Our research group consists of members of the technical staff at both LLE and COM. Strong collaborative research is ongoing with Prof. Shaw Horng Chen, Prof. Matthew Yates, and Prof. Hong Yang in the Department of Chemical Engineering, and Prof. John Lambropoulos, Prof. Sheryl Gracewski, and Prof. Paul Funkenbusch, who are affiliated with the Department of Mechanical Engineering and the Materials Science Program.

Technical Staff

Mr. Kenneth Marshall is a research engineer in charge of the Liquid Crystal Materials Group at LLE where he also serves as the chemical safety officer. Mr. Marshall supervises students and staff in a variety of research projects. He is quite active in the LLE Summer High School Program.His student, Rui Wang, was an Intel Science Talent finalist in 2006 for her work on computational chemistry modelling.

• Electro-Optical Device Applications in Novel Liquid Crystal Systems
• Phase-Shifting Point-Diffraction Interferometer for Microgravity Fluid Physics (funded by NASA Glenn Research Center, Cleveland, OH). A process for preparing “structured” substrates (those in which the reference diffracting element are an integral part of the substrate, rather than a separately placed element) by means of photoresist processing was developed for the visible region, and ultimately the IR.
• Polymer LC Flake Technology and Applications in Electronic Imaging
• Lyotropic Polysaccharide Liquid Crystal Systems for Optical Applications
• New Materials: A series of new chiral IR dyes with improved solubility in liquid crystals were isolated and characterized. These new dyes show excellent prospects for applications in sensor protection and telecommunications in addition to inertial confinement fusion (ICF) application areas.

• Computational Chemistry: Methodologies are being developed for predicting the dielectric anisotropy and birefringence in low molar mass and polymer liquid crystals using semi-empirical computational chemistry. Work initiated in 2001 to calculate properties in polysiloxane and polymethacrylate LC oligomers with 1-3 repeat units was extended to molecular systems with 10-12 repeat units and initial results were obtained.

Recent Publications and Presentations:

K. L. Marshall, A. Trajkovska-Petkoska, K. Hasman, M. Leitch, G. Cox, T. Z. Kosc, and S. D. Jacobs, “Polymer Cholesteric Liquid Crystal (PCLC) Flakd/Fluid Host Electro-Optical Suspensions and Their Applications in Flexible Reflective Displays”, to be published in the Proceedings of the   International Display Manufacturing Conference, Taipei, Taiwan , 3-6 July 2007.

K. L. Marshall, V. Rapson, Y. Zhang, G. Mitchell, and A. L. Rigatti, “Contaminant Resistant Sol-Gel Coatings for High Peak Power Laser Applications,” to be published in the Proceedings of the OSA Optical Interference Coatings Conference (OSA-OIC), Tucson, AZ, 3–8 June 2007.

K. L. Marshall, A. Trajkovska-Petkoska, K. Hasman, M. Leitch, G. Cox, T. Z. Kosc, and S. D. Jacobs, “Doped Multilayer Polymer Cholesteric-Liquid-Crystal (PCLC) Flakes: A Novel Electro-Optical Medium for Highly Reflective Color Flexible Displays,” to be published in the Proceedings of the SID 2007 Symposium, Long Beach, CA, 20–25 May 2007.

B. Ashe, K. L. Marshall, C. Giacofei, A. L. Rigatti, T. J. Kessler, A. W. Schmid, J. B. Oliver, J. Keck, and A. Kozlov, “Evaluation of Cleaning Methods for Multilayer Diffraction Gratings,” in Laser-Induced Damage in Optical Materials: 2006 , edited by G. J. Exarhos, A. H. Guenther, K. L. Lewis, D. Ristau, M. J. Soileau, and C. J. Stolz (SPIE, Bellingham, WA, 2007), Vol. 6403, p. 64030O.

M. Haurylau, S. P. Anderson, K. L. Marshall, and P. M. Fauchet, “Electrically Tunable Silicon 2-D Photonic Bandgap Structures,” IEEE J. Quantum Electron. 12 (6), 1527–1533 (2006).

K. L. Marshall, A. G. Noto, G. Painter, and N. Tabirian, “Computational Chemistry Methods for Predicting the Chiroptical Properties of Liquid Crystal Systems. II. Application to Chiral Azobenzenes,” in Liquid Crystals X , edited by I.-C. Khoo (SPIE, Bellingham, WA, 2006), Vol. 6332, p. 63320C.

The Exocuticles of Beetles Contain Layers of Chitin, a Naturally Occurring Polysaccaride that Possesses a Cholesteric Liquid Crystal Structure Jewel Scarab Beetle -National Geographic

Dr. Ansgar Schmid is a Senior Scientist in charge of the Laser Damage Program at LLE. He supervises the operation of three laser damage testing facilities (see below). He conducts basic research to understand the mechanisms underlying initiation of damage in materials and thin films. For his research, Dr. Schmid uses several nano-metrology tools located in the COM/LLE Metrology Laboratory that include:

• A Digital Instruments Nanoscope III Atomic Force Microscope-version 2.2 (AFM) for taking surface topography maps with atomic scale lateral resolution; equipped to perform contact AFM, tapping mode AFM, non-contact AFM, lateral force microscopy (LFM), phase imaging, and nanoindentation at very low loads (Hystron Triboscope).
• A Witec Alpha Scanning Near-field Optical Microscope (SNOM) for studying surfaces with high resolution using scanning near-field optical microscopy, confocal microscopy, and atomic force microscopy in a single instrument.

