Abstract: A method of delivering optical energy to a substrate comprises applying a temporal group of optical pulses to a region of the substrate, wherein the temporal group comprises twenty or fewer pulses of a femtosecond pulse duration, arranged as a first subgroup of pulses comprising up to three pulses followed by a second subgroup of pulses comprising the remaining pulses in the temporal group; and wherein energies of the pulses are controlled such that pulses in the first subgroup have a first energy per pulse and pulses in a second subgroup of pulses have a second energy per pulse which is less than the first energy.

Abstract: Examples are disclosed that relate to efficiently producing multiple laser beams of a harmonic frequency from a fundamental frequency beam. One example provides a laser system comprising a laser configured to output a fundamental frequency beam, a first harmonic-generation stage, and a second harmonic-generation stage. The first harmonic-generation stage is configured to receive an input of the fundamental frequency beam from the laser, and output from the laser system a first-stage harmonic frequency beam and a first-stage residual fundamental frequency beam. The second harmonic-generation stage is configured to receive an input of the first-stage residual fundamental frequency beam, and to output from the laser system a second-stage harmonic frequency beam.

Abstract: A method of fabricating an optical element comprises: providing a substrate (1, 50) of a transparent material in which is to be formed a plurality of birefringent nanostructures spaced apart in plane substantially parallel to a surface of the substrate in a first direction (2) by a distance X and in a second direction (3) by a distance Y; generating from the output of a source (20) of femtosecond laser pulses a laser beam group comprising a plurality of focused seeding beams (44) having a circular polarisation and spaced apart along a line by the distance X and a focused writing beam (26) having a non-circular polarisation and spaced apart from one of the seeding beams by the distance Y or the distance X; directing the laser beam group onto the surface of the substrate at a first position and applying one or more femtosecond laser pulses from each beam to corresponding volumes in the substrate; repeatedly translating the laser beam group relative to the substrate parallel to the line of seeding beams and alon

Abstract: A method of fabricating an optical element comprises: providing a substrate of a transparent material; applying a plurality of circularly polarised focused femtosecond laser pulses to a volume within the substrate to create substantially spherical nanopores in the volume; and applying at least one and not more than ten non-circularly polarised focused femtosecond laser pulses to the volume to transform the spherical nanopores into oblate spheroidal nanopores.

Abstract: A method of fabricating an optical element comprises providing a substrate of a transparent material; and applying one or more focused femtosecond pulses of laser light with an elliptical polarisation to a volume within the substrate to create at least one nanostructure in the volume.

Abstract: A method of delivering optical pulses to a substrate comprises directing a focused beam from a source of optical pulses along a propagation direction onto a substrate; moving the substrate relative to the beam in a plane substantially orthogonal to the propagation direction and continuously along a first direction that includes spaced apart row locations on the substrate, and delivering a plurality of optical pulses from source as the beam reaches each row location; and between delivering the optical pulses at consecutive row locations, moving the beam relative to the substrate in one or more successive discrete movements along a second direction in the plane orthogonal to the first direction, to direct the beam to one or more spaced apart column locations on the substrate, and delivering a plurality of optical pulses from the source at each column location.

Abstract: A method of delivering optical energy to a substrate comprises applying a temporal group of optical pulses to a region of the substrate, wherein the temporal group comprises twenty or fewer pulses of a femtosecond pulse duration, arranged as a first subgroup of pulses comprising up to three pulses followed by a second subgroup of pulses comprising the remaining pulses in the temporal group; and wherein energies of the pulses are controlled such that pulses in the first subgroup have a first energy per pulse and pulses in a second subgroup of pulses have a second energy per pulse which is less than the first energy.

Abstract: In a recording technique in which a plurality of light spots are simultaneously formed by using an ultra-short pulse laser and a spatial phase modulator, and a plurality of recording dots having refractive indexes different from those of the vicinities thereof are formed inside a recording medium, it is hard to make recording quality and a recording density compatible. Therefore, a plurality of dots are recorded at a predetermined dot pitch, and then other dots are recorded between the recorded dots.

Abstract: In a recording technique in which a plurality of light spots are simultaneously formed by using an ultra-short pulse laser and a spatial phase modulator, and a plurality of recording dots having refractive indexes different from those of the vicinities thereof are formed inside a recording medium, it is hard to make recording quality and a recording density compatible. Therefore, a plurality of dots are recorded at a predetermined dot pitch, and then other dots are recorded between the recorded dots.