Brian D'Urso

Graphene Q-Switched Mode-Locked and Q-Switched Ion-Exchanged Waveguide Lasers

In this letter, we present the use of monolayer graphene saturable absorbers to produce Q-switched and Q-switched mode-locked operation of Yb and Yb:Er-doped phosphate glass waveguide lasers, respectively. For the 1535-nm-wavelength Yb:Er laser, the Q-switched pulses have repetition rates up to 526 kHz and contain mode-locked pulses at a repetition frequency of 6.8 GHz. The measured 0.44-nm bandwidth should allow pulses as short as ~6 ps to be generated. Maximum average output powers of 27 mW are obtained at a slope efficiency of 5% in this mode of operation. For the 1057-nm-wavelength Yb laser, Q-switched pulses are obtained with a repetition rate of up to 833 kHz and a maximum average output power of 21 mW. The pulse duration is found to decrease from 292 to 140 ns and the pulse energy increase from 17 to 27 nJ as the incident pump power increases from 220 to 652 mW.

Q-switched operation of a pulsed-laser-deposited Yb:Y 2 O 3 waveguide using graphene as a saturable absorber

The first, to the best of our knowledge, Q-switched operation of a pulsed-laser-deposited waveguide laser is presented. A clad Yb:Y(2)O(3) waveguide was Q-switched using an output coupling mirror coated with a single layer of graphene deposited by atmospheric pressure chemical vapor deposition. During continuous-wave operation, a maximum power of 83 mW at a slope efficiency of 25% was obtained. During Q-switched operation, pulses as short as 98 ns were obtained at a repetition rate of 1.04 MHz and a central wavelength of 1030.8 nm.

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.

Wetting states on structured immiscible liquid coated surfaces

Water on structured hydrophobic surfaces can be supported in a Wenzel or Cassie state, depending on surface chemistry and structure geometry. The Cassie state is often desirable for superhydrophobic materials as it features high contact angles and low contact angle hysteresis due to an air layer which separates most of the liquid from contact with the solid. We present evidence that multiple wetting states for water can also exist on multiscale structured surfaces with a layer of an immiscible liquid coating the surface and that a Cassie-like state can be achieved which results in enhancement of the surface properties.

Quantum measurements between a single spin and a torsional nanomechanical resonator

While the motions of macroscopic objects must ultimately be governed by quantum mechanics, the distinctive features of quantum mechanics can be hidden or washed out by thermal excitations and coupling to the environment. We propose a system consisting of a graphene nanomechanical oscillator (NMO) coupled with a single spin through a uniform external magnetic field, which could become the building block for a wide range of quantum nanomechanical devices. The choice of graphene as the NMO material is critical for minimizing the moment of inertia of the oscillator. The spin originates from a nitrogen-vacancy (NV) center in a diamond nanocrystal that is positioned on the NMO. This coupling results in quantum non-demolition (QND) measurements of the oscillator and spin states, enabling a bridge between the quantum and classical worlds for a simple readout of the NV center spin and observation of the discrete states of the NMO.

Room-Temperature Quantum Transport Signatures in Graphene/LaAlO3/SrTiO3 Heterostructures

High mobility graphene field-effect devices, fabricated on the complex-oxide heterostructure LaAlO3 /SrTiO3 , exhibit quantum interference signatures up to room temperature. The oxide material is believed to play a critical role in suppressing short-range and phonon contributions to scattering. The ability to maintain pseudospin coherence at room temperature holds promise for the realization of new classical and quantum information technologies.

Ultra-Precision Machining of Stainless Steel and Nickel with Single Crystal 4H and 6H Boule SiC

Ultra-precision machining is dominated by single-crystal diamond cutting tools, and is typically applied to a narrow range of materials, particularly aluminum and copper. Single-crystal SiC can be comparable to some diamonds in hardness and thermal conductivity, while potentially having superior chemical and thermal stability, yet it has not been explored as a cutting tool for ultra-precision machining. We made two cutting tools with single-crystal SiC, one with sharp corners and one with a large circular radius, and used them to cut flat surfaces on two materials, 316 stainless steel and nickel. These materials generally cause unacceptably rapid diamond tool wear. We report the average roughness of the resulting surfaces cut with single-crystal 4H and 6H SiC tools.

Design and construction of a cost-efficient Arduino-based mirror galvanometer system for scanning optical microscopy

Mirror galvanometer systems (galvos) are commonly employed in research and commercial applications in areas involving laser imaging, laser machining, laser-light shows, and others. Here, we present a robust, moderate-speed, and cost-efficient home-built galvo system. The mechanical part of this design consists of one mirror, which is tilted around two axes with multiple surface transducers. We demonstrate the ability of this galvo by scanning the mirror using a computer, via a custom driver circuit. The performance of the galvo, including scan range, noise, linearity, and scan speed, is characterized. As an application, we show that this galvo system can be used in a confocal scanning microscopy system.