Dr. Semyon Papernov is a scientist at LLE. He is responsible for operating the conventional laser damage testing facility at LLE. He is also the principal operator of the Digital Instruments Nanoscope III Atomic Force Microscope in the COM Metrology Laboratory. For the past several years, Dr. Papernov has organized and taught a course in AFM theory and techniques to graduate students in Materials Science and Mechanical Engineering.

Dr. Papernov and Dr. Schmid collaborate on fundamental studies of laser damage from extrinsic artifacts in thin films through the introduction of engineered defects.

Laser Damage Testing Facilities:

Conventional Testing Facility, Location: LLE Rm. 135
Status: Operational with high reliability
Description: Frequency-converted, flashlamp-pumped Nd: glass w/ zig-zag slab
l/Pulsewidth: 1w red/1 ns; 2w green/0.8 ns; 3w blue/0.6 ns
Pulse shape: gaussian Rep rate: 8 shots per minute Beam size: 0.6 mm
Methodology: 1-on-1 or N-on-1; damage assessed by dark field microscopy @110x
Applications: 3w/0.6 ns– new HR/AR materials, processes, designs
1w/1.0 ns– high power diffraction grating concepts

Short Pulse Testing Facility, Location: LLE Rm. 132 Status: Operational Description: Positive Light Inc., Ti:sapphire + glass, chirped–pulse @ 50 mJ l/Pulsewidth: 1w red only/0.5 ps to 10 ps; 100 ps possible w/ different compressor Pulse shape: “gaussian” output from compressor
Rep rate: 1 shot per minute (glass rod limited) Beam size: 1 mm Methodology: 1-on-1 or N-on-1; damage assessed by dark field microscopy @110x Applications: HR/AR film designs, beam combiners, off-axis parabolas Diffraction gratings by photopolymerization, (reactive ion-) etching, ion-milling

Shaped Pulse Testing Facility, Location: LLE Rm. 134
Status: Operational
Description: Nd: glass pumped Large Aperture Ring Amplifier for 30 J
l/Pulsewidth: 1w red/1 ns to 3 ns; 3w blue/1 ns to 3 ns (possibly 4-5 ns)
Pulse shape: “square” and “Haan” Rep rate: 1 shot every 20 minutes
Beam size: 16 mm diameter (2-cm²)
Methodology: 1-on-1 or N-on-1 (with N a small number)
inspection/assessment TBD depending on spot size
Applications: 1w/3 ns or longer square pulse - scaling for red transport: HR’s/AR’s
3w/3 ns or longer square pulse - scaling for blue transport: HR’s/AR’s

Recent Publications and Presentations:

S.G. Lukishova, A.W. Schmid, R. Knox, P. Freiwald, L.J. Bissell, R.W. Boyd, C.R. Stroud, and K.L. Marshall, “Room-Temperature Source of Single Photons of Definite Polarization”, J.Mod.Opt. 54 (2-3), 417 – 429 (2007).

S. Papernov and A.W. Schmid, “Using Gold Nanoparticles as Artificial Defects in Thin Films: What Have We Learned About Laser-Induced Damage Driven by Localized Absorbers?”, in Laser-Induced Damage in Optical Materials: 2006 , edited by G.J. Exarhos, A.H. Guenther, K.L. Lewis, D. Ristau, M.J. Soileau, and C.J. Stolz (SPIE, Bellingham, WA, 2007), Vol. 6403, p. 64030D (invited).

Damage crater produced by 351nm pulse in SiO2 thin film doped with 8nm gold particles.

Ms. Amy Rigatti is head of Optics Manufacturing (OMAN) at LLE. She manages the activities of a group of ~25 engineers and technicians who are responsible for the design, acquisition or manufacture, testing, installation, and maintenance of almost all the optics used in OMEGA, the 60 beam Nd: glass laser system at LLE, as well as OMEGA EP (under construction). Amy is also responsible for managing contract work with outside organizations like LLNL in California and CEA in France.

Thin-film coatings are deposited on a range of substrate materials to meet antireflection, reflection, or beam-control requirements at specific angles, wavelengths, and polarizations. Optical coatings must achieve the necessary resistance to laser-induced damage, produce the desired change in spectral and photometric performance, and maintain the surface figure of the finished substrate.

OMAN’s coatings consist of two primary types:

• reactive physical vapor deposition (PVD) of oxides via electron-beam evaporation for all hard coating types, especially those that have complex spectral requirements at multiple angles, wavelengths and polarizations.
• liquid deposition of suspended silica molecules (sol-gel) via spin- or dip-coating techniques for high-performance antireflection coatings, especially in the highest fluence applications.

