注入对聚苯胺薄膜的改性研究

利用低能量的N 对电化学合成的聚苯胺薄膜进行了离子注入改性 ,实验结果表明 :聚苯胺薄膜经N 注入后薄膜电导率随注入能量和剂量的增加而提高 ,电导率最大提高了 9个数量级 ,即由本征态的电导率 (>1× 1 0 -12 S/cm)提高到 1 76× 1 0 -3 S/cm(注入剂量 :3× 1 0 17ions/cm2 ,注入能量 :35keV) ;同时离子注入后聚苯胺薄膜在可见光范围的吸收比增强。     

The importance of orientation in proton transport of a polymer film based on an oriented self-organized columnar liquid-crystalline polyether

We prepared membranes based on a liquid-crystalline side-chain polyether obtained by chemical modification of commercial poly(epichlorohydrin) (PECH) with dendrons. This polymer exhibited a columnar structure, which could form an ion channel in the inner part. The columns were successfully oriented by taking advantage of surface interactions between the polymer and hydrophilic substrates, as confirmed by X-ray diffraction analysis (XRD), environmental scanning electron microscopy (ESEM) and optical microscopy between crossed polars (POM). Column orientation was found to be crucial for effective transport: the oriented membranes exhibited proton transport comparable to that of Nafion® N117 and no water uptake. An increase in sodium ion concentration in the feed phase suggested a proton/cation antiport. On the contrary, no proton transport was detected on unoriented membranes based on the same liquid-crystalline side-chain polyether or on unmodified PECH.     

Optical properties of Cu and Ag nanoparticles synthesized in glass by ion implantation

Metal nanoparticles synthesized by sequentially ion-implanted Ag and Cu into silica glasses have been studied. The implantation doses (×10¹⁶ ions/cm²) were 5Ag, 5Cu and 5Ag/5Cu, respectively. The optical and microstructural properties of the nanoparticles were characterized by optical absorption spectra and transmission electron microscopy (TEM), respectively. Fast nonlinear optical refraction and nonlinear optical absorption coefficients were measured at 1064 nm of wavelength using Z-scan technique. Results in this paper indicate that the nonlinear refractive index for the Ag/Cu implanted system has a higher value compared to single Ag or Cu implantation nanoparticles.     

Planar optical waveguides obtained in Z-cut LiNbO3 and LiTaO3 by proton exchange in LiHSO4 vapors

A new proton source – LiHSO₄ vapors at low temperature – was used in forming optical waveguides in LiNbO₃ and LiTaO₃. The proton-exchanged layers were investigated by mode spectroscopy and infrared absorption spectroscopy. An estimate of the optical losses and phase contents of the waveguides was made. The diffusion parameters were determined for both types of crystal, and were compared to those obtained when benzoic acid melt was used as a proton source. The results presented could contribute to the realization of waveguides with controled phase compositions. The method proposed allows the use of a very simple and safe chamber construction, and the production of low-loss waveguides in a single technological step.