Atomic spectroscopy and quantum optics in hollow‐core waveguides

Atomic spectroscopy is a well‐established, integral part of the physicist's toolbox with an extremely broad range of applications ranging from astronomy to single atom quantum optics. While highly desirable, miniaturization of atomic spectroscopy techniques on the chip scale was hampered by the apparent incompatibility of conventional solid‐state integrated optics and gaseous media. Here, the state of the art of atomic spectroscopy in hollow‐core optical waveguides is reviewed The two main approaches to confining light in low index atomic vapors are described: hollow‐core photonic crystal fiber (HC‐PCF) and planar antiresonant reflecting optical waveguides (ARROWs). Waveguide design, fabrication, and characterization are reviewed along with the current performance as compact atomic spectroscopy devices. The article specifically focuses on the realization of quantum interference effects in alkali atoms which may enable radically new optical devices based on low‐level nonlinear interactions on the single photon level for frequency standards and quantum communication systems.     

New waveguide modes in anisotropic structures

The existence of new hybrid waveguide modes of properly tailored integrated optical waveguides consisting of ultrathin films clad by positive birefringent media is pointed out.     

Cost of power—the user's perspective

Abstract

With the advent of fiber in the loop, transmission of power ceases to be through the traditional communications medium, and the objective of powering voice lines over fiber with the same reliability goals as plain old telephone service (POTS) raises several technological, regulatory, and business issues. In order to power the optical network unit (ONU) and provide backup power for it during commercial power outages, three strategies are identified: 1) providing loop powering from a ?48 volt CO/CEV power plant; 2) providing power and backup power locally, from or near the end of the loop in proximity to the OW; and 3) providing power from the curb or a power node. This paper constructs economic models to determine the worth of a watt at the 5-volt logic level at an ONU for each of the powering strategies. By normalizing all costs to the worth of a watt, comparisons can be made and appropriate architectures can be selected for various applications.     

领结形中空表面等离子体波导的传输特性

设计了一种领结形中空表面等离子体波导.采用频域有限差分法,对这种波导所支持的基模的能流密度分布、有效折射率、传播长度和模式面积随几何结构参数和工作波长的依赖关系进行了分析.结果表明,沿纵向的能流主要分布在两个上下突起所形成的中间区域.通过调整几何参数及工作波长,可以调节模式的有效折射率、传播长度和模式面积.在工作波长确定的条件下,有效折射率随突起半径的增大呈减小趋势,而传播长度和模式面积则随着突起半径的增大呈增大趋势,四个角上的圆弧半径对波导的传输特性有微调作用,左右扇形区域的半径对波导的传输特性有较明显 关键词： 集成光学 光波导 表面等离子体波导     

Propagation properties of a modified surface plasmonic waveguide with an arc slot

We introduce a modified surface plasmonic waveguide with an arc slot. The dependences of distribution of energy flux density, effective index, propagation length and mode area of the symmetric mode supported by this waveguide on geometrical parameters and working wavelength are analysed by using the finite-difference frequency-domain (FDFD) method. Results show that the energy flux density distributes mainly in four corners which are formed by two arcs, and the closer to the corners it is, the stronger the energy flux density will be. The effective index, the propagation length and the mode area are influenced by geometrical parameters, including the width, the thickness and the arc radius of the surface plasmonic waveguide, as well as the working wavelength. It has been shown that the surface plasmonic waveguide with an arc slot has better propagation properties than the surface plasmonic waveguide with a straight slot. This work may be helpful for applying the slot surface plasmonic waveguide to integrated photonics.     

弱导多层平面光波导辐射模的自由空间模近似

本文用自由空间模简化及近似表示弱导多层介质光波导的辐射模.只要辐射方向与介质界面的角度不是很小,近似程度很好.将其应用于求解光栅耦合器的辐射损耗问题,使计算公式简化,用自由空间模计算的结果与用辐射模计算的结果比较接近,也与其它近似方法进行了比较.     