OMAN maintains clean room facilities for substrate preparation and inspection prior to coating, and for the manufacture of liquid-crystal polarizers and wave plates. The group takes on large-scale research and development challenges for outside customers. Currently, OMAN is responsible for the manufacture and delivery of 1w HR mirrors and polarizers for the National Ignition Facility at LLNL. It is also performing deformable mirror fabrication for NIF.

OMAN has its own laser damage test facility with the following attributes:

Long Pulse Testing Facility (Sparky), Location: Annex Rm. 180
Status: Operational in the red 1w, but not yet in the blue 3w
Description: Spectra-Physics (LLNL) high-rep-rate, flashlamp-pumped YAG
l/Pulsewidth: 1w red/10 ns; 3w blue/6 ns Pulse shape: gaussian
Rep rate: 10 shots per second (operated @ 20 shots per minute) Beam size: 1 mm
Methodology: –1w raster scanning over 50 mm part; damage assessed by dark field microscopy @110x if a spark is detected; lower rep-rate 1-on-1 and N-on-1 modes possible
–3w N-on-1 testing when available
Applications: 1w/10 ns–required for HR and polarizer production QA in support of the National Ignition Facility (NIF) Program at LLNL
3w/6 ns– new HR/AR materials, processes, designs

Recent Publications and Presentations:

B. Ashe, K.L. Marshall, C. Giacofei, A.L. Rigatti, T.J. Kessler, A.W. Schmid, J.B. Oliver. J. Keck, and A. Kozlov, “Evaluation of Cleaning Methods for Multilayer Diffraction Gratings”, in Laser-Induced Damage in Optical Materials: 2006 , edited by G.J. Exarhos, A.H. Guenther, K.L. Lewis, D. Ristau, M.J. Soileau, and C.J. Stolz (SPIE Bellingham, WA, 2007), Vol. 6403, p. 64030O.

OMAN's 54 inch vacuum chamber (background) with an ion-etch capability to produce distributed phase plates.

Recent Publications and Presentations:

S. N. Shafrir, J. C. Lambropoulos and S. D. Jacobs, "Subsurface damage (SSD) and microstructure in precision microground hard ceramics using MRF spots," Applied Optics 46 5500-5515 (Aug. 2007)

S. N. Shafrir, J. C. Lambropoulos, and S. D. Jacobs , “A Magnetorheological Polishing-Based Approach for Studying Precision Microground Surfaces of Tungsten Carbides,” Precision Engineering 31 , 83–93 (2007).

Dr. Tanya Kosc is a scientist in the Materials Group at LLE. She received her PhD from The Institute of Optics at the University of Rochester for research on the mechanism of rotational motion for polymer cholesteric liquid crystal (PCLC) flakes in an external electric field. In AC electric fields of very low amplitude, and over a well-defined frequency regime, Dr. Kosc demonstrated 90 degrees of rotation for 40 µm size flakes in times as short as a few hundred ms. Rotation was accompanied by extremely large changes in reflected light intensity, and the motion was well-controlled.

The application of these flakes as electronic ink in displays is envisioned, since this approach is more easily capable of color than other approaches currently being commercialized (e.g., E-Ink®, Gyricon®).

In addition to continuing her research on PCLC flakes, Dr. Kosc works on the development of instrumentation for the characterization of the laser beamlines in OMEGA.

Recent Publications and Presentations:

T. Z. Kosc, K. L. Marshall, A. Trajkovska-Petkoska, C. J. Coon, K. Hasman, G. V. Babcock, R. Howe, M. Leitch, and S. D. Jacobs, “Development of Polymer Cholesteric Liquid Crystal Flake Technology for Electro-Optic Devices and Particle Displays,” in Emerging Liquid Crystal Technologies II, edited by L.-C. Chien (SPIE, Bellingham, WA, 2007), Vol. 6487, p. 64870L (invited).

T. Z. Kosc, C. J. Coon, G. V. Babcock, K. L. Marshall, A. Trajkovska-Petkoska, and S. D. Jacobs, “Exploring Motion Reversal in Polymer Cholesteric-Liquid-Crystal Devices,” in Liquid Crystals X, edited by I.-C. Khoo (SPIE, Bellingham, WA, 2006), Vol. 6332, p. 633209.

T. Z. Kosc, A. A. Kozlov, and A. W. Schmid, “Formation of Periodic Microstructures on Multilayer Dielectric Gratings Prior to Total Ablation,” Opt. Express 14 (22), 10,921–10,929 (2006).

T. Z. Kosc, "Particle Display Technologies Become Electronic Paper," Optics & Photonics News, pp. 18-23 (Feb., 2005) - cover photo for issue.

Mr. Alexander Maltsev is the supervisor of the LLE Optical Fabrication Shop. As a master optician, he is responsible for carrying out unique manufacturing projects in support of LLE and other University research programs. Mr. Maltsev turns out precision, one-of-a-kind optical elements from specialty glasses and crystals.

Products include prisms, etalons, and other specially shaped optics. He also maintains and operates a large continuous polishing machine used to polish 300 mm diameter flats to l/20 precision.

Every other spring, Mr. Maltsev teaches the laboratory sessions for Optics 443: Optical Fabrication and Testing, a graduate elective offered through The Institute of Optics. In this course, students learn how to hand-fabricate and test precision optics, starting from a glass block.