Johns Hopkins University

Juan C Juarez

Joseph E Sluz

David W Young

Edward J Grave

Shwetha Ramkumar

Norman K Yeh

Radha A Venkat

Ryan P DiNello-Fass

James L Riggins, Ii

David A Kitchin

David M Brown

Hala J Tomey

David D Nicholes

Ricardo Luna

Melissa E Jansen

Katherine T Newell

Katherine T Souza

Michelle P O'Toole

Lauren S Weiss

A free-space optical (FSO) retransmission device includes a memory bank partitioned into at least a source buffer indexed by segment identifications (IDs), an interface in communication with an optical terminal and an Ethernet network, and a programmable circuit configured to execute data process operations. The data process operations include receiving data from the Ethernet network, generating an FSO segment including the data received from the Ethernet network and a segment ID, generating and transmitting an outgoing FSO frame to the optical terminal, the outgoing FSO frame including an outgoing FSO segment, and storing the outgoing FSO segment in the source buffer until a corresponding acknowledgement is received in an inbound FSO frame from the optical terminal.

Automatic repeat request network transport system for turbulent free-space optical communications links

A device includes an optical fiber bundle having at least one optical data fiber and at least three optical tracking fibers, a mirror package configured to direct an incoming optical beam to the optical fiber bundle, at least three detectors, each detector corresponding to one of the at least three optical tracking fibers, the at least three detectors configured to receive portions of the incoming optical beam from the corresponding optical tracking fibers and convert the portions of the incoming beam to electrical tracking signals, and a controller configured to receive the electrical tracking signals from the at least three detectors and generate a feedback control based on the electrical tracking signals to control a position of the mirror package.

Free-space optical terminal

An optical communications beacon receiver including a camera for capturing a plurality of beacon images. The plurality of beacon images includes a beacon signal transmitted from a beacon transmitter. The beacon receiver also including processing circuitry configured for determining the state of the beacon signal for each of the plurality of beacon images based on the known pattern, at least one beacon image of the plurality of beacon images includes a beacon on state and at least one beacon image of the plurality of beacon images includes a beacon off state, comparing the at least one beacon image including the beacon on state to the at least one beacon image including the beacon off state, and determining a beacon location based on the comparison of the at least one beacon image including the beacon on state to the at least one beacon image including the beacon off state.

Free space optical communication

To stabilize power to an optical multimode receiver a multimode variable optical attenuator is connected to the receiver with the attenuator's voltage being controlled using a feedback signal provided by an output detector, the signal being processed using a control algorithm based on proportional-integrate-differential theory.

Apparatus and method for stabilizing power to an optical multimode receiver

At least two single-mode optical fibers are fused together such that their cores are separated by only a few microns to serve as a capture element of an incoming beam of light in an optical terminal.

Apparatus and method for increasing the effective capture area in optical terminals

Methods and systems to control a gain applied to a free-space optical (FSO) signal to reduce time-varying intensity fluctuations. An optical pre-amplifier may provide a first, relatively moderate gain with low noise factor (NF). A second optical amplifier may provide a second gain. Amplification may include doped fiber amplification (DFA), such as erbium-doped fiber amplification (EDFA) and/or Raman amplification. A variable optical attenuator (VOA) may be controllable with a relatively fast response time to reduce the time-varying intensity fluctuations. The VOA may effectively control an overall system gain. The gain of the first and/or second optical amplifier may also be controllable to reduce the time-varying intensity fluctuations. Optical intensities may be detected at one or more locations to support one or more feed-forward and/or feedback control loops. A clamp may be applied when an optical power reaches a threshold.

Fiber-optic automatic gain control systems and methods

A customized bit error rate tester that characterizes data transmission through a free space optical channel that overcomes the limitations of commercial based bit error rate testers by providing visibility into packet based channel capacity by measuring bit-level statistics not dominated by fades. In this manner, fade characteristics can be measured and a relationship between fade time and data packet lengths can be developed. Further, analog outputs provide visual real-time data link statistics.

Growing community of inventors

Windsor Mill, MD, United States of America

Juan C Juarez