&lt;title&gt;Low-power FLC-based retromodulator communications system&lt;/title&gt;

Swenson, C.; Steed, Clark A.; Rue, Imelda A. De La; Fugate, Robert Q.

doi:10.1117/12.273706

Cited by 55 publications

(29 citation statements)

References 5 publications

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“…The concept was successfully demonstrated by the Air Force in 1997 using Ferro Liquid Crystal devices. [4] The concept has also been explored using the Stark effect at 10.6 microns [5] and in the microwave regime [6]. However, these device technologies are inherently slow, can be fragile, and can require high power draws.…”

Section: The Conceptmentioning

confidence: 99%

Retromodulator for Optical Tagging for LEO Consumables

Gilbreath¹,

Meehan²,

Rabinovich³

et al. 2007

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Abstract-In this paper, we report the results of a recent demonstration in which a Multiple Quantum Well retromodulator array was used as a low power, lightweight means to provide optical tagging of a remotely located object. A laser diode integrated on a tracker/pointing system scanned without cueing for a modulated retroreflected beam. The retroreflected energy was received and the embedded code demodulated for tagging identification. Ranges were on the order of 40 meters using an array of 1/2 cm MQW devices. Data were transferred at a rate of one mega chip per second over the link. Device power requirements were on the order of several milliwatts.

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Section: The Conceptmentioning

confidence: 99%

Retromodulator for Optical Tagging for LEO Consumables

Gilbreath¹,

Meehan²,

Rabinovich³

et al. 2007

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“…Unlike quantum limited systems in which the noise level increases as the optical contrast ratio decreases the noise level in this case is independent of the optical contrast ratio. (2) where P On is the optical power returned by the MQW MRR when it is in its on-state, P Off is the power returned in the offstate, P noise is the noise equivalent power of the detector, P Ret is the optical power returned by the MRR excluding losses in the MQW modulator, On is the double-pass absorption-length product of the MQW in it's on-state and Off in its offstate. From equation 2 it can be seen that maximizing the OSNR depends on both the optical contrast ratio and the optical transmission of the MQW.…”

Section: Modulating Retro-reflector Linksmentioning

confidence: 99%

“…The MRR demonstrated to date have used a large area modulator placed in front of the aperture, or as one of the faces, of a corner-cube retro-reflector. MRR based on ferroelectric liquid crystals [2], MEMS devices [3] and multiple quantum well (MQW) electro-absorption modulators [4], [5] have been demonstrated recently For both the liquid crystal and MEMS devices the maximum modulation rate is set by the intrinsic switching speed of the material, which are tens of KHz and hundreds of KHz respectively. For the MQW MRR however, the maximum telescope modulation can range into the gigahertz, limited only by the RC time constant of the device.…”

Section: 1mentioning

confidence: 99%

Performance of cat's eye modulating retro-reflectors for free-space optical communications

et al. 2004

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Modulating retro-reflectors (MRR) couple passive optical retro-reflectors with electro-optic modulators to allow free-space optical communication with a laser and pointing/acquisition/tracking system required on only one end of the link. In operation a conventional free space optical communications terminal, the interrogator, is used on one end of the link to illuminate the MRR on the other end of the link with a cw beam. The MRR imposes a modulation on the interrogating beam and passively retro-reflects it back to the interrogator. These types of systems are attractive for asymmetric communication links for which one end of the link cannot afford the weight, power or expense of a conventional free-space optical communication terminal. Recently, MRR using multiple quantum well (MQW) modulators have been demonstrated using a large area MQW placed in front of the aperture of a corner-cube.For the MQW MRR, the maximum modulation can range into the gigahertz, limited only by the RC time constant of the device. This limitation, however, is a serious one. The optical aperture of an MRR cannot be too small or the amount of light retro-reflected will be insufficient to close the link. For typical corner-cube MQW MRR devices the modulator has a diameter between 0.5-1 cm and maximum modulation rates less than 10 Mbps. In this paper we describe a new kind of MQW MRR that uses a cat's eye retro-reflector with the MQW in the focal plane of the cat's eye. This system decouples the size of the modulator from the size of the optical aperture and allows much higher data rates. A 10 Mbps free space link over a range of 1 km is demonstrated. In addition a laboratory demonstration of a 70 Mbps MQW focal plane is described.

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“…The idea was successfully demonstrated by Swenson, et. al., using a balloon in flight with a Ferro Liquid Crystal (FLC) shutter in 1996 [1].…”

Section: Supplementary Notesmentioning

confidence: 99%

<title>Compact lightweight payload for covert datalink using a multiple quantum well modulating retroreflector on a small rotary-wing unmanned airborne vehicle</title>

Gilbreath

Rabinovich

Meehan

et al. 2000

Airborne Reconnaissance XXIV

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In this paper, we describe progress in the development of the NRL Multiple Quantum Well modulating retroreflector including a description of recent demonstrations of an infrared data link between a small rotary-wing unmanned airborne vehicle and a ground based laser interrogator using the NRL multiple quantum well modulating retro-reflector. Modulating retro-reflector systems couple an optical retro-reflector, such as a corner-cube, and an electro-optic shutter to allow two-way optical communications using a laser, telescope and pointer-tracker on only one platform. The NRL modulating retroreflector uses a semiconductor based multiple quantum well shutter capable of modulation rates up to 10 Mbps, depending on link characteristics. The technology enables the use of near-infrared frequencies, which is well known to provide covert communications immune to frequency allocation problems. The multiple quantum well modulating retro-reflector has the added advantage of being compact, lightweight, covert, and requires very low power. Up to an order of magnitude in onboard power can be saved using a small array of these devices instead of the Radio Frequency equivalent. In the described demonstration, a Mbps optical link to a unmanned aerial vehicle in flight at a range of 100-200 feet is shown. Near real-time compressed video is also demonstrated at the Mbps level.

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<title>Low-power FLC-based retromodulator communications system</title>

Cited by 55 publications

References 5 publications

Retromodulator for Optical Tagging for LEO Consumables

Retromodulator for Optical Tagging for LEO Consumables

Performance of cat's eye modulating retro-reflectors for free-space optical communications

<title>Compact lightweight payload for covert datalink using a multiple quantum well modulating retroreflector on a small rotary-wing unmanned airborne vehicle</title>

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