Peter R. Herman

University of Toronto

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Jianzhao Li

Xidian University

Shane M. Eaton

Center for Biomolecular Nanotechnologies

Stephen Ho

University of Toronto

Moez Haque

University of Toronto

J. S. Aitchison

University of Toronto

Mi Li Ng

OZ Optics (Canada)

Haibin Zhang

Xi'an Jiaotong University

Jason R. Grenier

Corning (United States)

Abdullah Rahnama

University of Toronto

Luís A. Fernandes

OZ Optics (Canada)

Cooperative Institutions

University of Toronto

192

Osaka University

National Research Council Canada

Centre National de la Recherche Scientifique

National Academies of Sciences, Engineering, and Medicine

Rutherford Appleton Laboratory

University Health Network

Occupational Cancer Research Centre

University of New Brunswick

Institute for Laser Technology

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Laser Scanning Holographic Lithography for Flexible 3D Fabrication of Multi-Scale Integrated Nano-structures and Optical Biosensors

Scientific Reports (2016)

Yuan Liang Peter R. Herman

Abstract Three-dimensional (3D) periodic nanostructures underpin a promising research direction on the frontiers of nanoscience and technology to generate advanced materials for exploiting novel photonic crystal (PC) and nanofluidic functionalities. However, formation of uniform and defect-free 3D periodic structures over large areas that can further integrate into multifunctional devices has remained a major challenge. Here, we introduce a laser scanning holographic method for 3D exposure in thick photoresist that combines the unique advantages of large area 3D holographic interference lithography (HIL) with the flexible patterning of laser direct writing to form both micro- and nano-structures in a single exposure step. Phase mask interference patterns accumulated over multiple overlapping scans are shown to stitch seamlessly and form uniform 3D nanostructure with beam size scaled to small 200 μm diameter. In this way, laser scanning is presented as a facile means to embed 3D PC structure within microfluidic channels for integration into an optofluidic lab-on-chip, demonstrating a new laser HIL writing approach for creating multi-scale integrated microsystems.

Photoresist

Laser Scanning

Interference lithography

Embossing

Maskless lithography

10.1038/srep22294

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Citations (43)

Photosensitization of standard fibers with deep uv laser radiation

Journal of Lightwave Technology (2003)

K.P. Chen Peter R. Herman

A strong and permanent ultraviolet photosensitivity enhancement was locked into standard optical fiber pre-treated with above-bandgap 157-nm F ₂ -laser radiation. Below-bandgap 248-nm irradiation of the pre-treated fiber yielded fiber Bragg gratings (FBGs) with an index contrast of 6.5 × 10/sup -4/, a value four-fold larger than that available in 16% Ge-doped photosensitive fiber. The F ₂ -laser photosensitivity locking was 300 times more effective than with KrF-laser pre-treatment in terms of the accumulated fluence required to lock in a similar refractive index change. Accelerated FBG aging tests equivalent to 25 years at 70°C revealed a less than 2% reflectivity decay in both 157- and 248-nm pre-treated fibers, which is sufficient to eliminate the postannealing step typically required in hydrogen-loaded fibers. The large photosensitization and the superior thermal stability of both 248- and 157-nm pre-treated fibers are associated with a new Si-H bond absorption feature at 1387 nm, which appears only during the FBG formation step.

Photosensitivity

Ultraviolet

Fiber Bragg Grating

10.1109/jlt.2003.815643

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Citations (17)

<title>Extreme-ultraviolet laser photo-pumped by a self-healing Hg target</title>

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (1994)

Hideo Yamakoshi Chien Ting Chin Sebastian Jaimungal Peter R. Herman F. W. Budnik

A self-healing target has been demonstrated for synchronous photo-pumping of extreme- ultraviolet lasers. The threaded, mercury-wetted copper rod, rotating in a pool of mercury, offers similar photoionization efficiency as gold targets, but without target-surface degradation. A gain coefficient of 1.4 cm^-1 was obtained with mercury for the 1089 angstrom Xe²⁺ laser at a pump-laser intensity of 140 GW(DOT)cm^-2, comparing favorably with results from gold targets.

Mercury

Ultraviolet

Extreme ultraviolet

Angstrom

Optical Pumping

10.1117/12.168003

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Citations (3)

Laser machining of micro-lenses on the end face of single-mode optical fibers

Applied Physics A (2008)

Henri Dou J. Li Peter R. Herman J.S. Aitchison Thomas Fricke-Begemann

Laser beam machining

Laser Ablation

10.1007/s00339-008-4425-2

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Citations (22)

Femtosecond filaments for rapid and flexible writing of Fiber-Bragg grating (Conference Presentation)

Erden Ertorer Moez Haque Jianzhao Li Peter R. Herman

Kerr-lens self-channelling of femtosecond laser light offers a novel high-aspect geometry for laser processing inside transparent materials. In glass materials, the laser filaments enable white-light continuum generation, scribing, nanochannel formation, and refractive index modification. In the present work, refractive index matching oils were applied around optical fiber to eliminate astigmatic aberration and thereby form highly symmetric and uniform filaments selectively in the cladding or core waveguide of standard single-mode optical fibre (SMF-28). Under tight focusing, long filaments exceeding 20 um length were formed with single pulses to sub-micron diameter. Arrays of 0.5 um spaced filaments are verified by formation of strong fiber Bragg gratings (FBGs). Flexible positioning of the filament arrays within the fiber core offers wide scope for coupling to cladding and radiation modes and creating new types of in-fibre optical devices.

