The effect of femtosecond laser processing conditions on the properties of a polarization imaging filter inside a silica glass

摘要

Real-time acquisition of polarization distribution of light will enable us to treat new image information and give us new application of image acquisition. A polarization imaging filter, which is used to obtain a polarization distribution in realtime, is consist of two-dimensionally arrayed polarizers or waveplates of different orientations. A polarization imaging filter of waveplate-type can be fabricated by inscribing birefringent structure inside a silica glass by focused ultrashort laser pulses. Larger retardance and higher transmittance of a filter are required to acquire the polarization with a higher sensitivity. However, transmittance through inscribed birefringent structures decreases with increasing retardance. Therefore, it is necessary to elucidate the laser processing conditions to obtain larger retardance with maintaining transmittance as possible. In this study, we investigated processing characteristics such as retardance and transmittance which determine the performance of a polarization filter.