Recent efforts to define microscopic solid-immersion-lenses (SIL) by focused ion beam milling into diamond substrates that are registered to a preselected single photon emitter are summarized. We show how we determine the position of a single emitter with at least 100 nm lateral and 500 nm axial accuracy, and how the milling procedure is optimized. The characteristics of a single emitter, a Nitrogen Vacancy (NV) center in diamond, are measured before and after producing the SIL and compared with each other. A count rate of 1.0 million counts per second is achieved with a [111] oriented NV center.
Investigations of two-photon polymerization (TPP) with sub-100 nm in the structuring resolution are presented by using photosensitive sol-gel material. The high photosensitivity of this material allows for TPP using a large variety in laser pulse durations covering a range between sub-10 fs and ≈140 fs. In this study, the authors demonstrate TPP structuring to obtain sub-100 nm in resolution by different approaches, namely, by adding a cross-linker to the material and polymerization with sub-10 fs short pulses. Additionally, a simulation and model based characterization method for periodic sub-100 nm structures was implemented and applied in an experimental white light interference Fourier-Scatterometry setup.
Time-differential length change measurements after temperature changes were developed and applied to the study of high-temperature atomic defect in the case of intermetallic alloys. The enthalpies H F 1 1.0 6 0.1 eV or H E 1 1.5 6 0.2 eV derived for B2-Fe 55 Al 45 from the temperature-dependent amplitudes and time constants of the length change, respectively, coincide with the vacancy formation and migration enthalpies H F V and H M V from earlier positron studies. This demonstrates the feasibility of the technique. By this technique, for the first time, the enthalpies H M V 1.8 6 0.1 eV and H F V 1.5 6 0.25 eV in B2-Ni 47 Al 53 were determined. [S0031-9007(98)08324-0] PACS numbers: 61.72.Ji, 07.60.Ly, 61.66.Dk, 66.30.FqAtomic defects in thermal equilibrium at high temperatures in metals or intermetallic compounds are involved in a number of solid state processes such as structural orderdisorder transition [1], self-diffusion [2], or mechanical creep [3]. For the investigation of thermal defects techniques are required which are specific for the detection of these defects, sensitive to low atomic concentrations, and applicable at high temperatures. Positron lifetime studies (see [4]) and concomitant ab initio calculations [5] have contributed substantial progress to the studies of thermal defect formation and migration in intermetallic compounds. Positron annihilation studies are, however, inappropriate for more complex systems with structural vacancies or free volumes so that more versatile techniques are desirable. Here, we demonstrate that time-differential length change measurements can be successfully employed as a sensitive technique for defect formation and migration studies. This method will be, in addition, of general and wide interest for sensitive studies of condensed matter kinetics.A time-dependent length change Dl͑t, T i , T f ͒ of a specimen is expected when the thermal defect concentrations equilibrate after a fast temperature change between the initial and final temperatures T i and T f (Fig. 1). The temperature variation of this behavior yields direct information on defect formation and migration as well as on the vacancy formation volume DV if the absolute values of atomic defect concentrations are available [6,7]. This technique is furthermore specific to the thermal formation of vacancies or interstitials which are expected to give rise to either an expansion or a contraction [8], respectively.The length change kinetics after temperature changes were studied earlier [9] by a mechanical probe. For the present thermal defect studies by high-precision timedifferential dilatometry [10] an incremental Michelson laser intereferometer was employed which permits contactfree length change measurements up to high temperatures without contamination. For the first time, defect formation as well as migration in the vicinity of thermal equilibrium could be studied by means of this technique.The time dependence of the length change Dl͑t, T i , T f ͒ after a temperature change (see Fig. 1) originates from th...
Early formulations of the RCWA yield, implicated by the erroneous application of factorization rules to discrete Fourier transformations, poor convergence in certain cases. An explanation for this finding and an approach to overcome the problem for crossed gratings was first given by Li [J. Opt. Soc. Am. A 13, 1870 (1996) and 14, 2758 (1997)]. A further improvement was achieved by Schuster et al. [J. Opt. Soc. Am. A 24, 2880 (2007)], using a structure dependent normal vector (NV) field. While it is trivial to create those NV fields for simple geometrical shapes, to our knowledge an appropriate algorithm for arbitrary shapes does not exist, yet. In this work we present such an algorithm.
Scatterometry is a well-established, fast and precise optical metrology method used for the characterization of sub-lambda periodic features. The Fourier scatterometry method, by analyzing the Fourier plane, makes it possible to collect the angle-resolved diffraction spectrum without any mechanical scanning. To improve the depth sensitivity of this method, we combine it with white light interferometry. We show the exemplary application of the method on a silicon line grating. To characterize the sub-lambda features of the grating structures, we apply a model-based reconstruction approach by comparing simulated and measured spectra. All simulations are based on the rigorous coupled-wave analysis method.
Due to plasmonic excitations, metallic meander structures exhibit an extraordinarily high transmission within a well-defined pass band. Within this frequency range, they behave like almost ideal linear polarizers, can induce large phase retardation between s-and p-polarized light and show a high polarization conversion efficiency. Due to these properties, meander structures can interact very effectively with polarized light. In this report, we suggest a novel polarization scrambler design using spatially distributed metallic meander structures with random angular orientations. The whole device has an optical response averaged over all pixel orientations within the incident beam diameter. We characterize the depolarizing properties of the suggested polarization scrambler with the Mueller matrix and investigate both single layer and stacked meander structures at different frequencies. The presented polarization scrambler can be flexibly designed to work at any wavelength in the visible range with a bandwidth of up to 100 THz. With our preliminary design, we achieve depolarization rates larger than 50% for arbitrarily polarized monochromatic and narrow-band light. Circularly polarized light could be depolarized by up to 95% at 600 THz.
In Fourier modal methods like the RCWA and the Differential Method the Li-rules for products in truncated Fourier space have to be obeyed in order to achieve good convergence of the results with respect to the mode number. The Lirules have to be applied differently for parts of the field that are tangential and orthogonal to material boundaries. This is achieved in the Differential Method by including a field of vectors in the calculation that are normal to the material boundaries. The same can be done laterally in each layer of an RCWA calculation of a 2-D periodic structure. It turns out that discontinuities in the normal vector field can disturb the computation especially when metallic materials are dominant in the structure which would make the usefulness of the normal vector method questionable. So it is of great importance to investigate how normal vector fields can be established with as few discontinuities as possible. We present various methods for the 2-D RCWA and the 1-D and 2-D Differential Method and compare the respective convergence behaviors. Especially we emphasize methods that are automatic and require as few user input as possible.
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