Resonant grating waveguide structures
Resonant grating waveguide structures
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DOI：
10.1109/3.641320
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发表时间：
1997-11-01
影响因子：
2.5
通讯作者：
Friesem, AA
中科院分区：
文献类型：
--
作者：
Rosenblatt, D;Sharon, A;Friesem, AA
在一定条件下，波导光栅结构中会出现谐振现象。这种结构具有多层结构，其中最基本的结构包括衬底、薄介电层或半导体波导层以及其中蚀刻光栅的附加透明层。当用入射光束照射这种结构时，光束的一部分被直接透射，而一部分被衍射并随后被捕获在波导层中。一些被捕获的光然后向外再衍射，使得它与光束的透射部分相消干涉。在入射光束的特定波长和角度方向上，该结构“共振”;即，发生完全干涉并且没有光被透射。谐振的带宽基于诸如光栅深度和占空比以及波导层的厚度的参数。带宽可以被设计为非常窄（在0.1nm的量级上），这对于滤波器和开关应用是感兴趣的。这种谐振结构的制造利用常见的平面处理技术;薄膜沉积、蚀刻和亚微米光刻。本文回顾了以前的调查的共振现象，并提出了分析和数值模型，用于评估的结构和入射辐射的几何和光学参数的函数的共振。描述了用于制造这些结构的技术以及实验过程和结果，其中无源介质结构（Si_3 N_4-SiO_2）工作在0.56 μ m波长，半导体结构（InGaAsP-InP）工作在1.55 μ m波长，以及更复杂的有源（InGaAsP-InP）调制器结构。结果表明，该结构的光谱共振带宽为0.03 nm ~几nm，相应的精细度为300-15000，透射或反射时的共振强度与非共振强度之比可达100。该结构的调制频率可达10 MHz，并有可能达到更高的频率。结果表明，这种结构可以利用在光开关或调制器和窄带光谱滤波器的阵列，用于先进的光信号处理和通信系统。
Under certain conditions, a resonance phenomenon can occur in waveguide grating structures. Such structures have multilayer configuration, the most basic of which is comprised of a substrate, a thin dielectric layer or semiconductor waveguide layer, and an additional transparent layer in which a grating is etched. When such a structure is illuminated with an incident light beam, part of the beam is directly transmitted and part is diffracted and subsequently trapped in the waveguide layer. Some of the trapped light is then rediffracted outwards, so that it interferes destructively with the transmitted part of the light beam. At a specific wavelength and angular orientation of the incident beam, the structure ''resonates''; namely, complete interference occurs and no light is transmitted. The bandwidth of the resonance is based on parameters such as the grating depth and duty cycle, as well as the thickness of the waveguide layer, The bandwidth can be designed to be very narrow (on the order of 0.1 nm) which is of interest for filter and switch applications, The fabrication of such resonant structures utilizes common planar processing technologies; thin-film deposition, etching, and submicron photolithography. This paper reviews previous investigations on the resonance phenomena and presents analytic and numerical models for evaluating the resonance as a function of the geometric and optical parameters of the structures and incident radiation. The technologies for fabricating the structures are described and experimental procedures and results with passive dielectric structures (Si3N4-SiO2) operating at a wavelength of 0.56 mu m and semiconductor structures (InGaAsP-InP) operating at 1.55 mu m, as well as more complicated active (InGaAsP-InP) modulator structures. The results reveal that spectral resonance bandwidths can range from 0.03 nm to several nanometers, with corresponding finesses ranging from 300-15000, and that the ratio of resonant to nonresonant intensities in transmission or reflection can reach 100, The active structures were modulated at frequencies up to 10 MHz, with potential for reaching even higher frequencies. The results suggest that such structures can be exploited in arrays of optical switches or modulators and narrowband spectral filters, for use in advanced optical signal processing and communication systems.