James Grant-Jacob

Micron-scale copper wires printed using femtosecond laser-induced forward transfer with automated donor replenishment

We demonstrate the use of laser-induced forward transfer (LIFT) in combination with a novel donor replenishment scheme to print continuous copper wires. Wires of mm length, a few microns wide and submicron in height have been printed using a 800 nm, 1 kHz repetition rate, 150 fs pulsed laser. A 120 nm thick copper donor was used along with laser pulse energy densities of 0.16-0.21 J cm−2 to print overlapping few-micron sized pads to form the millimeter long wires. The wires have a measured resistivity of 17 ± 4 times that of bulk copper.

Diode-end-pumped 1.2 W Yb:Y 2 O 3 planar waveguide laser

Fabrication, characterization and laser performance of a Watt-level ytterbium-doped yttria waveguide laser is presented. The waveguide was grown onto a YAG substrate by pulsed laser deposition and features a 6 µm thick ytterbium-doped yttria layer sandwiched between two 3 µm undoped yttria layers. The laser deposited film was characterized by X-ray diffraction, showing a high degree of crystallinity and analyzed spectroscopically, showing performance indistinguishable from previously reported bulk material. When pumped with 8.5 W from a broad area diode laser the waveguide laser produces 1.2 W of output at 1030 nm.

Diode-end-pumped 1.2W Yb:Y2O3 planar waveguide laser

Fabrication, characterization and laser performance of a Watt-level ytterbium-doped yttria waveguide laser is presented. The waveguide was grown onto a YAG substrate by pulsed laser deposition and features a 6 µm thick ytterbium-doped yttria layer sandwiched between two 3 µm undoped yttria layers. The laser deposited film was characterized by X-ray diffraction, showing a high degree of crystallinity and analyzed spectroscopically, showing performance indistinguishable from previously reported bulk material. When pumped with 8.5 W from a broad area diode laser the waveguide laser produces 1.2 W of output at 1030 nm.

An 11.5 W Yb:YAG planar waveguide laser fabricated via pulsed laser deposition

We present details of the homo-epitaxial growth of Yb:YAG onto a oriented YAG substrate by pulsed laser deposition. Material characterization and initial laser experiments are also reported, including the demonstration of laser action from the 15 µm-thick planar waveguide generating 11.5 W of output power with a slope efficiency of 48%. This work indicates that under appropriate conditions, high-quality single-crystal Yb:YAG growth via pulsed laser deposition is achievable with characteristics comparable to those obtained via conventional crystal growth techniques.

456-mW graphene Q-switched Yb:yttria waveguide laser by evanescent-field interaction.

In this Letter, we present a passively Q-switched Yb:Y2O3 waveguide laser using evanescent-field interaction with an atmospheric-pressure-chemical-vapor-deposited graphene saturable absorber. The waveguide, pumped by a broad area diode laser, produced an average output power of 456 mW at an absorbed power of 4.1 W. The corresponding pulse energy and peak power were 330 nJ and 2 W, respectively. No graphene damage was observed, demonstrating the suitability of top-deposited graphene for high-power operation.

Single-pulse multiphoton polymerization of complex structures using a digital multimirror device

We present a rapid technique for the patterning of complex structures with ~2µm resolution via multiphoton polymerization, through use of a single ultrashort pulse in combination with the spatial intensity modulation possible from a digital multimirror device. Sub-micron features have been achieved through the use of ten consecutive pulses.

Dynamic spatial pulse shaping via a digital micromirror device for patterned laser-induced forward transfer of solid polymer films

We present laser-induced forward transfer of solid-phase polymer films, shaped using a Digital Micromirror Device (DMD) as a variable illumination mask. Femtosecond laser pulses with a fluence of 200-380 mJ/cm2 at a wavelength of 800 nm from a Ti:sapphire amplifier were used to reproducibly transfer thin films of poly(methyl methacrylate) as small as ~30 µm by ~30 µm with thickness ~1.3 µm. This first demonstration of DMD-based solid-phase LIFT shows minimum feature sizes of ~10µm.

Pulsed laser deposited diode-pumped 7.4 W Yb:Lu 2 O 3 planar waveguide laser

Fabrication, characterization, and laser performance of an Yb:Lu₂O₃ planar waveguide laser are reported. Pulsed laser deposition was employed to grow an 8 µm-thick Yb-doped lutetia waveguide on a YAG substrate. X-ray diffraction was used to determine the crystallinity, and spectroscopic characterization showed the absorption and emission cross-sections were indistinguishable from those reported for bulk material. When end-pumped by a diode-laser bar an output power of 7.4 W was achieved, limited by the available pump power, at a wavelength of 1033 nm and a slope efficiency of 38% with respect to the absorbed pump power.

Ytterbium-doped-garnet crystal waveguide lasers grown by pulsed laser deposition

The growth of a range of crystal garnets by pulsed laser deposition is presented. As a result of optimization of the fabrication process, films can now be grown with optical quality approaching that of bulk material. To demonstrate this, we present laser performance from a Yb:YAG film with 70% slope efficiency and >16 W of output power. In addition, we present the first pulsed laser deposition of laser quality Yb:GGG and Yb:YGG. Watt-level laser performance is achieved for these two gallium garnets and routes to further performance improvements and potential applications of these films are discussed.

Er:YGG planar waveguides grown by pulsed laser deposition for LIDAR applications

Er:YGG planar waveguide amplifiers (PWAs) are promising candidates to meet the needs of greenhouse-gas differentialabsorption LIDAR applications. We report pulsed–laser-deposition growth of this doped crystal and net-gain performance (internal gain ~2 dB/cm for 0.7-at.% Er-doping) in a 0.9-cm-long uncoated single-pass PWA. Rapid fabrication is also demonstrated with optimized parameters, where crystal growth rates approaching 20 microns/hour have been realized. We compare Er-doping concentrations ranging from 0.5 at.% - 4 at.%, and report on their spectroscopic properties. Furthermore, we show the ability to tailor the deposited crystal properties, controlling the waveguide and gain characteristics. Finally, we discuss the spectroscopy and potential performance of this relatively unstudied material for PWAs in the eye-safe regime.