Fabrication Of Fabry-Pérot Microcavity Array And Generation Of Optofluidic Laser

The optofluidic laser chip has become a research hotspot in recent years.Because of its high integration,high detection sensitivity,miniaturization,and portable characteristics,it has become an important platform in the field of biochemical medical detection.In optofluidic laser chips,optical microcavities are very important.Fabry-Pérot(FP)microcavities have good compatibility with the microfluidic system,high utilization of gain medium,and are easy to fabricate integrated,etc.FP microcavities are widely used in various biochemical tests such as cell detection,gene detection,etc.At present,a large number of researches on multi-wavelength array lasers have driven the development of optofluidic lasers towards arrays.The fabrication of microcavity arrays is the key to the production of optofluidic array lasers.The realization of optofluidic array lasers has huge application potential,such as wavelength division multiplexing,multi-signal emission and detection,etc.In the previous work,through the CO₂ laser point-by-point processing method,we have fabricated high-quality plano-concave FP microcavity array,which has high quality factors and high finesse,but the array period is large and the mode volume is large.This work is to improve the above existing problems,and we proposed new ideas and methods for processing.At the end,the generation of optofluidic laser in the FP microcavity array was realized.(1)In this work,concave structure array was first fabricated on the substrate of a fused silica and a cover glass by the method of CO₂ laser ablation combining with an optical mask,and the characteristics of the structure were analyzed.We have processed the lattice structures of 3×3 and 5×5 on a fused silica glass substrate and a cover glass substrate,respectively,with a period length of 23.5?m and 26.6?m respectively.Experiment data and simulation analysis show that the concave structure can be approximated to a Gaussian surface with depth t ranging from 0.042-0.64?m and FWHM(full width at half maximum height)d ranging from 11.30-16.60?m;and the bottom surface of the concave structure can be approximated by a spherical surface with a radius of curvature R.Compared with the microcavity array prepared in the previous work,the processing method proposed in this work is convenient,quick,and easy to operate,and has a small pattern size,a small array period length,and a higher degree of integration.(2)Then,FP microcavity array was prepared by dielectric coating and microcavity assembly(plana-plana cavity length is 30?m):stable microcavities can be realized in the formant of a planar mirror and a concave mirror.The generation of optical microfluidic laser in this array microcavity was tested by the method of CCD image acquisition and spectrum acquisition.A nanosecond laser with a wavelength of 532 nm is used as a pump source,and 1 m M rhodamine 6G dissolved in absolute ethanol is used as a gain dye.Multiple optofluidic laser can be observed under a laser pump energy of 38.2?J/mm².Experimental measurement and analysis simulation show that the pump laser threshold of the optofluidic array lasers in this microcavity array is about 13.5?J/mm².Due to the difficulty of spectral resolution of the emitted multimode laser,this work achieves spectral separation by shortening the cavity length(plana-plana cavity length is 5?m),which is beneficial to spectral analysis and application.This work promotes the development of optofluidic array lasers based on FP microcavities.Optofluidic array lasers will have wide applications in laser wavelength division multiplexing,multi-signal optofluidic laser generation and detection.