Shane Huntington

Fabrication of Ultrathin Single-Crystal Diamond Membranes†

A method for preparing ultrathin single-crystal diamond membranes suitable for post-processing and liftout, is reported. The proposed method used single-crystal diamond substrates and two-energy ion implant process for the fabrication of thin diamond membranes. Two ion-implant process was used in this method to prepare two different damage layers within diamond sample. This method can be used for preparing integrated quantum-photonic structure based on color center in diamond. This method can also be used for fabricating various structures including Bragg gratings and whispering gallery mode resonators. A significant application of the diamond nanostructures is to fabricate the micro- and nanoscale cantilevers. It was also observed that the fabricated single-crystal diamond are suitable for another FIB processing.

Diamond waveguides fabricated by reactive ion etching

We demonstrate for the first time the feasibility of all-diamond integrated optic devices over large areas using a combination of photolithography, reactive ion etching (RIE) and focused ion beam (FIB) techniques. We confirm the viability of this scalable process by demonstrating guidance in a two-moded ridge waveguide in type 1b single crystal diamond. This opens the door to the fabrication of a diamond-based optical chip integrating functional elements such as X-crossings, Y-junctions, evanescent couplers, Bragg reflectors/couplers and various interferometers.

Characterization of three-dimensional microstructures in single-crystal diamond

We report on the Raman and photoluminescence characterization of three-dimensional microstructures fabricated in single crystal diamond with a Focused Ion Beam (FIB) assisted lift-off technique. The fabrication method is based on MeV ion implantation, followed by FIB micropatterning and selective chemical etching. In a previous publication we reported on the fabrication of a micro-bridge structure exhibiting waveguiding behavior [P. Olivero, S. Rubanov, P. Reichart, B. Gibson, S. Huntington, J. Rabeau, Andrew D. Greentree, J. Salzman, D. Moore, D. N. Jamieson, S. Prawer, Adv. Mater., 17 (20) (2005) 2427]. In the present work, Raman and photoluminescence spectroscopies are employed to characterize the structural quality of such microstructures, particularly as regards the removal of residual damage created during the machining process. Three-dimensional microstructures in high quality single crystal diamond have many applications, ranging from integrated quantum-optical devices to micro-electromechanical assemblies.

Refractive-index profiling of optical fibers with axial symmetry by use of quantitative phase microscopy

The application of quantitative phase microscopy to refractive-index profiling of optical fibers is demonstrated. Phase images of axially symmetric optical fibers immersed in index-matching fluid are obtained, and the inverse Abel transform is used to obtain the radial refractive-index profile. This technique is straightforward, nondestructive, repeatable, and accurate. Excellent agreement, to within approximately 0.0005, between this method and the index profile obtained with a commercial profiler is obtained.

Raman study on the speciation of copper cyanide complexes in highly saline solutions

Abstract Previous studies have established that the following three copper(I)-cyanide complexes form in aqueous solution: [Cu(CN) 2 ] − , [Cu(CN) 3 ] 2− and [Cu(CN) 4 ] 3− . The distribution of these complexes in solution at equilibrium is highly dependent upon the CN/Cu molar ratio. The speciation of copper cyanide complexes in highly saline solutions is of interest to Australian mining companies because of the unusually highly saline process water used on the goldfields of Western Australia (ca. 200 g/l total dissolved solids). This study has used the vibrational technique of Raman spectroscopy to determine the effect of highly saline water on the equilibrium distribution of copper cyanide complexes in solution for various CN/Cu molar ratios. For the first time it has been shown that in highly saline solutions the equilibrium distribution of copper cyanide complexes changes significantly. It has been established that [Cu(CN) 3 ] 2− predominantly forms in highly saline solutions for CN/Cu molar ratios of 2.2 to 2.5, where previously it has been shown that both [Cu(CN) 2 ] − and [Cu(CN) 3 ] 2− exist in non-saline solutions. Furthermore, in saline solutions containing an excess of cyanide (ca. 200 mg/l) only [Cu(CN) 4 ] 3− exists in solution and the formation of [Cu(CN) 3 ] 2− has not been observed. This phenomenon has been used to explain the increased selectivity of ion exchange resins for gold cyanide in highly saline solutions.

Micromachining structured optical fibers using focused ion beam milling

A focused ion beam is used to mill side holes in air-silica structured fibers. By way of example, side holes are introduced in two types of air-structured fiber, (1) a photonic crystal four-ring fiber and (2) a six-hole single-ring step-index structured fiber.

Critical components for diamond-based quantum coherent devices

The necessary elements for practical devices exploiting quantum coherence in diamond materials are summarized, and progress towards their realization documented. A brief review of future prospects for diamond-based devices is also provided.

Nano-manipulation of diamond-based single photon sources

The ability to manipulate nano-particles at the nano-scale is critical for the development of active quantum systems. This paper presents a technique to manipulate diamond nano-crystals at the nano-scale using a scanning electron microscope, nano-manipulator and custom tapered optical fibre probes. The manipulation of a approximately 300 nm diamond crystal, containing a single nitrogen-vacancy centre, onto the endface of an optical fibre is demonstrated. The emission properties of the single photon source post manipulation are in excellent agreement with those observed on the original substrate.

Refractive index profiling of axially symmetric optical fibers: a new technique

We present a new technique for determining the refractive index profiles of axially symmetric optical fibers based on imaging phase gradients introduced into a transmitted optical field by a fiber sample. An image of the phase gradients within the field is obtained using a new non-interferometric technique based on bright field microscopy. This provides sufficient information to reconstruct the refractive index profile using the inverse Abel transform. The technique is robust, rapid and possesses high spatial resolution and we demonstrate its application to the reconstruction of the refractive index profiles of a single-mode and a multimode optical fiber.

Diamond chemical-vapor deposition on optical fibers for fluorescence waveguiding

A technique has been developed for depositing diamond crystals on the endfaces of optical fibers and capturing the fluorescence generated by optically active defects in diamond into the fiber. This letter details the diamond growth on optical fibers and transmission of fluorescence through the fiber from the nitrogen-vacancy color center in diamond. Control of the concentration of defects incorporated during the chemical vapor deposition growth process is also demonstrated. These are critical steps in developing a fiber coupled single-photon source based on optically active defect centers in diamond.