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 order of millimeter) size, do not require direct access to the far-field domain, and therefore are excellent candidates for intracavity spatial filtering applications in mini- and micro-lasers. The technique allows the fabrication of efficient photonic crystal spatial filters in glass, with a narrow angle (~1 degree) nearly 100%-transmission pass-band between broad angle (up to 10 degrees) nearly 0%-transmission angular stop-bands. We show, that this technique can not only significantly shorten the fabrication time, but also allows the fabrication of large-scale defect-free photonic crystal spatial filters with a wide filtering band

Spatial Filters on Demand Based on Aperiodic Photonic Crystals

Photonic Crystal spatial filters, apart from stand-alone spatial filtering function, can also suppress multi-transverse-mode operation in laser resonators. Here it is shown that such photonic crystals can be designed by solving the inverse problem: for a given spatial filtering profile. Optimized Photonic Crystal filters were fabricated in photosensitive glass. Experiments have shown that such filters provide a more pronounced filtering effect for total and partial transmissivity conditions.Peer ReviewedPostprint (published version

Chirped photonic crystal for spatially filtered optical feedback to a broad-area laser

We derive and analyze an efficient model for reinjection of spatially filtered optical feedback from an external resonator to a broad area, edge emitting semiconductor laser diode. Spatial filtering is achieved by a chirped photonic crystal, with variable periodicity along the optical axis and negligible resonant backscattering. The optimal chirp is obtained from a genetic algorithm, which yields solutions that are robust against perturbations. Extensive numerical simulations of the composite system with our optoelectronic solver indicate that spatially filtered reinjection enhances lower-order transversal optical modes in the laser diode and, consequently, improves the spatial beam quality

Chirped photonic crystal for spatially filtered optical feedback to a broad-area laser

We derive and analyze an efficient model for reinjection of spatially filtered optical feedback from an external resonator to a broad area, edge emitting semiconductor laser diode. Spatial filtering is achieved by a chirped photonic crystal, with variable periodicity along the optical axis and negligible resonant backscattering. The optimal chirp is obtained from a genetic algorithm, which yields solutions that are robust against perturbations. Extensive numerical simulations of the composite system with our optoelectronic solver indicate that spatially filtered reinjection enhances lower-order transversal optical modes in the laser diode and, consequently, improves the spatial beam quality

Trimačiai fotoniniai kristalai: formavimas ir taikymas chromatinių bei erdvinių šviesos savybių valdymui

Light propagation in photonic crystals is governed by their dispersion properties, which can be controlled by precisely selecting photonic crystal parameters. In such a way, various and sometimes exotic phenomena can be realized. Three-dimensional photonic crystals have the highest number of possible phenomenon, but on the other hand, such crystals are the most difficult to fabricate due to the lack of suitable technologies. In this Thesis it is shown, that various light propagation phenomena (structural colors, flat lensing, spatial filtering and super-collimation) can be realized in photonic crystals with larger and technologically less demanding periods, mainly by using higher order photonic bands dispersion properties. Such photonic crystals were fabricated by direct laser writing techniques in photopolymers and glasses. Their performance was evaluated both experimentally and numerically

Three-dimensional photonic crystals: fabrication and applications for control of chromatic and spatial light properties

Light propagation in photonic crystals is governed by their dispersion properties, which can be controlled by precisely selecting photonic crystal parameters. In such a way, various and sometimes exotic phenomena can be realized. Three-dimensional photonic crystals have the highest number of possible phenomenon, but on the other hand, such crystals are the most difficult to fabricate due to the lack of suitable technologies. In this Thesis it is shown, that various light propagation phenomena (structural colors, flat lensing, spatial filtering and super-collimation) can be realized in photonic crystals with larger and technologically less demanding periods, mainly by using higher order photonic bands dispersion properties. Such photonic crystals were fabricated by direct laser writing techniques in photopolymers and glasses. Their performance was evaluated both experimentally and numerically

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 order of millimeter) size, do not require direct access to the far-field domain, and therefore are excellent candidates for intracavity spatial filtering applications in mini- and micro-lasers. The technique allows the fabrication of efficient photonic crystal spatial filters in glass, with a narrow angle (~1 degree) nearly 100%-transmission pass-band between broad angle (up to 10 degrees) nearly 0%-transmission angular stop-bands. We show, that this technique can not only significantly shorten the fabrication time, but also allows the fabrication of large-scale defect-free photonic crystal spatial filters with a wide filtering band.Peer Reviewe

Reversible deformation in hybrid organic-inorganic photoresists processed by ultrafast direct laser write technique

We report on reversible deformation in photoresist structures patterned using femtosecond direct laser write technique. Significant swelling and shrinkage of exposed features by up to 10% in negative-tone hybrid organicinorganic Zr containing photoresist SZ2080 were found to occur during wet development and rinse following the laser processing. Amount of swelling and shrinkage is controllable within 10% margin via use of different rinse agents and the shrinkage-swelling cycle can be repeated many times. Simple interpretation of this phenomenon is presented, and several potential application areas in diffractive optics, micro mechanics, actuation, and environmental sensing are outlined

Supercollimation of light beams by axisymmetric aperiodic photonic structures

Efficient beam supercollimation is proposed and shown experimentally by axisymmetric aperiodic photonic structures. The structure consists of equidistant layers of concentric refraction index rings, with the transverse period of the rings varying from layer to layer along the structure. Numerically designed and optimized axisymmetric photonic structures are inscribed in silica glass by femtosecond pulses. Strong enhancement (more than by one order of magnitude) of the axial beam component is demonstrated, resulting in the record performance of the beam supercollimation.Postprint (published version

Realization of structural color by direct laser write technique in photoresist

We report realization of structural color in 3D woodpile photonic crystal structures fabricated by femtosecond direct laser write (DLW) lithography in photoresist. The structural color in the fabricated samples was obtained due to spectral regions with high optical reflectivity associated with higher photonic bands well above the fundamental (lowest frequency) photonic stop gap, which allowed realization of visible colors without the need to reduce the lattice period. This advantage facilitates easier and faster DLW fabrication, and can be exploited for realization of structural color materials for various applications, for example optical environmental sensing