Marc Nantel

Bio: Marc Nantel is an academic researcher from University of Toronto. The author has contributed to research in topics: Laser & Ultrashort pulse. The author has an hindex of 4, co-authored 10 publications receiving 27 citations.

Advanced-laser processing of photonic and microelectronic components at Photonics Research Ontario

Abstract: Photonics Research Ontario (PRO) is an Ontario Provincial Center of Excellence supporting a broad range of laser- processing activities within its photonics program. These activities are centered at the University of Toronto, and split between an industrial-user facility and the individual research programs of principal investors. The combined effort furnishes forefront laser system and advanced optical tools to explore novel processing applications in photonic, biomedical, and microelectronic areas. Facilities include laser micromachining stations, excimer-based mask-projection stations, extremely short wavelength lasers such as the molecular fluorine laser, and ultrafast laser systems. The latter two advanced laser offer interesting advantages and contrast in processing 'difficult' materials through linear and nonlinear absorption processes, respectively. These laser systems provide fine precision and strong interaction with a wide range of materials, including 'transparent' glasses, and also ceramics and metals. Applications fall broadly into several areas: wafer-level circuit trimming, high-resolution ultrasonic transducers, and the shaping of optical waveguides and Bragg-gratings for photonic components. This paper summarizes the laser-processing infrastructure and research activities at PRO.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The effects of degraded spatial coherence on ultrafast-laser channel etching.

Abstract: When laser-etching channels through solid targets, the etch-rate is known to decrease with increasing depth, partly because of absorption at the sides of the channel. For ultrafast-laser pulses at repetition rates >100MHz, we show that the etch-rate is also affected by optical properties of the beam: the channel acts as a waveguide, and so the pulses will decompose into dispersive normal modes. Additionally, plasma on the inner surface of the channel will cause scattering of the beam. These effects will cause a loss of spatial coherence in the pulse, which will affect the propagated intensity distribution and ultimately the etch-rate. We have characterized this effect for various foil thicknesses to determine the evolution of the beam while drilling through metal.

Single-pulse and 'pulsetrain-burst'(>100 MHz) effects in ultrafast laser processing of metals, glasses, and bio-tissues

Abstract: Studies contrasting low (1 kHz) and high (>100 MHz) repetition rate approaches to ultrafast laser material processing present new means for minimizing damage and increasing processing speed in excising microholes in metals, glasses, and -hard and soft- bio-tissues.

Transverse coherence measurement using a folded Michelson interferometer.

Abstract: The transverse coherence of a 1 ps pulsed laser beam was measured using a technique involving a modified Michelson interferometer and separate reference images. Using this technique, the transverse coherence of a selected plane in the laser beam was determined, in this case at the exit of a channel in a metal foil self-drilled by the laser. Images of each arm were used as references. Through this technique, it is possible to use the interference patterns produced with uneven intensity distributions and for pulsed lasers on a single-shot basis. The results of these measurements were then shown to be in agreement with those obtained using a Young's double-slit setup.

Optical coherence and beamspread in ultrafast-laser pulsetrain-burst hole drilling

Abstract: Pulsetrain-burst machining has been shown to have advantages over single-pulse laser processing of materials and biological tissues. Ultrafast lasers are often able to drill holes in brittle and other difficult materials without cracking or swelling the target material, as is sometimes the case for nanosecond-pulse ablation; further, pulsetrain-bursts of ultrafast pulses are able to recondition the material during processing for instance, making brittle materials more ductile and striking advantages can result. In the work we report, we have investigated hole-drilling characteristics in metal and glass, using a Nd:glass pulsetrain-burst laser (1054 nm) delivering 1-10 ps pulses at 133 MHz, with trains 3-15 μs long. We show that as the beam propagates down the channel being drilled, the beam loses transverse coherence, and that this affects the etch-rate and characteristics of channel shape: as the original Gaussian beam travels into the channel, new boundary conditions are imposed on the propagating beam principally the boundary conditions of a cylindrical channel, and also the effects of plasma generated at the walls as the aluminum is ablated. As a result, the beam will decompose over the dispersive waveguide modes, and this will affect the transverse coherence of the beam as it propagates, ultimately limiting the maximum depth that laser-etching can reach. To measure transverse beam coherence, we use a Youngs two-slit interference setup. By measuring the fringe visibility for various slit separations, we can extract the transverse coherence as a function of displacement across the beam. However, this requires many data runs for different slit separations. Our solution to this problem is a novel approach to transverse coherence measurements: a modified Michelson interferometer. Flipping the beam left-right on one arm, we can interfere the beam with its own mirror-image and characterise the transverse coherence across the beam in a single shot.

Femtosecond laser processing system with process parameters, controls and feedback

Abstract: A femtosecond laser based laser processing system having a femtosecond laser, frequency conversion optics, beam manipulation optics, target motion control, processing chamber, diagnostic systems and system control modules. The femtosecond laser based laser processing system allows for the utilization of the unique heat control in micromachining, and the system has greater output beam stability, continuously variable repetition rate and unique temporal beam shaping capabilities.

High frequency array ultrasound system

Abstract: A system for acquiring an ultrasound signal comprises a signal processing unit adapted for acquiring a received ultrasound signal from an ultrasound transducer having a plurality of elements. The system is adapted to receive ultrasound signals having a frequency of at least 20 megahertz (MHz) with a transducer having a field of view of at least 5.0 millimeters (mm) at a frame rate of at least 20 frames per second (fps). The signal processing can further produce an ultrasound image from the acquired ultrasound signal. The transducer can be a linear array transducer, a phased array transducer, a two-dimensional (2-D) array transducer, or a curved array transducer.

Arrayed ultrasonic transducer

Abstract: An ultrasonic transducer comprises a stack having a first face, an opposed second face and a longitudinal axis extending therebetween. The stack comprises a plurality of layers, each layer having a top surface and an opposed bottom surface, wherein the plurality of layers of the stack comprises a piezoelectric layer and a dielectric layer. The dielectric layer is connected to the piezoelectric layer and defines an opening extending a second predetermined length in a direction substantially parallel to the axis of the stack. A plurality of first kerf slots are defined therein the stack, each first kerf slot extending a predetermined depth therein the stack and a first predetermined length in a direction substantially parallel to the axis. The first predetermined length of each first kerf slot is at least as long as the second predetermined length of the opening defined by the dielectric layer and is shorter than the longitudinal distance between the first face and the opposed second face of the stack in a lengthwise direction substantially parallel to the axis.

The interferometer patterns due to the primary aberrations

Abstract: In order to obtain a rapid estimate of the quality of a lens by observing its behaviour in the interferometer, it is necessary for the observer to be familiar with the characteristic patterns of the various primary aberrations under various conditions of adjustment. A method is described by which these patterns can be easily calculated for any required case; and series of typical patterns are shown together with actual interferograms for comparison.