Polarization selective computer-generated holograms realized in glass by femtosecond laser induced nanogratings

We demonstrate polarization selective computer-generated holograms (PSCGH) for visible light operation fabricated in glass by a femtosecond laser. For this purpose we create arrays of tailored microwaveplates by controlling the laser formation of nanogratings embedded in fused silica. A birefringent cell-oriented encoding method adapted to the characteristics of the physical writing process is proposed and implemented. According to this method, each cell contains a micro-waveplate with controlled phase retardation and orientation. A detour of each microwaveplate, combined with the orientation of its principal optical axis, simultaneously realizes a different phase function for each polarization. PSCGH's are attractive for integration with other free-space and guided-wave devices embedded in glass.