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Camouflage is a strategy that animals utilize for concealment in their habitat, making themselves invisible to their predators and preys. In RF systems, steganography or stealth transmission is the camouflage of information – a technology of hiding and transmitting secret messages in public media. Steganography conceals the secret message in publicly available media such that the eavesdropper or attacker will not be able to tell if there is a secret message to look for. Marine hatchetfish have two effective camouflage skills to help them hide from their predators – silvering and counterillumination. Silvering in marine hatchetfish uses its microstructured skin on its sides to achieve destructive interference at colors that could indicate the presence of the fish, while they also emit light at their bottom part to match its color and intensity to its surrounding, making it invisible from below, referred to as counterillumination. In this work, we borrow the two underwater camouflage strategies from marine hatchetfish, mimic them with photonic phenomena, and apply the camouflage strategies for physical stealth transmission of a 200 MBaud/s 16QAM OFDM secret signal at 5 GHz over a 25-km of optical fiber. The proposed bio-inspired steganography strategies successfully hid the secret signal in plain sight in temporal, RF spectral, and optical spectral domains, by blending in using counterillumination and turning invisible using silvering techniques. The stealth signal can only be retrieved with the precise and correct parameter for constructive interference at the secret signal frequency to unmask the silvering.
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Photonic tinkering in the open ocean
Billions of animals living in open water, or pelagic habitats, can disappear into their surroundings using a variety of light-manipulating camouflage solutions. These include transparent, antireflection, and glittery reflective structures. Although such photonic camouflage allows these animals to vanish into their surroundings, they still need to eat (and avoid being eaten), which requires the ability to detect their invisible neighbors. Thus, an arms race exists between predators and prey for the ability to see and yet not be seen ( 1 ). Evolutionary tinkering across the diversity of pelagic animals has produced multiple solutions for controlling the transmission, reflection, and detection of light. On page 695 of this issue, Shavit et al. ( 2 ) report the discovery of photonic glass materials that form the basis of sparkly “eyeglitter” in the larvae of pelagic crustaceans and allows for both reflective camouflage and vision. These findings present a mechanism for producing salient, tunable coloration and light manipulation in space-limited tissues.
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- Award ID(s):
- 1738567
- PAR ID:
- 10402486
- Date Published:
- Journal Name:
- Science
- Volume:
- 379
- Issue:
- 6633
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- 643 to 644
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1126/science.adf2062