Electro‐optic Polymer Ring Resonator Modulator on a Flat Silicon‐on‐Insulator

Optical polymers are a promising material of choice in the development of hybrid silicon photonics devices. Particularly, recent progress in electro‐optic (EO) active polymers has shown a strong Pockels effect. A ring resonator modulator is a vital building block for practical applications, such as signal processing, routing, and monitoring. However, the properties of the hybrid silicon and EO polymer ring modulators are still far from their theoretical limits. Here, we demonstrate a unique design of a hybrid ring resonator modulator simply located onto a silicon‐on‐insulator (SOI) substrate. Extra doping and etching of the SOI wafer is not required, even so we measured an in‐device electro‐optic coefficient r₃₃ = 129 pm/V. The ring modulator exhibited a high sensitivity of the electrically tunable resonance, which enabled a 3 dB bandwidth of up to 18 GHz. The proposed technique will enable efficient mass‐production of the micro‐footprint modulators and promote the development of integrated silicon photonics.     

基于MIM型表面等离子体光波导的Y形分束器的传输特性研究

采用二维时域有限差分(FDTD)法,分析并对比了弯曲分叉部分的形状分别为正弦形和圆弧形的基于金属-绝缘体-金属(MIM)型表面等离子体光波导的Y形分束器的反射率、传输率以及能量分束比随几何结构参数的变化关系。数值计算表明,波导宽度对这两种Y形分束器传输特性的影响较为明显,两个输出分支的偏移量和弯曲分叉部分的长度对这两种Y形分束器传输特性的影响比较微弱。在600～1500nm波长范围内,弯曲分叉部分为圆弧形的Y形分束器的传输特性比弯曲分叉部分为正弦形的好。对于非对称型Y形分束器,当弯曲分叉部分为正弦形时,偏移量对反射率、传输率和能量分束比的调节作用较为明显,能量分束比最大可达到2∶1。当弯曲分叉部分为圆弧形时,偏移量对反射率、传输率和能量分束比的调节作用较为微弱。     

Modified surface plasmonic waveguide formed by nanometric parallel lines

In this paper, two kinds of modified surface plasmonic waveguides formed by nanometric parallel lines are proposed. The finite-difference frequency-domain method is used to study propagation properties of the fundamental mode supported by these surface plasmonic waveguide structures. Results show that the transverse magnetic field of the fundamental mode is mainly distributed in the face to face region formed by two rods. With the same geometrical parameters and the same working wavelength of 632.8~nm, in the case of rods with a triangular cross-section, the degree of localization of field is strong, i.e. the mode area is small, but the fraction of the modal power in the metal increases, so the effective index increases and the propagation length of the mode decreases. With the same geometrical parameters, relative to the case of a working wavelength of 632.8~nm, when working wavelength is large, the mode area of transverse magnetic field distribution is large, i.e. the degree of localization of field is weak, and the interaction of field and silver is weak too, then the effective index decreases, so the propagation length increases. The rounded radii of rods have a great influence on the performance of the surface plasmonic waveguides with rounded triangular cross-sections, but have little influence on the performance of surface plasmonic waveguides with rounded square cross-sections. Since the distribution of transverse magnetic field, effective index, propagation length and the mode area can be adjusted by the geometrical parameters, this kind of modified surface plasmonic waveguide can be applied to the field of photonic device integration and sensors.     

有缓冲层的多层金属包层介质光波导的渐近展开方法

提出求解有缓冲层的多层金属包层介质光波导的一个准解析方法，它应用渐近开展理论将传播常数展开成一个小参数的级数，这一方法本身是精确的，它能达到任意所需的精度，然而四层和五层波导结构的数值计算实例表明，仅二阶近似解就足够精确了。这一方法的优点是简单并且不同层数波导结构以及ＴＥ和ＴＭ膜的解有相同的表达式形式。     

Phase conjugation of gap solitons: A numerical study

We study the effect of a nearby phase-conjugate mirror (PCM) on the gap soliton of a Kerr non-linear periodic structure. We show that phase conjugation of the gap soliton (in the sense of replication of the amplitude profile in the reverse direction) is possible under the condition of PCM reflectivity approaching unity. This is in contrast with the results for linear structures, where the wave profiles can be conjugated for arbitrary values of the PCM reflectivity. The sensitivity of the conjugation of the gap solitons to PCM reflectivity is ascribed to the fine balance of non-linearity with dispersion, necessary for their existence.     

