Day 1 :
Northwestern University, USA
Keynote: Recent advances of III-V semiconductor quantum devices from deep uv ( 200 nm) to thz (300 microns)
Time : 09:00-09:25
Manijeh Razeghi joined Northwestern University, Evanston, IL, as a Walter P. Murphy Professor and Director of the Center for Quantum Devices in fall 1991, where she created the undergraduate and graduate program in solid-state engineering. She is one of the leading scientists in the field of semiconductor science and technology, pioneering in the development and implementation of major modern epitaxial techniques. Her current research interest is in nanoscale optoelectronic quantum devices. She has authored or coauthored more than 1000 papers, more than 30 book chapters, and 16 books. She holds 30 U.S. patents and has given more than 1000 invited and plenary talks. She received the IBM Europe Science and Technology Prize in 1987, the Achievement Award from the SWE in 1995, the R.F. Bunshah Award in 2004 and many best paper awards. Razeghi is an elected fellow of SWE (1995), SPIE (2000), IEC (2003), OSA (2004), APS (2004), IOP (2005), IEEE (2005) and MRS (2008).
Nature offers us different kinds of atoms. But it takes human intelligence to put different atoms together in an elegant way in order to realize manmade structures that is lacking in nature. This is especially true in III-V semiconductor material systems. Guided by highly accurate atomic band structure simulation, modern semiconductor optoelectronic devices are literally made atom by atom using advanced growth technology such as Molecular Beam Epitaxy (MBE) and Metal Organic Chemical Vapor Deposition (MOCVD). Recent breakthroughs have brought such quantum engineering to an unprecedented level, covering an extremely wide spectral range from 200 nm to 300 µm. On the short wavelength side of the electromagnetic spectrum, we have demonstrated III-nitride light emitting diode emitting in deep ultraviolet to visible. In the infrared, quantum cascade lasers (QCLs), and focal plane arrays (FPAs) based on quantum-dot (QD) or type-II superlattice (T2SL) are becoming the choice of technology in crucial applications such as environmental monitoring and space exploration. Last but not the least, on the far-infrared side of the electromagnetic spectrum, also known as the terahertz (THz) region, III-V semiconductor offers a unique solution of generating THz waves in a compact device at room temperature. Continuous effort is being devoted to all of the above mentioned areas with the intention to develop smart technologies that meets the current challenges in environment, health, security, and energy. In this talk, the latest advances in III-V semiconductor optoelectronic devices at the Center for Quantum Devices, Northwestern University, will be presented.
Lancaster University, UK
Time : 09:25-09:50
Tony Krier is professor of physics at Lancaster University where he is director of the Quantum Technology Centre. He obtained his PhD in 1983 and joined Lancaster in 1989, where he founded the mid-infrared optoelectronics research group. He was promoted to Reader in 1999, then to Professor in 2003 and has published more than 190 papers. He has worked extensively on mid-infrared (2-5 μm) materials and devices and in 1996 he founded the international mid-infrared materials & devices conference (MIOMD). His recent work concerns antimonide nanostructures and dilute nitride alloys for use in mid-infrared lasers, photodetectors and solar cells.
The mid-infrared spectral range is technologically important for a variety of applications including gas sensing, optical spectroscopy, bio-medical diagnostics etc. Although InSb QDs have shown electroluminescence up to room temperature and are a promising candidate for diode lasers at wavelengths longer than 3 µm, there have been only a few reports of InSb QD lasers. In this work, we demonstrate coherent emission from InSb QDs at wavelengths between 3.02 µm and 3.11 µm at temperature, Tmax up to 120 K using pulsed excitation, with a threshold current density, Jth~1.6 kA cm-2 at 4 K. The gain and spectral tuning behaviour were also investigated. We developed a hybrid laser structure containing ten sheets of sub-monolayer InSb QDs in an InAs waveguide sandwiched between a p-InAs0.61Sb0.13P0.26 lower cladding layer grown by liquid phase epitaxy and an n+ -InAs plasmonic upper cladding layer grown by MBE. The laser peak blue shifts with increasing temperature when T<50 K. For T>50 K, the peak moves to longer wavelength as temperature increases. The modal gain of the laser was extracted from lasers with different cavity lengths resulting in a value of 29 cm-1, (or 2.9 cm-1 per InSb QD layer), which is close to that found in type II QW lasers emitting at similar wavelengths. The material gain was estimated to be 19 x104 cm-1, which is similar to that for type I QDs.
