30% external quantum efficiency from surface textured, thin-film light-emitting diodes

There is a significant gap between the internal efficiency of light-emitting diodes (LEDs) and their external efficiency. The reason for this shortfall is the narrow escape cone for light in high refractive index semiconductors. We have found that by separating thin-film LEDs from their substrates (by epitaxial lift-off, for example), it is much easier for light to escape from the LED structure and thereby avoid absorption. Moreover, by nanotexturing the thin-film surface using "natural lithography," the light ray dynamics becomes chaotic, and the optical phase-space distribution becomes "ergodic," allowing even more of the light to find the escape cone. We have demonstrated 30% external efficiency in GaAs LEDs employing these principles

Fast high-efficiency integrated waveguide photodetectors using novel hybrid vertical/butt coupling geometry

We report a novel coupling geometry for integrated waveguide photodetectors−a hybrid vertical coupling/butt coupling scheme that allows the integration of fast, efficient, photodetectors with conventional double heterostructure waveguides. It can be employed to yield a planar, or pseudo-planar, surface that supports further levels of integration. The approach is demonstrated with a 25-µm-long p-i-n detector integrated with an InP/InGaAsP/InP waveguide, which displays a high (~90%) efficiency and large (~15 GHz) bandwidth. This is the fastest high-efficiency integrated waveguide photodetector reported to date

Wavelength-selectable laser emission from a multistripe array grating integrated cavity laser

We report laser operation of a multistripe array grating integrated cavity (MAGIC) laser in which the wavelength of the emission from a single output stripe is chosen by selectively injection pumping a second stripe. We demonstrate a device that lases in the 1.5 µm fiber band at 15 wavelengths, evenly spaced by ~2 nm. The single-output/wavelength-selectable operation, together with the accurate predefinition of the lasing wavelengths, makes the MAGIC laser a very attractive candidate for use in multiwavelength networks

Ultracompact monolithic integration of balanced, polarization diversity photodetectors for coherent lightwave receivers

The authors have monolithically integrated an optical front-end on InP for balanced, polarization-diversity coherent lightwave reception which is only 1.3-mm long. Low on-chip insertion loss (<4.5 dB) and balanced photoresponse (1.05:1 or better) are achieved at 1.5-μm wavelength using straightforward, regrowth-free fabrication. Low-capacitance photodetectors (≤0.15 pF) are employed for high bandwidth operation

WDM Detection Using Integrated Grating Demultiplexer And High Density p-i-n Array

Multi-wavelength systems are being advocated for use in future telecommunication networks and for computer processor links. In research systems the multiplexing and demultiplexing of the different wavelength signals is currently achieved through the use of bulk optical components. When channel separation are on the order of a nm or so - which is typical of 'high density' direct detection systems - the MUX/DMUX function is generally done with a diffraction grating. WDM detection at the receiver end is then obtained by assembling a detector array, placed in the focal plane of the optical grating system

Lateral oxidation of InAlAs in InP-based heterostructures for long wavelength vertical cavity surface emitting laser applications

We have studied the wet thermal oxidation of In0.52Al0.48AsIn0.52Al0.48As and its potential application in current and optical confinement in vertical cavity surface emitting lasers (VCSELs). Two types of InP-based heterostructures were used to study the effect of adjacent layer compositions on the lateral oxidation behavior of the InAlAs. It was found that the oxidation of In0.52Al0.48AsIn0.52Al0.48As with InP adjacent layers, compared with In0.53Ga0.47AsIn0.53Ga0.47As adjacent layers, proceeded faster, more uniformly and with minimal degradation of the surrounding layers making it ideal for optoelectronic applications. © 1998 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70669/2/APPLAB-72-2-135-1.pd

Growth of high-quality GaAs/AlAs Bragg mirrors on patterned InP-based quantum well mesa structures

We have investigated the regrowth of GaAs/AlAs quarter-wave Bragg reflectors on patterned mesa InP-based quantum well heterostructures that can be fabricated into 1.55 μm vertical cavity surface emitting lasers. It is seen from transmission electron and scanning electron microscopy that the multiple layer GaAs-based mirrors can be grown on InP-based heterostructure mesas of diameters 10–40 μm without noticeable propagation of defects into the reflector layers or the quantum well region below. At the same time the photoluminescence from the quantum wells after regrowth indicates that lasers can be fabricated. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70502/2/APPLAB-71-5-581-1.pd