Dong-Jin Won

Microstructured optical fibers as high-pressure microfluidic reactors

Deposition of semiconductors and metals from chemical precursors onto planar substrates is a well-developed science and technology for microelectronics. Optical fibers are an established platform for both communications technology and fundamental research in photonics. Here, we describe a hybrid technology that integrates key aspects of both engineering disciplines, demonstrating the fabrication of tubes, solid nanowires, coaxial heterojunctions, and longitudinally patterned structures composed of metals, single-crystal semiconductors, and polycrystalline elemental or compound semiconductors within microstructured silica optical fibers. Because the optical fibers are constructed and the functional materials are chemically deposited in distinct and independent steps, the full design flexibilities of both platforms can now be exploited simultaneously for fiber-integrated optoelectronic materials and devices.

All-optical modulation of laser light in amorphous silicon-filled microstructured optical fibers

Amorphous silicon is deposited within optical fibers by a high pressure microfluidic deposition process and characterized via Raman spectroscopy. All-optical modulation of 1.55 µm light guided through the silicon core is demonstrated using the free carrier absorption generated by a 532 nm pump pulse. Modulation depths of up to 8.26 dB and modulation frequencies of up to 1.4 MHz are demonstrated.

Deposition of electronic materials inside microstructured optical fibres for novel device applications

Functional materials such as bulk crystalline semiconductor structures inside MOF waveguides could lead to fibre devices with radically new electronic and photonic degrees of freedom. We report the growth of such materials inside MOF templates via a novel microfluidic high pressure chemical vapour deposition technique.

High pressure CVD inside microstructured optical fibres

We report the fabrication of semiconductor structures within holey fibres via a pressure driven microfluidic chemical vapour deposition process, demonstrating templated growth of crystalline Group IV semiconductor structures and devices in extreme aspect ratio geometries.

Microstructured Optical Fibers as New Nanotemplates for High Pressure CVD

Solid state chemists have long been interested in templated growth of materials using many approaches. The resulting materials have been useful in areas as diverse as photonics and catalysis. Microstructured optical fibers (MOFs) form a new class of nanotemplates that can have sub 20 nm pores that are meters to kilometers long. We have developed a high-pressure microfluidic chemical process that allows for conformal deposition of materials within MOFs to form the most extreme aspect ratio semiconductor nanowires known. The wires can be spatially organized with respect to each other at dimensions down to the nanoscale because the MOF templates can be designed with almost any desired periodic or aperiodic pattern. Many if not most of the chemistries used for conventional chemical vapor deposition (CVD) can be adapted for this process. The resulting materials should enable a large range of scientific and technological applications.

Microstructured optical fibre semiconductor metamaterials

We have synthesised arrays of semiconductor wires and tubes inside microstructured optical fibres. These extreme aspect ratio structures have highly functional optoelectronic properties and initial characterisation studies of their waveguiding properties are presented here.

Fabrication of extreme aspect ratio wires within photonic crystal fibers

We have recently fabricated continuous semiconducting micro and nanowires within the empty spaces of highly ordered microstructured (e.g., photonic crystal or holey) optical fibers (MOFs). These systems contain the highest aspect ratio semiconductor micro- and nanowires yet produced by any method: centimeters long and ~100 nm in diameter. These structures combine the flexible light guiding capabilities of an optical fiber with the electronic and optical functionalities of semiconductors and have many potential applications for in-fiber sensing, including in-fiber detection, modulation, and generation of light.