Chinese Optics Letters, Vol. 17, Issue 11, 110601 (2019)
Hollow-core fiber-based Raman probe extension kit for in situ and sensitive ultramicro-analysis
Hao Cai1, Xingtao Yu1, Qian Chu1, Zhiqiang Jin1, Bo Lin2, and Guanghui Wang1,*
- 1College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- 2China Academy of Electronics and Information Technology, Beijing 100041, China
A metal-lined hollow-core fiber-based Raman probe extension kit is proposed in this Letter for in situ and sensitive ultramicro-analysis. A hollow-core fiber can confine light and fluid samples in its hollow core, with enhanced light–sample interaction. By using a homemade light coupling device with a glass window for liquid isolation, a 3.5-cm-long hollow-core fiber could mount on and connect to a Raman probe, with perfect light coupling efficiency. After full filling the hollow-core fiber chamber with a volume of 13 μL by using a syringe pump, it can act as an extension kit for an ordinary Raman probe and be used as a ultramicro-analysis tool for the sample of microfluidic chips. In order to enhance its sensitivity, a gold film coated fiber tip is inserted into the capillary, which can double the Raman signal received by reflecting pump light and Raman light. Finally, a detection limit of 5% for ethanol solution and an enhancement factor of two compared with direct detection of bulk sample volume are demonstrated. Above all, our device can be utilized as a Raman probe extension kit, which is suitable for rapid, sensitive, and in situ measurements for a few microliter level samples.