We will develop an on-demand and real-time reconfigurable broadcast technology for near-Earth space laser communication envisioned by NASA. By using a programmable phase-mirror, a communication laser beam from the master satellite can be dynamically diffracted into multiple narrow-width beams, and each narrow-width beam tracks a separate receiving satellite to deliver information. The advantages of this broadcast technology include highly efficient and secure (only targets illumination), more compact (by sharing one phase mirror aperture), and ease to modify the delivering approach of signals (programmable phase mirror).More »
Space mobile network desires to maximize coverage, availability, and link performance. By using a programmable phase-mirror, we propose to develop a real-time optical reconfigurable broadcast technology in order to improve existing on-demand forward link.
Optical space communication has many advantages compared to radio frequency (RF) one such as wide bandwidth (high data rate) and small size antenna. For on-demand forward link, optical broadcast technology is also in advanced of RF one. The RF signals usually corresponds to a wide divergence angle. The advantage is covering multiple slave satellites, the disadvantage is lack of efficiency and security. The laser transmitter of optical communication system usually launches a narrow-width (angular) beam. The scanning mirror can increase the coverage, but cannot simultaneously link to multiple satellites. Usage of multiple mirrors bulks and complicates the system and greatly increases technical difficulties. Thebroadcasting technology consisting of over a million tiny adjustable mirrors to diffract the single communication laser beam into multiple narrow beams as desired. The number of diffracted beams, their directions and angular beamwidths can be dynamically controlled by programming the phase delays of the tiny mirrors. This allows flexible, dynamic and on-demand broadcasting as desired for laser communication. The master laser can track dynamically track and communicate to multiple slave satellites. In this IRAD, we will experimentally demonstrate such lasercom broadcasting capability with a commercial off the shelf (COTS) phase mirror. To do this we will build experimental setup and develop control algorithm and software. We will also demonstrate the flexibility to widen the beamwidth of a beacon to allow a slave satellite to detect and acquire the beacon. We will design the optical system to allow the diffracted beams to be separated by large angles. This could allow a master GEO satellite to broadcast to other GEO satellites at large angular separations. We will also look into design options to incorporate such a phase mirror into the pointing, acquisition and tracking (PAT) subsystem of a lasercom system.More »
|Organizations Performing Work||Role||Type||Location|
|Goddard Space Flight Center (GSFC)||Lead Organization||NASA Center||Greenbelt, MD|