Fig. 1: Femtosecond laser direct writing of birefringent modification by different ellipticities of the beam.
From: Efficient ultrafast laser writing with elliptical polarization
a The birefringence image of voxels imprinted by 30 pulses. Pseudo colors (inset) indicate the local orientation of the slow axis. b Retardance of type X modification as a function of ellipticity for 20 or 30 pulses with the energy of 200 nJ. c and d Retardance for birefringent voxels versus ellipticity with pulse energy of 220 nJ at different pulse numbers. Processing conditions: 1 MHz repetition rate, 300 fs pulse duration, 1030 nm wavelength, 0.3 NA lens
