Latent image diffraction from submicron photoresist gratings

Light scattering from latent images in photoresist is useful for lithographic tool characterization, process monitoring, and process control. In particular, closed‐loop control of lithographic processes is critical for high yield, low cost device manufacturing. In this work, we report use of pulsed laser diffraction from photoresist latent images in 0.24 μm pitch distributed feedback laser gratings. Gated detection of pulsed light scattering permits high spatial resolution probing using ultraviolet light without altering the latent image. A correlation between latent image and etched grating diffraction efficiencies is demonstrated and shows the value of "upstream" monitoring

Magnetic resonance studies of the fundamental spin-wave modes in individual submicron Cu/NiFe/Cu perpendicularly magnetized disks

Spin wave spectra of perpendicularly magnetized disks with trilayers consisting of a 100 nm permalloy (Py) layer sandwiched by two Cu layers of 30 nm, are measured individually with a Magnetic Resonance Force Microscope (MRFM). It is demonstrated by 3D micromagnetic simulations that in disks having sub-micron size diameters, the lowest energy spin wave mode of the saturated state is not spatially uniform but rather is localized at the center of the Py/Cu interface in the region of a minimum demagnetizing field

Novel parameter estimation schemes in microsystems

This paper presents two novel estimation methods that are designed to enhance our ability of observing, positioning, and physically transforming the objects and/or biological structures in micromanipulation tasks. In order to effectively monitor and position the microobjects, an online calibration method with submicron precision via a recursive least square solution is presented. To provide the adequate information to manipulate the biological structures without damaging the cell or tissue during an injection, a nonlinear spring-mass-damper model is introduced and mechanical properties of a zebrafish embryo are obtained. These two methods are validated on a microassembly workstation and the results are evaluated quantitatively

Magneto-Optical Spectrum Analyzer

We present a method for the investigation of gigahertz magnetization dynamics of single magnetic nano elements. By combining a frequency domain approach with a micro focus Kerr effect detection, a high sensitivity to magnetization dynamics with submicron spatial resolution is achieved. It allows spectra of single nanostructures to be recorded. Results on the uniform precession in soft magnetic platelets are presented.Comment: 5 pages, 7 figure

Locally erasable couplers for optical device testing in silicon on insulator

Wafer scale testing is critical to reducing production costs and increasing production yield. Here we report a method that allows testing of individual optical components within a complex optical integrated circuit. The method is based on diffractive grating couplers, fabricated using lattice damage induced by ion implantation of germanium. These gratings can be erased via localised laser annealing, which is shown to reduce the outcoupling efficiency by over 20 dB after the device testing is completed. Laser annealing was achieved by employing a CW laser, operating at visible wavelengths thus reducing equipment costs and allowing annealing through thick oxide claddings. The process used also retains CMOS compatibility

Grating couplers with an integrated power splitter for high-intensity optical power distribution

In this letter, we present a fiber grating coupler with an integrated 16-way power splitter. The incoming light from the fiber is split immediately over 16 channels, and therefore, the total optical power is never confined in a single waveguide. This is of particular interest for silicon photonics platforms, because, here, high optical intensities can cause significant non-linear losses. The device has a total coupling efficiency that is similar to standard focusing grating couplers. Furthermore, a channel non-uniformity below 1.1 dB has been obtained. By studying the alignment sensitivity, we found that for high splitting uniformity, a careful positioning of the fiber is necessary. We also experimentally demonstrate that this device is indeed capable of handling high optical powers without introducing additional non-linear losses

Dynamical Coulomb Blockade of Shot Noise

We observe the suppression of the finite frequency shot-noise produced by a voltage biased tunnel junction due to its interaction with a single electromagnetic mode of high impedance. The tunnel junction is embedded in a quarter wavelength resonator containing a dense SQUID array providing it with a characteristic impedance in the kOhms range and a resonant frequency tunable in the 4-6 GHz range. Such high impedance gives rise to a sizeable Coulomb blockade on the tunnel junction (roughly 30% reduction in the differential conductance) and allows an efficient measurement of the spectral density of the current fluctuations at the resonator frequency. The observed blockade of shot-noise is found in agreement with an extension of the dynamical Coulomb blockade theory