Holographic fabrication of diamondlike photonic crystal template using two-dimensional diffractive optical elements

This letter demonstrates holographic fabrication of three-dimensional diamondlike photonic crystal templates in SU8 photoresist using a single diffractive optical element. Five coherent laser beams produced by a two-dimensional phase mask were used to construct face-centered-cubic or tetragonal interference patterns. The superposition of two interference patterns through double exposures yields diamondlike photonic crystal templates in SU8. Photonic bandgap calculation reveals a full bandgap in inverse structures based on the template. The utilization of the two-dimensional phase mask simplifies the fabrication configuration in multiple beam holographic lithography for three-dimensional photonic fabrication. © 2008 American Institute of Physics

Undistorted 3D microstructures in SU8 formed through two-photon polymerization

This paper presents the wavelength dependence of two-photon polymerization in SU-8 between 720-780 nm. The study is performed by microstructuring SU-8 through a single-shot exposure of SU-8 to 140 fs tunable laser pulses with 80 MHz repetition rate, or by laser direct writing. Two-photon absorption is closely related to one-photon absorption in pristine SU-8. By careful design of the neighboring micro-structures, or by varying wet-processing parameters during development, undistorted and unbended 3D micro-structures have been fabricated through direct laser writing. © 2011 Author(s)

Photonic crystals with defect structures fabricated through a combination of holographic lithography and two-photon lithography

This paper presents the capability of direct laser writing of complex defect structures in holographically formed three-dimensional photonic crystals in dipentaerythritol penta/hexaacrylate (DPHPA) monomers mixed with photoinitiators. The three-dimensional photonic crystal template was fabricated through prism-based holographic lithography. Defect structures are fabricated through the two-photon polymerization excited by a femtosecond laser. The strengths of two optical lithographic techniques are combined with holographic lithography providing a rapid and large area microfabrication and two-photon lithography providing flexibility in fabrication of defect structures. The optical fabrication process is simplified in the negative tone DPHPA without prebake and postexposure bake as is required of SU-8 while maintaining a capability for constructing photonic structures with small features. © 2010 American Institute of Physics

Holographic fabrication of three-dimensional orthorhombic and tetragonal photonic crystal templates using a diffractive optical element

We report the fabrication of both orthorhombic and tetragonal photonic crystal templates using a phase mask technique. Three-dimensional photonic crystal structures were formed by a double exposure of SU8 to three-beam interference patterns generated by a phase mask. Lattice structures and photonic band gap can be controlled by rotational angles of the phase mask between two exposures. Band gap computation predicts that photonic crystal structures with the optimized band gap can be realized when the rotational angle is set between 50° and 70°. A photonic crystal template with 60° phase mask rotation was fabricated, showing improved lattice structures required for the band gap opening. © 2007 American Institute of Physics

A tunable three layer phase mask for single laser exposure 3D photonic crystal generations: bandgap simulation and holographic fabrication

Through the use of a multi-layer phase mask to produce five-beam interference, three-dimensional photonic crystals can be formed through single exposure to a photoresist. In these holographically formed structures, the interconnectivity is controlled by the relative phase difference among contributing beams. Photonic band gaps are calculated and the simulation shows a maximum bandgap of 18% of the middle gap frequency when the phase difference is optimized. A three-layer phase mask is fabricated by placing a spacer layer between two orthogonally-orientated gratings. The phase difference is controlled by thermal-tuning of the spacer thickness. Photonic crystal templates are holographically fabricated in a photosensitive polymer using the phase mask

Holographically formed three-dimensional Penrose-type photonic quasicrystal through a lab-made single diffractive optical element

Large-area three-dimensional Penrose-type photonic quasicrystals are fabricated through a holographic lithography method using a lab-made diffractive optical element and a single laser exposure. The diffractive optical element consists of five polymer gratings symmetrically orientated around a central opening. The fabricated Penrose-type photonic quasicrystal shows ten-fold rotational symmetry. The Laue diffraction pattern from the photonic quasi-crystal is observed to be similar to that of the traditional alloy quasi-crystal. A golden ratio of 1.618 is also observed for the radii of diffraction rings, which has not been observed before in artificial photonic quasicrystals. © 2010 Optical Society of America

THE POWER OF THE WRITTEN ASSERTION

In his Outline of History Mr. Wells comments on the exaggerated estimate which people generally, through reading the Old Testament account, have come to entertain of the wisdom of Solomon and of the glory and prestige of the Israelitish Kingdom during his reign. By way of contrast, the facts, which are readily available and discernable even in the scriptural narrative, reveal this much advertised monarch as a rather insignificant chieftain and his kingdom as a pawn in the policies of his powerful neighbors-a striking example, according to Mr. Wells, of the power of the written assertion over realities in men\u27s minds

LIMITATION OF DIVERSITY JURISDICTION IN CASES AFFECTING FOREIGN CORPORATIONS

On February 29, 1932, President Hoover sent to the Senate and House of Representatives a message recommending that the jurisdiction of federal courts based on diversity of citizenship be modified by providing that where a corporation, organized under the laws of one State, carries on business in another State it shall be treated as a citizen of the State wherein it carries on business as respects suits brought within that State between it and the residents thereof arising out of the business carried on in such State