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 authors investigated some fundamental characteristics of chemical beam epitaxy (CBE) grown GaInAsP/InP multiple quantum wells (MQWs) for a wavelength tuner and estimated the wavelength shift for realizing wavelength tunable surface emitting (SE) lasers. They observed the quantum confined Stark effect in a GaInAsP/InP MQW structure grown by CBE and estimated the refractive index change, which was as large as 1%. By using these results, the possibility realizing a wavelength tunable SE laser with a MQW tuner is exhibited and the maximum wavelength change is expected to be as large as 7/spl Aring/. >

Loss and index change in GaInAsP/InP multiple quantum well QCSE tuning element for surface emitting lasers

GaN growth on ozonized sapphire(0 0 0 1) substrates by MOVPE

PROBLEM TO BE SOLVED: To provide an optical fiber connecting unit, a method and structure that can directly join not only single but also multiple optical fibers without using a connector and that can easily join optical fibers without using a matching oil. SOLUTION: In the connecting unit 1, on the upper face 20 side of the unit body 2, there are arranged a pair of fiber holders 3, 3 constituting a holding means, a block 5 formed with a cross-sectionally nearly V-shaped V-groove 4, and a dial 6 which is operated when the block 5 is moved vertically in Fig. 1 along the hole 21 provided on the unit body 2. The unit body 2 consists of a storage part 22 and a cover 23, and contains in its inside a slide member 7 which fixes on its one end the bottom 50 of the block 5, which is placed so as to be freely slidable, and which is provided with a vertically elongated arm 70 on the other end, an eccentric cam 8 which is fixed coaxially with the dial 6 through a shaft 80, an axial support base 9 for axially supporting the eccentric cam 8, and tension springs 10, 10 which energize the eccentric cam 8 against the arm 70 of the slide member 7.

Optical fiber connecting unit, method and structure

The effect of inelastic scattering on electron reflection in multiquantum barriers has been examined for the first time by using the damped resonant tunneling model. The electron reflectivity exhibits marked deterioration to values below unity at discrete energies in the virtual barrier. The largest dip in reflectivity is about 15% for an intraband relaxation time of 0.16 ps. It is also shown that this deterioration can be reduced by utilizing a strain-compensated superlattice in the multiquantum barriers.

Study of Inelastic Scattering Effect in Unstrained and Strain-Compensated GaInAs/GaInP Multiquantum Barriers

Summary form only given. It is expected that an n-type modulation-doped quantum well (QW) lasers can achieve a reduction in threshold current. In this report, we have demonstrated strained InGaAs-AlGaAs QW lasers employing the n-type modulation doping for reducing threshold current for the first time. The active region of QW lasers was grown by a low pressure metal organic chemical vapor deposition.

Kenichi Iga

Papers

Loss and index change in GaInAsP/InP multiple quantum well QCSE tuning element for surface emitting lasers

GaN growth on ozonized sapphire(0 0 0 1) substrates by MOVPE

Optical fiber connecting unit, method and structure

Study of Inelastic Scattering Effect in Unstrained and Strain-Compensated GaInAs/GaInP Multiquantum Barriers

N-type modulation-doped strained InGaAs/AlGaAs quantum well lasers grown by metal organic chemical vapor deposition