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

Laser Gain and Saturation

A dynamic-single-mode laser has become important as a light source for optical fiber communications using a 1.5 μm wavelength band, and a surface emitting laser is promising as one of them. However, a good ohmic contact must serve simultaneously as a mirror and it was difficult by a present technique to obtain a reflective mirror with high reflectivity. In this paper, we apply the multilayer heterostructure with the thick ness of quarter wavelength to the surface emitting laser reflector to solve the difficulty. First: (1) we analyzed the semiconductor multilayer DBR by expanding the multilayer film theory to calculate the complex field reflectivity r and obtained the power reflectivity R and the effective optical path length which is practically effective to the DBR laser. Then we clarify the lasing condition of the surface emitting laser using the semiconductor multilayer DBR.

Analysis of semiconductor multilayer and its application to surface emitting lasers

Polarization Characteristics Of Oxide Confinement Vertical-cavity Surface-emitting Lasers Grown On GaAs(311 ) A Substrates

A dry etching technique is important for microfabrication of photonic devices, including semiconductor microcavities. Smooth etched sidewalls are needed to form low loss semiconductor microcavities and optical waveguides, because rough surfaces cause noticeable scattering losses. So far, scattering losses in etched reflectors or waveguides caused by interface roughness have been theoretically studied. Scattering losses should be dependent on not only the amplitude of roughness but also its correlation length; however the spatial frequency of the roughness of etched surfaces has not been discussed yet. In this paper, we present a spatial frequency analysis of the measured sidewall roughness of dry etched InP facets, and the correlation length of the sidewall roughness is estimated from the power spectrum to discuss its effect on reflectivities of the etched facet.

Fabrication of InP vertical facets by reactive ion etching and sidewall roughness evaluation for semiconductor microcavities

This paper describes the fabrication and basic properties and optical property of a GaAs/AlGaAs surface-emitting laser-type optical threshold device. Initially, a GaAs/AlGa-As surface-emitting optical threshold device with a mesa cap ring electrode structure (active layer of 3 μm and absorption layer of 0.5 μm) was fabricated and it was found that the device had a threshold current of 430 mA under room temperature pulse operation. To confirm whether the absorption layer was effective, the slow pulse response was calculated theoretically. Then, it was confirmed that an asymmetrical optical pulse can be obtained experimentally. Then a nonlinear optical input-output was obtained at the input optical density of about 100 W/cm2.

Kenichi Iga

Papers

Laser Gain and Saturation

Analysis of semiconductor multilayer and its application to surface emitting lasers

Polarization Characteristics Of Oxide Confinement Vertical-cavity Surface-emitting Lasers Grown On GaAs(311 ) A Substrates

Fabrication of InP vertical facets by reactive ion etching and sidewall roughness evaluation for semiconductor microcavities

Pulse operation of GaAs/ALGaAs surface‐emitting laser‐type optical threshold device