Parity violation in chiral structure creation under femtosecond laser irradiation in silica glass?

The paper addresses the creation of circular optical properties from a femtosecond laser light beam with a linear polarization in an achiral material (glass) under an orthogonal incidence. In this situation, all aspects of the experiment are achiral and therefore should not give rise to chiral property creation. From that observation, we propose an interpretation that involves the action of a light-induced torque on the matter carrying a light-induced dielectric moment. We found that a direct current (DC) electric field could be produced in the lattice by the femtosecond laser in our conditions and that a non-collinear dielectric moment is created by a nonlinear effect between the DC electric field and the stress field due to the transformation of the material. We reveal that it is possible to break the chiral symmetry of glass using an intense, ultrashort laser light pulse. Intense, ultrashort laser pulses can break the chiral symmetry of pure silica, find scientists in Paris. Bertrand Poumellec and co-workers from Université Paris Sud and Mines de Paris observed that when the energy of a femtosecond laser pulse exceeds a certain value, silica, which is usually achiral, starts to behave in a chiral manner. This introduced chirality corresponds to an optical rotation of about 5 degrees per millimetre, which is large enough to be useful for practical applications. This unexpected symmetry breaking and chiral activity is conjectured to be due to the creation of a dielectric moment non-collinear with the light electro-magnetic field in the silica, which occurs due to a nonlinear interaction between the laser-induced direct-current electric field and the stress field in the material. The researchers anticipate that this effect could provide a new platform for versatile photonic devices.