Fig. 1: Laser writing of birefringence structures inside silica glass.
From: Ultralow-loss geometric phase and polarization shaping by ultrafast laser writing in silica glass
a Illustration of patterning of birefringence in silica glass by femtosecond laser direct writing. b and c Birefringence and transmission optical microscope images of birefringence structures with high-loss (type II) and low-loss modifications (type X), respectively. To obtain comparable retardance, one birefringent layer was written for b, while 10 birefringent layers were written for c. The colour scale in b indicates the slow axis of the birefringence. d Photograph of birefringent optics imprinted with high-loss (left) and low-loss (right) modifications in silica glass plates. e Transmission spectra of birefringent structures of high-loss (red dashed line) and low-loss (blue solid line) modifications with reference to pristine silica glass. The vertical dotted line indicates a wavelength of 330 nm, at which the transmission for the low-loss modification is 90%. The inset shows the transmission spectra of the low-loss modification (blue solid line) and pristine silica glass (green dashed line)
