Study On Polarized Optical-Feedback Cavity Ring-Down Technique Based High Reflectance Measurement

The accurate measurement of high reflectance is very important for thehighly-reflectively coated laser components have been widely used and itsperformance has been greatly improved. The optical feedback cavity ring-down(OF-CRD) technique is better compared with the other high reflectance measurementtechniques such as their costly, complicated, and sensitivity limitations. In this thesissome applications, which are about the high reflectance measurement by using theOF-CRD technique, are researched.The spectrophotometry method, ratiometry method and cavity ring-down methodare summarized, and their limitations are also compared. A combined cavityring-down and spectrophotometry technique is developed and an experiment system isset up with sufficiently high accuracy, which reflectance ranging is from below0.01%to over99.999%. This system is also very simple and easy to use.Many sorts of the polarization and the different reflectance between S and Ppolarized light when injected angle is large enough are introduced. The characteristicfunction of the laser in cavity is deduced when S and P polarized light are existedsynchronously. The double exponential decay theoretical model to describe the outputlaser beam is advanced, and an OF-CRD based experiment system is set up to verifyour theory. Another single exponential fitting method is also put forward to verify ourtheory.The relations, which are between the amplitude of the cavity output signal and thereflectance of the linear and folded cavity, are analyzed in detail. Taking the longitudemode of the cavity and the spectrum of laser beam into consideration, the couplingefficiency function is deduced and some experiments are finished as verification.By using the transfer matrix theories in wave optics and geometric optics, themisalignment and the offset angle of optical resonator are discussed to reduce theinfluence of the errors in experiment and an experiment system is designed tomeasure the remained reflectance and the absorb efficiency.