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

The vertical-cavity surface-emitting laser (VCSEL) is becoming a key device in high-speed optical local-area networks (LAN) and even wide-area networks (WAN) This device is also enabling ultra parallel data transfer in equipment and computer systems including storage area networks (SAN) and wide optoelectronics fields In this paper, we will review its conception, physics, and the progress of technology covering the spectral band from infrared to ultraviolet by featuring materials and fabrication technology Performances such as threshold, output power, polarization, modulation, and reliability are introduced Lastly, we will touch on its future prospects

https://ieeexplore.ieee.org/iel7/6708221/6715047/06715057.pdf

VCSEL — Its conception, development, and future

Diode characteristics of Li3N-diffused ZnSe grown by MOVPE

InGaAs/GaAs Strained Quantum Well Lasers with Etched Micro-Corner Reflectors

The dynamic wavelength shift or directly modulated vertical-cavity surface-emitting lasers (VCSELs) has been measured for the first time. The maximum wavelength shift at the resonance frequency of a 0.98 mu m InGaAs-GaAs VCSEL is approximately 0.7 AA. The authors calculated the wavelength shift by a large signal analysis using rate equations. The linewidth enhancement factor alpha is estimated to be 4 by fitting the measured data with the theory. >

Dynamic wavelength shift of vertical-cavity surface-emitting lasers

We have demonstrated the transmission of two-dimensional images by the use of a single piece of step-index multimode fiber We have used a pair of slits in front of and behind the fiber and those slits were rotated simultaneously to eliminate skew rays In each direction of the slits, light from the associated position of the point source was transmitted through the fiber and the image was reconstructed on film The result shows the applicability of this method of eliminating skew rays to transmit a two-dimensional image through a piece of step-index multimode fiber Some degradations on the image quality might be eliminated by improving the set up or using computer processing

Kenichi Iga

Papers

VCSEL — Its conception, development, and future

Diode characteristics of Li3N-diffused ZnSe grown by MOVPE

InGaAs/GaAs Strained Quantum Well Lasers with Etched Micro-Corner Reflectors

Dynamic wavelength shift of vertical-cavity surface-emitting lasers

Image Transmission by a Step-Index Multimode Fiber