On-chip Quantum Dot Microcavity Lasers And Biosensing Based On Inkjet Printing Technology

Quantum dot materials have become one of the most promising materials in photoelectric devices due to their high quantum yield,wide emission wavelength tunability and good process compatibility.Among many optical microcavities,the characteristics of high-quality factor,small mode volume and micron-scale size of whispering gallery mode microcavities have aroused strong interest,and are widely used in the fields of microcavity lasers and optical sensing.The combination of whispering gallery mode microcavity and quantum dot gain is a reliable scheme to achieve high performance on-chip microcavity lasers.However,the high-quality factor of optical microcavity or the cavity template with high precision is limited to the large-scale manufacturing of low-cost quantum dot microcavity lasers.Therefore,this thesis combined the simple,efficient and low-cost inkjet printing method with Cd Se/Zn S colloidal quantum dots to fabricate on-chip quantum dot microcavity lasers,and explored the potential of defection assisted quantum dot microring lasers in biosensing applications.At present,the main research results are as follows:1.According to the principle of inkjet printing technology,a simple inkjet printing device was designed,which was used to fabricate quantum dot microcavity lasers on substrate film.By adjusting the printing parameters,quantum dot microcavity lasers with different structures were obtained,including asymmetric microcavity,microdisk cavity and microring cavity.2.The quantum dot microcavity lasers with different structures were characterized.Among them,a large number of disordered modes of asymmetric microcavity lasers and microdisk lasers led to mode stacking in the laser spectrum.However,the spacing between adjacent modes of the microring lasers was large,and each resonant mode could be clearly distinguished,thus obtaining a pure laser spectrum.The subsequent analysis of the optical properties of the quantum dot microring lasers showed that the lasing threshold was as low as 22.9μJ/mm~2,the minimum excited structure diameter was about 30μm,the quality factor was as high as 2783,and the free spectrum range was 2.1nm.Under the condition of high pump energy density,the microring lasers maintained good spectral stability and working life.3.Characterized the optical properties of quantum dot microring lasers in water,it was found that the presence of defects caused the solution to penetrate into the microring cavity,reducing the effective refractive index of the mode and resulting in a spectral blue-shift phenomenon.Based on the spectral blue-shift phenomenon,biological solution sensing experiments were subsequently carried out.In the glucose solution sensing experiment,the mode shifts of the microring lasers increased with the increased of the refractive index of the solution,which proved the potential of the quantum dot microring lasers in biosensing applications.In the bovine serum albumin solution sensing experiment,the mode shifts of the microring lasers with more defects in the same concentration solution was larger than that of the one with less defects,which proved the effect of surface defects on the sensing performance.