The technology advances made in the development of an engineering feasibility model of a Nd:YAG laser communication system for space test are discussed and details of evaulations presented. The model includes the baseplate, optomechanical structure, 19-cm (7.5-in) diameter telescope and prototype space qualifiable components. The main technological achievements are in the areas of laser and its operation, the modulator and the digital format, and the integration of the various optical components into one optomechanical structure. These as well as other technology advances will be discussed and the system performance capabilities indicated.

1000-Mbits/s intersatellite laser communication system technology

A major field of research at the current time is that of implementing Quantum Key Distribution over large distances using satellites. If this protocol works with this technology, it will have huge implications on future information security. In order for a satellite to implement this idea, there are many aspects that must be taken into account. One of the big issues that comes up for this type of system is that of propagating light through the turbulent atmosphere and its effects on the acquisition, pointing and tracking system. The projects studied in this thesis study some of the effects of the atmosphere on certain detectors, try to develop pointing schemes for better accuracy as well as develop knowledge in free space propagation of other single photon experiments. In the first experiment, I study the spatial correlations of the daughter photons created in spontaneous parametric down conversion. I look at the effect of altering the pump beam on the positions of the down converted photons and see if the pump can be manipulated in a way to control the directions of the daughter photons. I begin to utilize a deformable mirror and Shack-Hartmann wavefront sensor which are generally used in adaptive optics, but we plan to use them to alter the pump beam in the spontaneous parametric down conversion process to analyze the correlations between the pump and down converted photons. The second experiment investigates the effects of laser scintillation on the performance of a possible tracking device that could be implemented on a satellite. This quad sensor tracks the position of a beam and a system will be developed to move the sensor to keep the beam in the center where there is a hole for the quantum single photons to stream through. In order to create the effects of scintillation, a turbulence simulator box was built and characterized. This box combines wind turbulence with a heat gradient to mimic atmospheric turbulence on a small scale. Finally, my contributions to a large scale, long distance free space quantum optics experiment are explained and the overall goal of the experiment is discussed. This experiment exposed me to actual free space transmission issues as well as many fundamental techniques for performing long distance optics experiments. In this experiment there was no correction for atmospheric turbulence, but in the future, techniques could be implemented which might increase the efficiencies of the free space links.

Experimental Investigation into Spatial Quantum Optical Properties for Satellite Targeting through the Turbulent Atmosphere

Since it was first proposed, the space solar power station (SSPS) has attracted great attention all over the world; it is a huge space system and provides energy for Earth. Although several schemes and abundant studies on the SSPS have been proposed and conducted, it is still not realized. The reason why SSPS is still an idea is not only because it is a giant and complex project, but also due to the requirement for various excellent space materials. Among the diverse required materials, we believe energy materials are the most important. Herein, we review the space energy conversion materials for the SSPS.

Energy conversion materials for the space solar power station

Two different kinds of dynamic stable resonator—the resonator insensitive to axial shift of the mirrors of the resonator, and the resonator insensitive to thermo-perturbation of the thermo-lens in the resonator—and their general criteria are distinguished in detail. At the same time both coincident conditions are also discussed.

Two Different Kinds of Dynamic Stable Resonator and Their General Criteria


 Since it was first time proposed, the Space Solar Power Station (SSPS) has attracted great attention all over the world, which is a huge space system and provide energy for Earth. Although several schemes and abundant studies on SSPS have been proposed and conducted, it is still unrealized. The reason why SSPS is still an idea, not only because it is a giant and complex project, but also due to the requirement of various excellent space materials. Among the diverse required materials, we believe energy materials are the most important. Herein, we reviewed the space energy conversion materials for SSPS.

Energy Conversion Materials for Space Solar Power Station

Space laser communications with the frequency doubled Nd-YAG laser offers the most efficient means for transferring wideband data from one satellite to another. A space test in 1981 of the Nd-YAG laser system operating at a rate of 1 000 Mbit s-1 will establish the basis for future systems. The system offers growth capability beyond conventional systems and is a major step forward in the application of a low power laser. The Nd-YAG laser design as well as its principles of operation are constrained by the space application. The laser is now conductively cooled, mode-locked, and frequency-doubled, and will be so operated in space. The space system will use both solar and lamp pumped lasers to allow alternate modes of operation.

J.D. Barry

Papers

Space communications: Practical application of a visible Nd: YAG laser