Research On Zeeman Frequency-stabilized Laser For SPR Sensor

Surface plasmon resonance (SPR) optical sensing technique has been widelyapplied and researched in biosensing, food safety, medical and other fields, becauseof its particular superiorities, which are, label-free, high-sensitive andreal-time-sensing. In recent years, with the continuous development of thistechnique, people have placed greater demands on its performance. We find thatlight source for the sensors has a great influence on its measurement precision bystudying SPR sensing technique. Three ways, which would be conductive toimprove the measurement precision of SPR sensing, have been researched, whichare improving SPR phase detection system, using polarization interferometry SPRsensor and inhibiting the laser speckle that is widespread in SPR imaging with laseras light source. After a deep literature research, we find that the He-Ne longitudinalZeeman laser with dual frequency would meet the application requirements of allthe three aspects. The output light of this frequency stabilizated longitudinalZeeman laser contains a pair of orthogonal circularly polarized light, which wouldcause intense interference phenomenon. So an obvious beat frequency signal wouldbe detected from the output light of this laser. This kind of common-pathinterference light source has great application prospects in phase detection SPRsensing system. The circular polarization characteristic of longitudinal Zeeman laserprovides a great convenience for changing the polarization state of the incident lightin the polarization interference modulation techniques. As for the laser speckle, thebeat frequency could fundamentally eliminate the spatial coherence of the lightsource, while beat frequency may have an effect on the speckle suppression. So westart our research from the perspective of the light source for SPR sensor. Afrequency stabilizated longitudinal Zeeman laser with dual frequency has beendesigned and constructed. At last, a series of experiments have been set up todetermine the performance of this frequency stabilizated laser. The results show thatthe frequency stability of this laser is in the order of10-8. Good results have beenobtained from experimental measurement of polarization properties and the spot imaging experiments. In summary, the work in this dissertation has laid thefoundation for the further SPR sensing research work.