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The technology of fabricating photonic crystals with the use of nanoimprint lithography is described. One- and two-dimensional photonic crystals are produced by direct extrusion of polymethyl methacrylate by Si moulds obtained via interference lithography and reactive ion etching. The period of 2D photonic crystals, which present a square array of holes, ranges from 270 to 700 nm; the aperture diameter amounts to the half-period of the structure. The holes are round-shaped with even edges. One-dimensional GaAs-based photonic crystals are fabricated by reactive ion etching of GaAs to a depth of 1 μm through a mask formed using nanoimprint lithography. The resulting crystals have a period of 800 nm, a ridge width of 200 nm, and smooth nearly vertical side walls. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

The well-known effect of the local interaction between graphene and photoresist (LIGF) during the creation of biosensors is shown to lead to non-uniform distribution of compressive stresses, which deteriorates the adsorption properties of graphene, parameter reproducibility, and detecting ability of influenza B and SARS-Cov-2 biosensors. It is also shown that controlling the occurrence of LIGF areas on a graphene surface by atomic force microscopy or introducing a protective layer between graphene and photoresist can minimize the non-persistent effect of LIGF. The results of influenza B and SARS-CoV-2 imaging on the graphene surface in biosensor chips in a scanning electron microscope are presented. [ABSTRACT FROM AUTHOR]

A two-dimensional photonic crystal with hexagonal lattice of air-holes is patterned into an active planar waveguide containing InAs/InGaAs quantum dots. Variable-angle reflectivity spectroscopy is used to map out the photonic band structure. Fano-type resonances observed in the measured reflectivity spectra in TE (TM) polarizations along the Γ–K (Γ–M) lattice direction are attributed to resonance coupling of the optically active photonic bands to external light. Angle-resolved photoluminescence measurements are shown to trace the band structure of the leaky mode. The revealed three-fold emission intensity enhancement of photonic crystals is ascribed to both Purcell and Bragg scattering effects. [ABSTRACT FROM AUTHOR]

Under study are temperature dependences of laser characteristics of a GaAs/(AlGa)xOy microdisk of 6 μm in diameter, fabricated using optical lithography, ion milling with a beam of Ar+ ions, and selective oxidation of the Al0.97Ga0.03As layer which forms the microdisk base. In As/InGaAs QDs are used as the microdisk active region. Room-temperature lasing in the 1.3-μm range is observed, with the threshold optical pumping power of 160 μW. The quality factor of microdisk modes is about 104. [ABSTRACT FROM AUTHOR]