Near Field Transducer for Heat Assisted Magnetic Recording

An antenna for heat assisted magnetic recording is disclosed. The antenna includes an optically opaque material and an optically transparent material positioned on the optically opaque material, the optically transparent material includes a half bowtie shape which includes a first half-wing substantially shaped in form of a right angle trapezoid, having a height substantially equal to the overall height of the half bowtie, a second half-wing Substantially shaped in form of a mirror image of the first half-wing and formed proximate and coupled to the first half-wing by a Substantially rectangular aperture having an aperture width and an aperture height. The aperture height is as Small as 1 nm

Reduction in coherent phonon lifetime in Bi2Te3/Sb2Te3 superlattices

Femtosecond pulses are used to excite A(1g) optical phonons in Bi2Te3, Sb2Te3, and Bi2Te3/Sb2Te3 superlattice. Time-resolved reflectivity measurements show both the low-frequency and high-frequency components of A(1g) phonon modes. By comparing the phonon lifetime, it is found that the scattering rate (inverse of lifetime) in superlattice is significantly higher than those in Bi2Te3 and Sb2Te3. This represents the direct measurement of coherent phonon lifetime reduction in superlattice structures, consistent with the observed reduction in thermal conductivity in superlattices. (c) 2008 American Institute of Physics

Characterization of Novel Photoresists for STED-enhanced Nanolithography

Stimulated emission depletion (STED) applied to nanolithography has greatly improved achievable resolutions and quality of nanoscale structures. The special resin used, called a photoresist, is currently the major limiting factor in further improvement in resolution and structure quality. Characterizing new formulations of photoresists and comparing their performance in STED-enhanced nanolithography to the performance of current formulations will allow for greater resolution and structure quality. With each photoresist, line structures are produced with a two-laser system including a writing, or excitation, laser and a depletion, or STED, laser. The line structures are exposed to the STED laser for a short duration in each experiment. The average powers of the excitation and STED lasers are varied to obtain a writing and depletion threshold where quality and resolution are observable through scanning electron microscope (SEM) imaging. A photoresist currently used was compared to the same photoresist with the stabilizing photoinhibitor removed. The photoresist with the photoinhibitor removed demonstrated promising characteristics, however further experimentation is required to determine whether the new photoresist is better suited for STED-enhanced nanolithography

Development of a Nanomanufacturing Process to Produce Atomically Thin Black Phosphorus

Atomically thin black phosphorus (phosphorene) has both unique and desirable properties that differ from bulk black phosphorus. Unlike graphene, phosphorene has a bandgap, which makes it potentially useful for applications in the next generation of transistors. Large-scale applications of phosphorene, like other 2D materials, are limited by current production methods. The most common method of making phosphorene is mechanical exfoliation, which can only produce small and irregular quantities. In this work we investigate a top-down method of producing phosphorene by using a scanning ultrafast laser to thin black phosphorus flakes. Because the bandgap of phosphorene increases as layers are removed, it is anticipated that the last few layers will be harder to remove using the laser than the upper layers. Hopefully with properly tuned laser parameters, all but the last layer can be removed. Using a custom laser machining setup, the effects of laser power, wavelength, and scanning speed on ablation phenomena are investigated. After laser processing, flakes are characterized using Raman spectroscopy and atomic force microscopy in order to determine the nature and thickness of exposed regions. Tests done at 400 nm wavelength showed removal of material with comparatively weaker Raman peaks in the exposed areas, indicative of thinning. Removal of material was observed at 800 nm and 1500 nm wavelengths, but absence of Raman peaks indicated that thinned regions had melted and recrystallized, becoming amorphous. The present work sets the foundation for future experiments to refine this process and further explore the physics governing the thinning phenomenon

Extraordinary infrared transmission through a periodic bowtie aperture array,” Opt

The discovery of extraordinary transmission through periodic aperture arrays has generated significant interest. Most studies have used circular apertures and attributed enhanced transmission to surface plasmon polariton (SPP) resonances and/or Rayleigh-Wood anomalies (RWA). Bowtie apertures concentrate light and have much longer cutoff wavelengths than circular apertures and can be designed to be strongly resonant. We demonstrate here that the total transmission through a bowtie aperture array can exceed 85% (4ϫ the open area). Furthermore, we show that the high transmission is due to waveguide modes as opposed to the commonly believed SPP/RW phenomena. This work is focused on IR wavelengths near 9 m; however, the results are broadly applicable and can be extended to optical frequencies. © 2010 Optical Society of America OCIS codes: 240.0240, 240.6680, 050.1220. Classical aperture theory predicts that transmission through a subwavelength hole scales with ͑d / ͒ 4 , where d is the diameter of the aperture and is the free-space wavelength of light In this Letter we investigate transmission through a periodic array of bowtie apertures. The transmission modes are optimized to obtain high transmission around =9 m. The high transmission in IR has the potential as a high-efficiency IR coupler for detection devices. The bowtie aperture is also polarization selective, therefore useful where polarization selectivity is of interest such as IR polarimetry imaging Bowtie apertures are one type of ridge aperture The geometry of the bowtie aperture array studied in this work is shown in 992 OPTICS LETTERS / Vol. 35

High precision dynamic alignment and gap control for optical near-field nanolithography

The authors demonstrate the use of interferometric-spatial-phase-imaging (ISPI) to control a gap distance of the order of nanometers for parallel optical near-field nanolithography. In optical near-field nanolithography, the distance between the optical mask and the substrate needs to be controlled within tens of nanometers or less. The ISPI technique creates interference fringes from checkerboard gratings fabricated on the optical mask, which are used to determine the gap distance between the mask and the substrate surfaces. The sensitive of this gapping technique can reach 0.15 nm. With the use of ISPI and a dynamic feedback control system, the authors can precisely align the mask and the substrate and keep variation of the gap distance below 6 nm to realize parallel nanolithography. (C) 2013 American Vacuum Society

Optical nanolithography with λ/15 resolution using bowtie aperture array

We report optical parallel nanolithography using bowtie apertures with the help of the interferometric-spatial-phase-imaging (ISPI) technique. The ISPI system can detect and control the distance between the bowtie aperture, and photoresist with a resolution of sub-nanometer level. It overcomes the difficulties brought by the light divergence of bowtie apertures. Parallel nanolithography with feature size of 22 ± 5 nm is achieved. This technique combines high resolution, parallel throughput, and low cost, which is promising for practical applications.United States. Defense Advanced Research Projects Agency (Grant N66001-08-1-2037)National Science Foundation (U.S.) (Grant CMMI-1120577