Implementing new solar panel technology is often hampered by the difficulty in obtaining flight heritage and integrating experimental technology into conventional panels. Modular solar panel technology overcomes this limitations by allowing substitution of an experimental module into a modular flight arrays using mostly conventional modules. The approach also allows the benefits of full-scale testing when test article sizes are limited, and easier repairability by allowing damaged modules to be unplugged and repaired off-line. The Modular Solar Array with Integrated Construction (MOSAIC) technology described in this paper is being flight tested on an experiment called MATRS (Modular Array Technology for Reconfigurable Spacecraft). The flight test unit includes modules with conventional space cells, as well as advanced modules incorporating 4-junction IMM cells to demonstrate the ease of ground integration and replacement of the modular approach, incorporation of experimental modules in flight, and life cycle performance.

Monolithic interconnected modules (MIMs) are under development for thermophotovoltaic (TPV) energy conversion applications. MIM devices are typified by series-interconnected photovoltaic cells on a common, semi-insulating substrate and generally include rear-surface infrared (IR) reflectors. The MIM architecture is being implemented in InGaAsSb materials without semi-insulating substrates through the development of alternative isolation methodologies. Motivations for developing the MIM structure include: reduced resistive losses, higher output power density than for systems utilizing front surface spectral control, improved thermal coupling and ultimately higher system efficiency. Numerous design and material changes have been investigated since the introduction of the MIM concept in 1994. These developments as well as the current design strategies are addressed.

Thermophotovoltaic (TPV) tandem converter technology is being explored in an effort to improve the efficiency of TPV systems while maintaining high power densities. Series-connected (SC) tandem structures incorporate epitaxially grown 0.74 eV lattice-matched Ga/sub 0.47/In/sub 0.53/As and 0.63 eV lattice-mismatched Ga/sub 0.36/In/sub 0.64/As diodes. Structures have been grown using OMVPE and devices have been fabricated via wet-chemical processing. The 10-cell SC tandem MIM reported here produced 6.14 V in the open-circuit condition, 0.292 A/cm/sup 2/ in the short-circuit condition, and exhibited a fill factor of 67.6%. These values were measured at a cell temperature of 52/spl deg/C using a low emissivity /spl sim/1000/spl deg/C graybody illumination source. To our knowledge, these results are the first-of-a-kind for SC tandem MlMs.

Starshine 3 is principally a passive experiment measuring atmospheric density and does not need electrical power to complete its mission. The requirement for a highly reliable power system is therefore greatly reduced. This creates an excellent opportunity to test new power technologies. The Starshine 3 satellite has a power supply that uses triple-junction, GaInP/GaAs/Ge solar cells and rechargeable lithium-ion batteries. This satellite is the first to use both of these advanced technologies for a primary power system. In addition to the power system, several other PV related experiments are on board Starshine 3. The results from the first 3 months of operation are presented.

We have observed In out diffusion from strained InxGa1−xAs quantum wells into the adjacent GaAs barriers in degraded 980-nm-wavelength strained quantum-well lasers. A previous calculation on misfit stress-induced compositional instability indicates that this material system is stable with respect to misfit strain. Therefore, the out diffusion of In from an InxGa1−xAs quantum well is mainly driven by the compositional discontinuity across the well/barrier heterointerfaces, and is believed to be activated by the nonradiative recombination of injected carriers.

Low pressure metal-organic vapor phase epitaxy (MOVPE) is the dominant technology for the fabrication of transmitters and detectors for the fiber optic communication industry. These high bandwidth devices typically utilize heterostructure designs incorporating strained multiple quantum well active regions. The epitaxial growth of such structures incorporates a complicated sequence of growth and regrowth steps over planar and non-planar surfaces. Abrupt interfaces, precise thickness and composition control, and uniformity are essential for high yield, high throughput manufacturing. More advanced devices integrate modulator or waveguide structures monolithically on the transmitter chip through extensive bandgap engineering. This can be accomplished by taking advantage of localized growth modifications occurring during selective area growth (SAG). Furthermore, advances in the purity levels of both the metal-organic and gas sources have enabled MOVPE grown materials to meet the low doping and high mobility levels required for detector structures. MOVPE offers a robust, high throughput, and flexible platform to meet the ever increasing demands for optoelectronic component manufacturing.

We report measurements of excess wavelength chirp caused by high frequency electrical crosstalk between an electroabsorption modulator and the tuning section of a monolithically integrated DBR laser. The high tuning efficiency of the laser leads to stringent electrical isolation requirements. (C) 2000 Optical Society of America.

This paper reviews the development of the semiconductor laser — a key component of optical communications. It discusses the tremendous advances in materials and reliability, describes the progress in laser structures, performance, and applications, and looks forward to the role of the laser in the next phase of the telecommunications revolution.

The invention of the Er-doped optical amplifier has revolutionized the world of long-wavelength transmission systems. With the use of 1.55 μm optical line amplifiers, transmission systems utilizing 1.55 μm DFB lasers can reach span distances of 200 km (direct modulation) to 1000 km (external modulation) before the need for electrical regeneration of the transmitted signal. Further, the extreme bandwidth (>30 nm) of these Er-doped line amplifiers has enabled the use of several densely populated WDM carriers on the same optical line, sharing the same amplifier chain. Current systems employ carrier wavelength spacings on the order of 0.8 nm (100 GHz), while proposed systems may employ spacings as small as 0.2 nm (25 GHz). In order for these systems to operate with minimal impairment, the transmission sources employed (cooled DFB lasers) must be stable enough to prevent excessive loss in multiplexers/demultiplexers or cross-channel interference. For a typical 100 GHz system, this implies a required wavelength stability of 0.2 nm (25 GHz)

In this paper, a review of the state-of-the-art in semiconductor laser diode reliability is presented, with a particular regard to the reliability of laser diodes used in long-distance telecommunication system. Remarkable advances in semiconductor laser reliability have been demonstrated over their thirty year history, leading to estimated median device lifetimes in excess of 100 years for most applications.