Dynamic aberration correction via spatial light modulator (SLM) for femtosecond direct laser writing: towards spherical voxels.

Optical aberrations are a type of optical defect of imaging systems that hinder femtosecond direct laser write machining by changing voxel size and aspect ratio in different sample depths. We present an approach of compensating such aberrations using a liquid crystal spatial light modulator (SLM). Two methods for correcting are explored.

Stitchless support-free 3D printing of free-form micromechanical structures with feature size on-demand.

Femtosecond laser based 3D nanolithography is a powerful tool for fabricating various functional micro- and nano-objects. In this work we present several advances needed to push it from the laboratory level use to the industrial production lines. First, linear stage and galvo-scanners synchronization is employed to produce stitch-free mm-sized structures.

Photonic crystal spatial filters fabricated by femtosecond pulsed Bessel beam.

We propose and experimentally demonstrate femtosecond direct laser writing with Bessel beams for the fabrication of photonic crystals with spatial filtering functionality. Such filters are mechanically stable, of small (of the order of a millimeter) size, do not require direct access to the far-field domain, and therefore are excellent candidates for intracavity spatial filtering applications in minilasers and microlasers. The proposed technique allows the fabrication of photonic crystal filters in inorganic glass, with a narrow angle (∼1°) nearly 100%-transmission passband between a broad angle (∼10°) nearly 0%-transmission angular stopbands.

Photonic Crystal Microchip Laser.

The microchip lasers, being very compact and efficient sources of coherent light, suffer from one serious drawback: low spatial quality of the beam strongly reducing the brightness of emitted radiation. Attempts to improve the beam quality, such as pump-beam guiding, external feedback, either strongly reduce the emission power, or drastically increase the size and complexity of the lasers. Here it is proposed that specially designed photonic crystal in the cavity of a microchip laser, can significantly improve the beam quality.

Spatial filtering by axisymmetric photonic microstructures.

We propose and show experimentally axisymmetric spatial (angular) filtering of two-dimensional light beams by axisymmetric photonic microstructures. Such three-dimensional microstructures (similar to photonic crystals), in gapless configuration, were recorded in bulk of glass, where the refractive index has been point-by-point modulated using tightly focused femtosecond laser pulses. Axisymmetric angular filtering of approximately 25 mrad is demonstrated experimentally.