University of North Carolina at Charlotte, USA
Time : 09:50-10:15
Michael Fiddy received his Ph.D from the University of London, and was faculty member in Physics at Kings College London from 1979-1987. He moved to the University of Massachusetts Lowell in 1987 where he was ECE Department Head from 1994 until 2001. In January 2002 he was appointed the founding director of the Center for Optoelectronics and Optical Communications at UNC Charlotte and since 2011 has been site director for the NSF Industry/University Center for Metamaterials. He is a fellow of the OSA, IOP and SPIE and serves on the OSA Board of Directors.
Depending on material properties, size and shape, one can manage light-matter interactions, scattering phenomena and exploit resonant responses. More complex scattering units or metaatoms provide the opportunity to realize bulk materials with unusual electromagnetic properties. In this talk we investigate the role of local resonances and the effect of some degree of disorder of the meta-atoms on bulk material properties. Coupling between subwavelength elements can result in very large field enhancements and index values not predicted by an effective medium model. Similarly we describe some of the consequences of subwavelength periodicity of these elements and their role in defining bulk material properties. The consequences of disorder and coupling in metamaterial structures sets limits on the material response due to phase decoherence. One can draw parallels with the random phase approximation (RPA) which is routinely invoked in condensed matter physics. We have investigated the propagation of radiation through small numbers of meta-atoms or metamolecules, close to resonant frequencies, to determine how coupling and scattering affects their Q and bandwidth. From a scattering perspective, the coupling of local evanescent fields into propagating waves also contributes to these effective constitutive parameters in a subtle fashion determined by phase coherence. Depending on the materials employed from which the meta-atoms are fabricated, one can observe nonlinear responses. At microwave frequencies and using pulsed illumination, these structures show evidence of an energy exchange between neighboring (non-orthogonal) resonant modes, suggesting their use for tunable parametric applications as well. We discuss how these properties can be realized at optical frequencies.
University of Illinois, USA
Keynote: The transistor-injected quantum cascade laser: A novel three-terminal device for Mid-IR wavelengths through THz frequencies
Time : 10:15-10:40
Professor Dallesasse has over 20 years of experience in the Optoelectronics Industry, and has held a wide range of positions in technology development and management. Prior to joining the Department of Electrical and Computer Engineering at the University of Illinois in Urbana-Champaign, he was the Chief Technology Officer, Vice President, and co-founder of Skorpios Technologies, Inc., a company involved in the integration of compound semiconductor materials with silicon in a CMOS-compatible process. John’s research at the University is targeting photonic-electronic integration and novel coherent emitters for the mid-IR. His technical contributions include, with Nick Holonyak, Jr., the discovery of III V Oxidation, which has become an important process technology in the fabrication of high-speed VCSELs. John has over 60 publications and presentations, and 29 issued patents. He is a Fellow of the IEEE and OSA.
The quantum-cascade laser (QCL) has emerged as an important device for the generation of coherent light over operating bands from mid-IR wavelengths through THz frequencies. Wide-ranging applications in chemical detection and security have been enabled by the availability of these devices. At the same time, the device has certain limitations that are fundamental to its two-terminal nature and reliance on engineered quantum states that depend strongly on electric field, and as a consequence bias voltage. A promising enhancement to the QCL will be discussed that utilizes the transistor effect in a novel three-terminal n-p-n transistor structure to separate the field control from the current amplitude. This separation is achieved through placing the device cascade region in the reverse-biased base-collector junction of a heterojunction bipolar transistor (HBT), where the amplitude of the current flowing through the cascade region is controlled by the emitter-base bias. The ability to separately modulate the amplitude (emitter-base) and frequency (base-collector) creates unique opportunities for novel applications. The device design also allows a reduction of the doping level in and around the cascade region, which is ultimately expected to reduce free carrier absorption and improve wall-plug efficiency.