We present models for the optical functions of 11 metals used as mirrors and contacts in optoelectronic and optical devices: noble metals (Ag, Au, Cu), aluminum, beryllium, and transition metals (Cr, Ni, Pd, Pt, Ti, W). We used two simple phenomenological models, the Lorentz-Drude (LD) and the Brendel-Bormann (BB), to interpret both the free-electron and the interband parts of the dielectric response of metals in a wide spectral range from 0.1 to 6 eV. Our results show that the BB model was needed to describe appropriately the interband absorption in noble metals, while for Al, Be, and the transition metals both models exhibit good agreement with the experimental data. A comparison with measurements on surface normal structures confirmed that the reflectance and the phase change on reflection from semiconductor-metal interfaces (including the case of metallic multilayers) can be accurately described by use of the proposed models for the optical functions of metallic films and the matrix method for multilayer calculations.

Optical properties of metallic films for vertical-cavity optoelectronic devices.

The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation, and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes, and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

Gan : processing, defects, and devices

1. Introduction and overview 2. Film stress and substrate curvature 3. Stress in anisotropic and patterned films 4. Delamination and fracture 5. Film buckling, bulging and peeling 6. Dislocation formation in epitaxial systems 7. Dislocation interactions and strain relaxation 8. Equilibrium and stability of surfaces 9. The role of stress in mass transport.

Thin Film Materials: Stress, Defect Formation and Surface Evolution

The ability to control the modes oscillating within a laser resonator is of fundamental importance. In general, the presence of competing modes can be detrimental to beam quality and spectral purity, thus leading to spatial as well as temporal fluctuations in the emitted radiation. We show that by harnessing notions from parity-time (PT) symmetry, stable single–longitudinal mode operation can be readily achieved in a system of coupled microring lasers. The selective breaking of PT symmetry can be used to systematically enhance the maximum attainable output power in the desired mode. This versatile concept is inherently self-adapting and facilitates mode selectivity over a broad bandwidth without the need for other additional intricate components. Our experimental findings provide the possibility to develop synthetic optical devices and structures with enhanced functionality.

http://science.sciencemag.org/content/sci/346/6212/975.full.pdf

Parity-time–symmetric microring lasers

In this review article a comprehensive analysis of the developments in ultraviolet (UV) detector technology is described. At the beginning, the classification of UV detectors and general requirements imposed on these detectors are presented. Further considerations are restricted to modern semiconductor UV detectors, so the basic theory of photoconductive and photovoltaic detectors is presented in a uniform way convenient for various detector materials. Next, the current state of the art of different types of semiconductor UV detectors is presented. Hitherto, the semiconductor UV detectors have been mainly fabricated using Si. Industries such as the aerospace, automotive, petroleum, and others have continuously provided the impetus pushing the development of fringe technologies which are tolerant of increasingly high temperatures and hostile environments. As a result, the main efforts are currently directed to a new generation of UV detectors fabricated from wide band‐gap semiconductors the most promising ...

Semiconductor ultraviolet detectors

This paper proposes a surface-emitting-type optical threshold device and analyzes its characteristics. For a surface-emitting laser resonator with a saturable absorber, its static characteristics and small signal analysis with a current or light injection are obtained from rate equations. As a result, the possibility of an optical threshold device which operates with a practical optical energy of approximately 30 kW/cm2 has been shown. Furthermore, it has been shown that the optical threshold varies by controlling an injection current, and that AND and OR logics are possible with one device. As a result of small signal analysis, the device is shown to have a bandwidth of approximately 1 GHz.

Analysis of the operation of surface‐emitting‐type optical threshold device

We have fabricated a 20 pair MgO-SiO/sub 2/ dielectric multilayer reflector by an electron-beam evaporation system on Si substrates This system can introduce the oxygen gas during the deposition to avoid the lack of oxygen, and each layer can be alternatively evaporated while monitoring the thickness with a crystal sensor

MgO/SiO/sub 2/ dielectric multilayer reflectors for GaN-based ultra-violet surface emitting lasers

The diffraction losses of transverse modes of a surface emitting laser are studied by beam propagation method and the condition of single mode operation that when the diameter of one side mirror is about 5 μm, fundamental transverse mode operation can be achieved, is given

Estimation of Diffraction Loss in Surface Emitting Laser Cavity by Beam Propagation Method

0.33-mA-threshold InGaAs/GaAs vertical-cavity surface-emitting lasers grown by MOCVD

The authors propose a miniature semiconductor optical power splitter with a submicrometre wide input aperture enhancing lightwave diffraction in a planar free-space region. They present its design and have demonstrated a GaInAs-GaAs quantum well laser with a miniature 1/spl times/20 power splitter inside the laser cavity.

Kenichi Iga

Papers

Analysis of the operation of surface‐emitting‐type optical threshold device

MgO/SiO/sub 2/ dielectric multilayer reflectors for GaN-based ultra-violet surface emitting lasers

Estimation of Diffraction Loss in Surface Emitting Laser Cavity by Beam Propagation Method

0.33-mA-threshold InGaAs/GaAs vertical-cavity surface-emitting lasers grown by MOCVD

Miniature semiconductor optical power splitters with submicrometre wide aperture