SBIR Phase II: Low Cost On-Chip Photonic Crystal Slot Waveguide Absorption Spectrometer for Highly Sensitive, Continuous,In-Situ,Remote Specific Detection of Multiple VOC in Water

本小企业创新研究（SBIR）二期项目拟开发一种低成本封装近红外片上硅吸收光谱仪，用于同时特异检测水（地下水、废水和饮用水）中的多种挥发性有机化合物。在第一阶段，利用300微米长的光子晶体槽波导，在芯片上成功地通过近红外吸收特征检测了100 ppm水中的挥发性有机化合物二甲苯，在器件灵敏度和小型化方面取得了最好的结果。该器件将光子晶体波导中的慢光效应与光子晶体波导中心低折射率槽中高度集中的光场强度相结合。与传统波导相比，本文提出的光子晶体缝隙波导在相互作用长度上减少了1000倍，从而增强了光路中被分析物的光吸收。通过覆盖整个近红外波长范围的多个波导测量透射率，通过测量存在和不存在任何感兴趣的挥发性有机化合物分析物的透射率差异来确定吸光度。微型光谱仪将实现大规模平行鉴定和高通量分析。这项研究更广泛的影响是使地下水、饮用水和废水中多种挥发性有机化合物（VOCs）的连续、远程、原位监测和独特识别成为可能，具有高灵敏度和特异性，这是目前无法商业化的设施。集成的硅平台确保了大批量低成本生产。从商业角度来看，联合国环境规划署估计，到2020年，全球水市场将从目前的2500亿美元扩大到6600亿美元。所提出的光子晶体缝隙波导器件有望在该市场占据重要地位。所提出的通用技术的通用设计意味着可以在低成本的芯片实验室平台上实现原位分析物传感、检测和光谱学等多个领域，例如食品、空气、水质和健康的控制。通过连续、现场和远程监测，本研究开发的原型将消除目前工业水监测中存在的滞后时间，如河流和湖泊VOC监测有时会延长到几个月，从而实现对虚假泄漏和溢出的早期预警，而不是事后的损害控制和调解，从而增强环境和国家安全。

This Small Business Innovation Research (SBIR) Phase II project proposes to develop a low cost packaged near-infrared on-chip silicon absorption spectrometer for simultaneous and specific detection of multiple volatile organic compounds in water (ground water, waste water and drinking water). In phase I, the volatile organic compound xylene was successfully detected in water at 100 parts per billion through near-infrared absorption signatures, on chip with 300 micron long photonic crystal slot waveguides which represents the best results in device sensitivity and in miniaturization. The device combines slow light effect in photonic crystal waveguides with highly concentrated optical field intensity in a low index slot at the center of the photonic crystal waveguide. The photonic crystal slot waveguide proposed herein provides a factor of 1000 reduction in interaction length compared to conventional waveguides leading to enhanced optical absorption by analytes in the optical path. Transmission is measured from multiple waveguides covering the entire near-infrared wavelength range, and absorbance determined by measuring transmission differences in the presence and the absence of any volatile organic compound analytes ofinterest. The miniature spectrometer will enable massively parallel identification and high throughput analysis. The broader impacts of this research are the enabling of continuous, remote, in-situ monitoring and unique identification of multiple volatile organic compounds (VOCs) in groundwater, drinking water, and waste water, with high sensitivity and specificity, a facility that is not available commercially at present. The integrated siliconplatform ensures low cost production in high volume. From commercial standpoint, the United Nations Environment Program estimates the global water market to expand to $660 billion from the current $250 billion by 2020. The proposed photonic crystal slot waveguide device can be expected to occupy a significant position in this market. The generalized design of the proposed versatile technology implies possible implementation in multiple areas of in-situ analyte sensing, detection, and spectroscopy such as control of food, air, and water quality and health, in a lab-on-chip platform with low cost of ownership. Through continuous, in-situ and remote monitoring, the prototype developed from this research will eliminate the lag time that currently exists in industrial water monitoring, sometimes extending to few months as in VOC monitoring of rivers and lakes, thereby enabling early warning of spurious leaks and spills instead of after-the-fact damage control and mediation and thus enhance environmental and national security.