Calculation of cutoff frequency of arbitrary weak guidance optical waveguides by extended boundary condition method

The extended boundary condition method is applied to both circular and elliptical regions for calculating cutoff frequencies V_c of weakly guiding optical waveguides, which consist of a uniform cladding and a core with arbitrary shape and index profile. The frequency shift formula method is explained by means of the extended boundary condition method on circular regions. Comparing the method with analytic and other rigorous methods, we show that it is indeed a powerful tool. Numerical results confirm that the mode designation and arrangement order in elliptical and rectangular waveguides are, in general, dependent on the aspect ratio.     

Design and optimisation of multimode 1d photonic band gap waveguide

The modal characteristics of planar waveguides with photonic band gap guiding properties are studied. It is demonstrated that a slight deviation from the periodicity in the photonic band gap multilayers can result in multimode transmission within the guiding layer. Possible applications of the results for avoiding single mode regime destruction due to fabrication process imperfection, as well as for designing such waveguides for conventional and emerging new applications of multimode photonic devices, are pointed out.     

Design and optimisation of multimode 1D photonic band gap waveguide

The modal characteristics of planar waveguides with photonic band gap guiding properties are studied. It is demonstrated that a slight deviation from the periodicity in the photonic band gap multilayers can result in multimode transmission within the guiding layer. Possible applications of the results for avoiding single mode regime destruction due to fabrication process imperfection, as well as for designing such waveguides for conventional and emerging new applications of multimode photonic devices, are pointed out.     

奇妙的空间光孤子

空间光孤子是当今非线性光学前沿的热点之一,在介绍稳态光孤子的形成机理之后,文章重点评述了空间光孤子奇特的相互作用行为以及它们在光控制光诸方面的应用前景。此外,文章还介绍了非相干光空间光孤子方面的最新动态。     

波前扰动产生空间暗光孤子及孤子演化的实验研究

报道实验上观测到用波前扰动的空间光暗孤子的产生及演化规律，实验测量表明，首先，产生的空间暗孤子的空间轮廓是双曲正割型的函数，这与逆散射理论上的空间暗孤子解是一致的其次，观测了空间暗光孤子在自散焦介质中的演化过程，实验结果与非线性薛定谔方程计算机数值模拟的结果是一致的，结果表明，空间暗光子随着光束传输过程逐渐演化并在演化过程中逐渐形成了多个孤子对；最后，测量了不同细丝宽度，非线性系数与光强子空间暗孤     

用迭代特征函数展开方法分析非线性平面介质波导

根据新近发展起来的迭代特征函数展开方法(IEEM),提供了一个分析任意非线性平板介质波导中TE波和TM波传播特性的途径。和有限元分析的结果比较,证明该方法在处理此类非线性问题时是非常有效的,而且很容易被推广到各种几何形状的非线性介质波导的分析中去。     

Integrated waveguide sensor utilizing organic photodiodes

We present a novel optical sensor platform, combining monolithically integrated ring‐like sensor waveguides together with ring‐shaped thin‐film organic photodiodes (OPDs) on one substrate. The OPDs serve as integrated light detectors, simplifying the detection system by minimizing the number of required optical components. The waveguide structures, including a means of coupling light in and out of the waveguides, serve as sensing elements. The functionality of the concept is demonstrated by an integrated carbon dioxide sensor, utilizing absorbance as sensing principle. The integrated optical sensor platform is suitable for the parallel detection of multiple parameters in a single sensor chip using sensor arrays. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Critical ray-like propagation modes along graded-index planar optical waveguides

Graded-index planar optical waveguides and surface compression layers were formed simultaneously in the surface layer of glass plates by ion exchange. A change in the refractometer patterns was observed. Before ion exchange, only a critical ray fringe was observed, but with ion exchange a guided wave fringe appeared on the high effective refractive index side of the ‘critical ray’ fringe, and the number of guided wave fringes increased. The guided wave fringe or fringes were birefringent, whereas the ‘critical ray’ fringe was kept nonbirefringent. It was concluded that the ‘critical ray’ propagated along the bottom of a waveguide, ie at the foot of the refractive index distribution.