Cladding (metalworking)

PHOSFOS

Fiber Bragg Grating

10.1117/12.2257545

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Citations (0)

Femtosecond laser direct fabrication of integrated optical wave plates in fused silica

Luís A. Fernandes Jason R. Grenier Jin Hee Kim Peter R. Herman J. S. Aitchison

Femtosecond laser fabrication of optical waveguides in bulk silica glass is extended to integrated optical waveplates. Polarization retardation was controlled by laser exposure, providing for trimming of waveguide birefringence between 10−5 and 10−4.

Trimming

Waveguide

Optical glass

Silica glass

10.1364/cleo_si.2011.cwo6

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A spectroscopic comparison of femtosecond-laser-modified fused silica using kilohertz and megahertz laser systems

Journal of Applied Physics (2006)

Wilbur J. Reichman Denise M. Krol Lawrence Shah Fumiyo Yoshino Alan Arai

Waveguides were written in fused silica using both a femtosecond fiber laser with a 1MHz pulse repetition rate and a femtosecond amplified Ti:sapphire laser with a 1kHz repetition rate. Confocal Raman and fluorescence microscopies were used to study structural changes in the waveguides written with both systems. A broad fluorescence band, centered at 650nm, associated with nonbridging oxygen hole center (NBOHC) defects was observed after waveguide fabrication with the megahertz laser. With the kilohertz laser system these defects were only observed for pulse energies above 1μJ. Far fewer NBOHC defects were formed with the megahertz laser than with kilohertz writing, possibly due to thermal annealing driven by heat accumulation effects at 1MHz. When the kilohertz laser was used with pulse energies below 1μJ, the predominant fluorescence was centered at 550nm, a band assigned to the presence of silicon clusters (Eδ′). We also observed an increase in the intensity of the 605cm−1 Raman peak relative to the total Raman intensity, corresponding to an increase in the concentration of three-membered rings in the lines fabricated with both laser systems.

10.1063/1.2207556

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Citations (52)

F2 -laser photosensitivity applications in germanosilicate fiber and planar waveguides

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2002)

Kevin P. Chen Peter R. Herman Dragan Ćorić Jianzhao Li Xiaoli M. Wei

The energetic 7.9-eV photons of the F₂ laser directly access bandgap states in germanosilicate glasses to provide a strong and direct channel for inducing refractive index changes in optical fibers and planar waveguides. In this paper, we review our F₂-laser photosensitivity studies with an aim to assess prospects for shaping useful photonics structures directly inside the germanosilicate waveguides. We describe strong photosensitivity responses in standard telecommunication fibers and planar optical waveguides without the need for hydrogen loading, and compare with responses provided by traditional ultraviolet lasers. Because of the strong 157-nm absorption in the germanium-doped guiding layers, large non-uniform changes to refractive index are noted that offer opportunities for trimming phase errors and correcting waveguide birefringence in planar optical circuits. With hydrogen soaking, modest 157-nm pre-irradiation was found to 'lock-in' a permanent photosensitivity enhancement in the germanosilicate guiding core, permitting the formation of strong (40-dB) and stable fiber Bragg gratings with 248-nm KrF laser light. The 157-nm 'lock-in' mechanism is associated with Si-OH and Ge-OH defect formation and permanently enhances the ultraviolet photosensitivity response by several orders of magnitude above that for an untreated fiber without the aging related disadvantages of conventional hydrogen soaking. The unique opportunities for F₂-laser photosensitivity applications in shaping and trimming photonic components will be outlined in this presentation.

Photosensitivity

Ultraviolet

Waveguide

10.1117/12.433297

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Citations (3)

Phase-error correction and birefringence control in planar lightwave circuits using photosensitivity locking

K.R. Chen Peter R. Herman

Summary from only given. We apply photosensitivity locking to both stabilize and enhance the photosensitivity responses in planar lightwave circuits (PLCs). Strong photosensitivity was locked in hydrogen-loaded PLCs, and shown to survive thermal annealing at 225C. An index change exceeding 2.5 X 10/sup -3/ and a birefringence of more than 1 X 10/sup -4/ were induced by post laser trimming of a Mach-Zehnder interferometer and an interleaver. The procedure has advantages for phase error correction and birefringence control in PLCs.

Photosensitivity

10.1109/cleo.2002.1033476

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Citations (0)

Femtosecond laser writing of waveguide retarders in fused silica for polarization control in optical circuits

Optics Express (2011)

Luís A. Fernandes Jason R. Grenier Peter R. Herman J. S. Aitchison P. V. S. Marques

Femtosecond laser (300 fs, 500 kHz, 522 nm) fabrication of optical waveguides in bulk silica glass is extended to waveguide retarders. We study the merits of nanograting orientation (perpendicular or parallel to the waveguide) for generating high and low birefringence waveguides. This is used together with other exposure condition to control the waveguide birefringence between 10⁻⁵ and 10⁻⁴ permitting for the simultaneous fabrication of the waveguides and the tuning of the retardance demonstrating quarter and half-wave retarders in the 1200 nm to 1700 nm spectrum. The wavelength dependence of the birefringence is also characterized over a range of exposure conditions.

Waveguide

10.1364/oe.19.018294

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Citations (57)