Optical wireless systems operate in the near infrared wavelength range slightly

With its cost-effective and high-bandwidth qualities, optical wireless products operating in the near infrared wavelength range are an alternative transport technology to interconnect highcapacity networking segments. Therefore,it is understandable why the study of FSO technology in military labs and security agencies dates back several decades. In the majority of cases, the installation location does not allow free access to a potential intruder because the installation location is part of the customerpremise such as the roof or an office (when optical wireless equipment is installed behindwindows). Due to the fact that the transmission beam is invisible and that any attempts to block the beam would occur near the optical wireless equipment terminus points, the transmission process imposes another obstacle. In the early days of FSO development, the ability to transmit information at high data rates was actually a less important factor than the fact that FSO technologiesoffered one of the easiest and most secure ways to exchange information between remote locations. Picking up the signal from a location thatis not directly located within the light path by using light photons scattered from aerosol, fog, or rain particles that might be present in the atmosphere is virtually impossible because of the polyester air layer fabric extremely low infrared power levels used during the optical wireless transmission process. Even more difficult, the intruder must have free and undisturbed access to the installation location of the optical wireless transceiver and be able to install electronic equipment without being observed. Due to the very narrow beam diameter, interception of the beam can virtually only be accomplished at the customer premise where the system is installed. One of the main reasons for this concern is based on the fact that wireless networking solutions is a category in which security and interference problems are very common in radio frequency (RF) or microwave-based communication systems.

Because optical wireless systems send and receive data through the air between remote networking locations, network operators and administrators are naturally concerned about thesecurity aspects. Although it is extremely unlikely that it is possible to break into a sophisticated encryption code, there is always the concern that it can be done. To overcome these security concerns, the microwave industry uses wireless encryption protocols (WEP) to protect the transmission path from being intercepted. At that point, it would be certainly easier for an intruder to plug directly into the network by using the existing copper-based infrastructure (e. Therefore, the human eye cannot visibly see the transmission beam.

Optical wireless systems operate in the near infrared wavelength range slightly above the visible spectrum.Moreover, higher protocol layers can be used in conjunction with layer one optical wireless physical transport technology to encrypt sensitive network information and provide additional. This specific scattering mechanism keeps the total number of photons or the amount of radiation that can potentiallybe collected onto a detector that is not directly placed into the beam path well beyond the detector noise level

SummaryOptical wireless communication systems are among the most secure networking transmission technologies.3 degrees divergence angle typically used in optical wireless systems corresponds to a beam diameter of 5 meters atthe same distance.1 This wide spreading of the beam in microwave systems, combined with the fact that microwave antennas launch very high power level is the primary reason for security concerns. These features make optical wireless solutions appealing to end-users and service providers globally.5 degrees.

The direct interception of an optical wireless beam between the two remote networking locations is basically impossible because the beam typically passes through the air at an elevation well above ground level. The wavelength range around 1 micrometer translates into frequencies of several hundred terahertz (THz). This difference in frequency of operation is one of the main reasons whyoptical wireless systems belong into the equipment category of optical communication systems first rather than wireless, RF or microwave, transmission solutions. Themain reason for excluding this possibility of intrusion is the fact that light is scattered isotropicallyand statistically in different directions from the original propagation path. The small diameter of the beam of typically only a few meters in diameter at the target location is one of the reasons why it is extremely difficult to intercept the communication path of an FSO-based optical wireless system: The intruder must know the exact origination or target location of the (invisible) infrared beam and can only intercept the beam within the very narrow angleof beam propagation. As a result, the number of optical wireless system installations to for enterprise, cellular, and metropolitan area network traffic demands has increased significantly—even during the recent telecommunications sector slowdown. Unlike microwave systems, it is extremely difficult to intercept the optical wireless light beam carrying networking data because the information is not spread out in space but rather kept in a very narrow cone of light. In fact, military organizations or governmententities that rely heavily on extremely secure transmission technologies were among the earliestusers of optical wireless communication systems as a way to avoid signal interception.

Thewavelength range around 1 micrometer that is used in optical wireless transmission systems is actually the same wavelength range used in fiber-optic transmission systems. These frequencies are significantly (roughly three to four orders of magnitude) higher than the highest frequencies used in commercially available microwave communications systems operating around 40 GHz.