Research in free-space optical data transfer at the U.S. Naval Research Laboratory

Abstract

In this paper, a review of the progress and initiatives in free space optical data transfer and communications at the Naval Research Laboratory is presented. NRL has been investing in research and development in optical communications and laser ranging, both conventional, and advanced. Efforts include developing amplifiers and components for lasers to be used in long range, one-way and retro-reflected links. NRL has been developing Multiple Quantum Well retromodulators for space-based and terrestrial-based applications as well. These include spacecraft-to-spacecraft data links for navigation and communications, intra-bus networks on spacecraft, and optical tagging. Terrestrial applications in the eyesafe regime have led to additional studies in how the atmosphere affects one-way and modulated retroreflected signals in the maritime environment, in particular. New results from retrodiversity experiments, over-the-water propagation studies, and field tests are discussed. INTRODUCTIONThe Naval Research Laboratory (NRL) has been investing in advanced optical data transfer techniques since the 1970's. Recent studies include efforts in optical communications and satellite laser ranging, both conventional and advanced. At this time, NRL has two ongoing 6.2 programs in optical communications and tagging. These programs address high data rate links -tens of gigabits per second (Gbps) -and passive optical terminals based on Multiple Quantum Well (MQW) retromodulators which operate at megabits per second (Mbps) [1][2][3]. NRL also supports a dual interrogator program for retromodulator data links administered through the Office of Naval Research (ONR), as well as perform as SBIR advisors for advanced optical communications applications serving Navy needs. NRL's goals for these programs are to demonstrate feasibility and conduct engineering science in device development and atmospheric effects as they pertain to data links in the near infrared. To achieve these goals, investigations are ongoing in device and technology development, in techniques, such as forward adaptive error correction, and in atmospheric propagation. Figure 1 shows a break out of technologies and techniques explored as a function of data rate. This paper summarizes progress in these areas at NRL.It should be noted that the NRL has a satellite laser ranging site located on the east coast which offers a 1 meter telescope, 3 Watt 1.06 micron laser which has a pulse repetition frequency of 10 Hz. This paper will not address progress at the facility but details are available in the references [4,5]. Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters ...

Performance Analysis in Free Space Optical Communication System Using Aperture Averaging

“…This will reduce the loss of radiations due to increased beam divergence. The aperture size of the receiver is increased so that most the radiance is collected by the lens [6,1].…”

Performance analysis of free space optical–based wireless sensor networks using corner cube retroreflectors

“…This clause proposes novel performance analysis for CCR‐based FSO‐WSN system employing intensity modulation/direct detection (IM/DD) with on‐off keying modulation (OOK) over variant atmospheric turbulent channel conditions. It is considered that the transmitter and the receiver are located at different locations . As such, the double pass channel (ie, forward and backward paths of the communication link) is modeled as a product of two independent turbulence channels, which is usually called a bistatic channel, and different turbulence‐induced fading models are considered.…”

Study on the heterodyning scattering of retroreflective free-space optical communication with optical heterodyning

“…Several experiments of retroreflective free-space optical communication have been done, and the communication ranges are usually several kilometers [6][7][8][9][10][11]. It should be noted that the long-range experiments in [6][7][8][9][10] were done under good weather conditions.…”

“…It should be noted that the long-range experiments in [6][7][8][9][10] were done under good weather conditions. However, link failure caused by bad weather conditions will occur not only when the desired retroreflective signal is attenuated, but when scattering of the transmitted light is increased.…”