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In-bulk recording without cracking in borosilicate glass by high repetition rate (80 MHz) 12 ps pulses at 355 nm wavelength is demonstrated and discussed. The theoretical model of a "hot-line" scan and thermal accumulation qualitatively well describes the experimental results. The analytical expression of a thermally induced stress was obtained. Recent advances in microfabrication, in which ultrafast lasers with pulse durations of less than 1 ps are implemented, show the potential ability to record sub-µm structures inside transparent materials. 1,2 The nonlinear mechanism of absorption allows the photomodification to be localized within the volume 2 or on the surface 3 with a cross section smaller than the wavelength, . The diffraction limit of the focusing optics can be overcome. However, for some three-dimensional (3D) microstructuring tasks, a high repetition rate (over 200 kHz) is required to achieve partial softening/melting of glass. 4 Obviously, longer pulses (from picoseconds to nanoseconds) could be considered for this type of recording, however, they usually cause crack formation in glass. Recently, it was demonstrated that brittle materials can also demonstrate a ductile response before onset of crack formation at a specific crossover length of order 10 nm in glass. 5 Control of the local temperature and its distribution inside transparent materials at the focus allows one to tune a thermal stress for a desired application, e.g., a 3D dicing (a controlled cleaving) would require a controlled crack propagation, while the optical memory and waveguide recording would benefit from prevention of the crack formation by material softening/ melting.The aim of this work was to investigate the effect of thermal accumulation on 3D laser recording by 12 ps duration, 355 nm wavelength pulses at a high (80 MHz) repetition rate inside glass. The experimental results are compared with those of theoretical modeling.A Vanguard (Spectra Physics) laser was used for 3D recording inside borosilicate slide glass (Corning 2947). Recording was carried out by beam scanning with galvano mirrors at a constant speed of 5-10 cm/s using -lens focusing, which fixed the focal depth along the line of recording inside the 1-mm-thick samples (aimed at the center). The pulse duration was 12 ps, the repetition rate 80 MHz, the maximum pulse energy 50 nJ, and the wavelength 355 nm. In-bulk laser fabrication is possible at this wavelength because the main absorption mechanism is a nonlinear two-photon absorption (TPA). The TPA coefficient of slide glass ␤ = 25± 7 cm/ GW was directly measured at 355 nm using by the transmission method applicable when linear absorption is negligible. 6 The edge of glass absorption was at approximately 320 nm wavelength where the decadic optical density ͑OD͒ Ͼ 0.1 for a 1-mm-thick glass; while the linear absorption coefficient at 355 nm was only ␣ 0 = 0.47 cm −1 .For recording, we used focusing defined by f-number ͑f # ͒ = 10, at which a cost-efficient diffraction-limited performance of lens can be achieved. ...

PACS. 74.60.Ec -Mixed state, critical fields, and surface sheath.Abstract. -The field-dependent critical current Ic(H) and current-voltage characteristics are found within a generalized critical-state model that accounts for both surface barrier and bulk pinning as major irreversibility mechanisms in type-II superconductors. Calculations are made for an exactly solvable case of a thin-film superconductor taking into account the GinzburgLandau nonlinearity of the order-parameter equation. The shape of the current-voltage characteristics of the film is determined for arbitrary magnetic field. The nonmonotonous field dependence of the differential film resistivity is discovered, which is characterized by a negative magnetoresistance in a low-field region and by the Bardeen-Stephen-like behaviour in a high-field region.Introduction. -The edge/surface barrier effect on transport properties of type-two superconductors is at present under extensive investigation. The essential barrier influence on superconductor resistivity, that arises due to thermoactivative barrier overcoming, was recently demonstrated in [1, 2] on Bi-based single crystals with high demagnetization factor. The importance of surface barrier (SB) for a wide range of materials (including low-T c superconductors [3]) in affecting the transport as well as the magnetic properties of superconductors is at present widely recognized. The interplay between the barrier and bulk pinning being responsible for the emergence of the nontrivial magnetic flux structures in an external magnetic field [4,5] or in a transport-current-carry state [6,7] to a great extent determines both magnetic and resistive characteristics of low-dimensional superconductors.Some progress in describing magnetization features of superconducting samples with a reduced dimensionality (thin-film or single-crystalline sample with high demagnetization) is due to a highly developed technique employed to solve the corresponding integral equations [4,6]. However, the essentially long-range intervortex repulsion complicates significantly the theoretical investigation of the transport properties of superconductors with a high demagnetization factor. Therefore it is highly desirable to formulate an exactly solvable model of the critical/resistive state in thin-film superconductors, which accounts for major irreversibility mechanisms (edge barrier and bulk pinning).In the present letter we provide first a self-consistent consideration of the combined influence of the edge barrier and bulk pinning on the field dependence of the critical current, the

The influence of both bulk and edge pinning on the response of a thin-film superconductor to an oscillating magnetic field is considered. The magnetic-flux-defreezing field and the flux-exit field are defined. The hysteresis and magnetization curves of a sample are constructed for the entire cycle of the magnetic field. From this, we obtain the dependence of the hysteresis losses on the field amplitude.