基于光微流单模激光的液体折射率测量

Measurement of Liquid Refractive Index Based on Optofluidic Single Mode Laser

制备了高品质因子的法布里-珀罗(F-P)光学微腔,采用溶于液体的有机染料罗丹明6G(R6G)作为增益介质,实现了单模光微流激光的产生,激光的半峰全宽为0.260nm。在水的摩尔分数分别为1.09%,5.98%,11.91%,20.42%,30.75%,45.27%,51.89%的不同混合物溶剂(无水乙醇和去离子水)中实现了单模激光的产生,发现随着含水量的增加,中心波长向长波长方向移动,而当水的摩尔分数超过45.27%后,单模激光的中心波长开始向短波长方向移动。并根据单模激光波长的移动实现了混合溶液折射率的测量。测量结果及分析表明:最小可测量的折射率差值为6.31×10-4,测量灵敏度为411nm/RIU(RIU为单位折射率),并对测量的结果及误差进行了分析。

To achieve single-mode optical microfluidic laser,we prepare Fabry-Perot（F-P）optical microcavity with high quality factor and use the organic dye Rhodamine 6 G（R6 G）dissolved in liquid as gain medium.The full width at half maximum of laser output is 0.260 nm.In the following experiments,the generation of single-mode lasers in different mixed solutions（absolute ethanol and deionized water）with water molar fractions of 1.09%,5.98%,11.91%,20.42%,30.75%,45.27%,51.89%is achieved,respectively.It is found that the center wavelength of the single-mode laser moves toward long wavelength as water contents increasing.However,when the water molar fraction exceeds 45.27%,the center wavelength of the single-mode laser starts to move toward the short wavelength.Measurement of mixed solution refractive index is realized by single-mode laser wavelength movement.It is found that with the increase of water content,the measurement and analysis of the refractive index of the mixed solution show that the minimum measurable difference of refraction indexes is 6.31×10-4 and the measurement sensitivity is 411 nm/RIU,in which RIU is refractive index unit.The measured refractive index results and errors are analyzed.