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

Photoluminescence characterization of GaxIn1−xAs (0 ≤ x ≤ 0.32) strained quantum wells grown on InP by chemical beam epitaxy

GaAlAs/GaAs surface emitting (SE) junction lasers have been fabricated by molecular beam epitaxy (MBE) It is easy for the MBE method to obtain a good flatness of grown surfaces to be utilized as reflective mirrors, and to control the thickness of the grown layer more precisely, compared with liquid phase epitaxy (LPE) We report on the room-temperature pulsed oscillation of a SE laser grown by MBE The threshold current was as low as 450 mA, and single-mode operation was achieved at λ = 8735 A

Room Temperature Pulsed Oscillation of GaAlAs/GaAs Surface Emitting Junction Laser Grown by MBE

We propose a novel parallel and bi-directional optical interconnect module using VCSELs and a 3-D stacked planar optical circuit. As an initial experiment of the optical circuit, we fabricate a stacked optical circuit chip and achieve an optical coupling loss of 2.4 dB.

Parallel and bi-directional optical interconnect module using vertical cavity surface emitting lasers (VCSELs) and 3-D micro optical bench (MOB)

An optical apparatus for controlling an angle of divergence of a ring beam which is capable of irradiating a ringed light beam having a uniform distribution of light intensity with an arbitrary angle of divergence with respect to the optical axis in the direction of 360° concurrently. The optical apparatus comprises parallel beam generating means (2) to which a light beam (L1) output from a light source (1) is input and which outputs the incident light (L2) by transforming into a parallel light beam (L3); ring beam generating means (3) to which the parallel beam (L3) output from the parallel beam generating means (2) is input and which outputs the input light (L4) by transforming into a ringed light beam (L5) whose shape is annular when irradiated to an imaginary plane vertical to an optical axis (A-A); and divergent angle changing means (4) for changing an angle of divergence (an angle formed between the optical axis (A-A) and the direction of propagation of the ring beam (L5)) (θ3) of the ring beam (L5) output from the ring beam generating means (3) on the way.

Optical apparatus for controlling divergence angle of ring-like ray

For the purpose of introducing a current-confining structure to a GaAlAs/GaAs surface emitting (SE) laser, a circular buried heterostructure (CBH) was proposed. A selective meltback method was employed in order to avoid the oxidization of GaAlAs. The threshold current of an SE laser was 300 mA under a pulsed condition at room temperature. The nominal threshold current density was 20 kA/cm2/µm.

Kenichi Iga

Papers

Photoluminescence characterization of GaxIn1−xAs (0 ≤ x ≤ 0.32) strained quantum wells grown on InP by chemical beam epitaxy

Room Temperature Pulsed Oscillation of GaAlAs/GaAs Surface Emitting Junction Laser Grown by MBE

Parallel and bi-directional optical interconnect module using vertical cavity surface emitting lasers (VCSELs) and 3-D micro optical bench (MOB)

Optical apparatus for controlling divergence angle of ring-like ray

A Trial Fabrication of Circular Buried Heterostructure (CBH) GaAlAs/GaAs Surface Emitting Laser by Using Selective Meltback Method