Mid-infrared free-space optical communication has a large potential for high speed communication due to its immunity to electromagnetic interference. However, data security against eavesdroppers is among the obstacles for private free-space communication. Here, we show that two uni-directionally coupled quantum cascade lasers operating in the chaotic regime and the synchronization between them allow for the extraction of the information that has been camouflaged in the chaotic emission. This building block represents a key tool to implement a high degree of privacy directly on the physical layer. We realize a proof-of-concept communication at a wavelength of 5.7 μm with a message encryption at a bit rate of 0.5 Mbit/s. Our demonstration of private free-space communication between a transmitter and receiver opens strategies for physical encryption and decryption of a digital message.
We proposed and experimentally demonstrated a free-space optical stealth communication system that hides the stealth signal in wide-band spontaneous emission noise. Spontaneous emission light sources have been widely used for illuminations and has been recently deployed for short distance and indoor free-space optical communications, such as LiFi. Since free-space optical communication is a broadcasting network, the users’ privacy is exposed to eavesdropping attacks. In this paper, stealth communication is achieved by taking advantage of the existing properties of spontaneous emission light sources, random phase fluctuations, and protects users’ privacy in free-space communication networks. The keys to hide and recover the stealth signal are the optical delays at the transmitter and receiver. Only by matching the delay length with the pre-shared keys can the authorized receiver recover the stealth signal. Without the right key, the eavesdropper receives a constant power that is the same as illumination light sources and cannot detect the existence of the stealth signal.
more » « less- NSF-PAR ID:
- 10378479
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Continuum
- Volume:
- 1
- Issue:
- 11
- ISSN:
- 2770-0208
- Page Range / eLocation ID:
- Article No. 2298
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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