Marek Życzkowski

A Sagnac-Michelson fibre optic interferometer: Signal processing for disturbance localization

We present numerical and experimental results on a new generation fibre optic perimeter sensor based on a Sagnac and Michelson interferometers configuration. In particular, an original signal processing scheme is presented. The sensor can detect a potential intruder and determine its position along a protected zone. We propose a localization method that offers the inherent properties of both interferometers. After demodulation of the signals from both interferometers, the obtained amplitude characteristic of the Sagnac interferometer depends on a position of a disturbance along the interferometer, while amplitude characteristic of the Michelson interferometer does not depend on this position. So, quotient of both demodulated characteristics makes it possible to localize the disturbance. During investigations of a laboratory model of the sensor, it was possible to detect the position of the disturbance with a resolution of about 40 m along the 6-km-long sensor.

Data encryption of optical fibre communication using pseudo-random spatial light modulation

Abstract We propose and study a new technique for securing fibre data communication. The paper presents a method for optical encryption of information transmitted with a traditional fibre link. The encryption method uses a spatial light modulator which converts light pulses representing original data into pseudo-random patterns. A linear combination of light pulses with pseudo-random patterns provides a required encryption performance. The main element of the encryptor is the spatial light modulator which comprises a matrix of cells selectively transmitting or blocking the light beam depending on the pseudo-random configuration of cells. The encrypted information is transmitted through the optical fibre. The decryption process relies on a computational solving of linear program or greedy pursuit. We present a brief description of the method, theoretical analysis and results of numerical simulation. A physical model concept of the method is also presented.

Harmless screening of humans for the detection of concealed objects

Multispectral screening systems are becoming more popular because of a wide range of applications. Terahertz and infrared radiation have unique properties applicable to the field of surveillance and security systems. One of the most significant applications of multispectral screening systems is the prevention of terrorist attacks. Visual detection of objects hidden under clothing of a person is one of the most challenging problems of threat detection. There are many solutions to the problem; however, the most effective utilize multispectral surveillance imagers. We investigate the possibility of harmlessly detecting objects covered by various types of clothing in three spectrums – visible, infrared and terahertz. The terahertz range of electromagnetic radiation has considerable potential to detect hidden objects because it penetrates clothes. The infrared imagers are also very useful in searching for concealed objects because infrared cameras can detect small temperature differences on the surface of clothing. Radiation from these three ranges is harmless to humans. We present the detection methodology using infrared and terahertz imagers as complementary sensors to provide image data for a multispectral threat detection system. Possible ways of using the results are also presented.

Optical fiber sensors as the primary element in the protection of critical infrastructure especially in optoelectronic transmission lines

The security systems of the wide area objects are dominated by fiber optic sensors, used primarily to perimeter protection as well as to the protection of vast objects such as pipelines. Critical infrastructure objects are not only industrial facilities but also the transmission lines. Authors present the sensor systems compared to sensors for extensive object security currently available on the market. The designed systems, such as double interferometer system as well as more and more popular QKD systems are sensors with distributed sensing field. These systems, described by authors in many publications, are excellent solutions for the protection of wide area infrastructural objects. Presented fiber sensors, besides sabotage detection also offer the possibility of locating the disturbance along many kilometers of the zone. The solution presented in this paper was designed to adapt well known solutions to the physical protection of the transmission line without interfering with the transmitted data. According to the knowledge of potential threats of fiber optic telecommunications, the authors present methods of protecting fiber optics telecommunication cable, and present their own solutions and describe their application possibilities.

Multisensor system for the protection of a critical harbour infrastructure

The critical facilities within a harbour area require special protection, including security systems capable of monitoring both surface and underwater areas. The paper presents the concept of a multisensor security system for harbour protection, capable of complex monitoring of selected critical resources. The proposed system consists of a command centre and several different sensors deployed in key areas, providing effective protection from penetration from land and sea, with special attention focused on the monitoring of the underwater zone. The initial project of such systems was presented, its configuration and initial tests of the selected components. The protection of a surface area is based on medium-range radar, LLTV, and infrared cameras. The protection of an underwater zone is based on sonar, acoustic, and magnetic barriers. Both systems are combined into one, integrated multisensor monitoring system. Some results of theoretical analyses based on the detection of a fast and small surface were presented.

Mobile border verification of travellers based on fingerprints: experimental studies

The paper describes the results of experimental research on the mobile verification of travellers based on fingerprints. Three-day tests were carried out at the border crossing in Terespol, Poland. The developed system automatically acquires personal and biometric data (fingerprints) from the Polish biometric passport, determines their quality and compares with the live data collected from the traveller. In addition, the system measures the time of individual stages of the process and determines total transaction time. For total number of correctly scanned travellers equal to 128, false acceptance rate equals to 0, while rejection rate is less than 1%. The average transition time of border check was 37 seconds.

Encryption key generator based on passive optical elements

This article presents the concept of the encryption key generator on the basis of passive fiber optic components. Quantum random number generators (QRNG) are used to obtain the random number sequences used to securely encode information transmitted in the fiber track. The authors propose a different approach than the currently used random number generators based on beam splitting element, namely the construction of this type of system based on passive fiber optic components with the use of single-photon generation. The article presents the analysis of the generation of random number sequences as well as independently developed simulator generation of random sequences. It also contains a description of selected items and the reasons for selection as well as patterns of accomplished setup made in the Security Systems Group in Institute of Optoelectronics. The methodology of measuring generation randomness of quantum random number generator is described here, also certified system made by ID Quantique and propretiary solution is compared and results of measurements of this comparison are presented. The work also includes tests of the certified system Quantis by IDQ company and the system made by a team in terms of randomness generated within. These tests are important from the point of view of the certification of a generator system and assign it to the appropriate safety class. The measurement results are contained in the article.

Safety of data exchange in pulse interferometer

Current solutions used for protection of information transmitted in fibre optic networks are based on direct detection of fibre optic cable eavesdropping and encryption of transmitted information. Protection of fibre optic cables from physical intrusion in to the transmission channel is realized on dark optical fibres, not used in the transmission of information. Security of encrypted information is based on the assumption of limited computing power used for cryptanalysis, what with the introduction of operating quantum computers will cease to apply. So ideal solution for information protection is physical it coding that makes eavesdropping near to impossible, in the same time allows of constant monitoring of fibre physical integrity. The article describes the construction and principle of operation used in fibre optic pulse interferometer, that allows to detect mechanical disorders of fibre optic transmission line with simultaneous transmission of information. Operation of the system relies on encoding information in phase of optical radiation pulses and for monitoring the status of the transmission line by analysis polarization of radiation in interferometer. System configuration provides stabilized work of pulse interferometer over several kilometres, under varying environmental conditions. Unique capabilities of detection system enable the use of two independent criteria for alarm signal excitation. The aim of the study was to determine the security degree provided by system to protection of transmitted information in proposed arrangement.

Laboratory and field tests of the Active Composite Fence with integrated fiber optic modalmetric sensor and electromagnetic sensor

This paper presents tests of the active composite fence with razor tape module. Due to application of electro-magnetic and optical fiber sensors the fence becomes actively protected. This type of solution may be used to detect violations of peripheral areas [1]. Due to using composite materials the fence is lighter, cheaper and resistant to environmental conditions (including corrosion). What is the most important the composite fence system is transparent to electromagnetic waves. Another advantage of using composite material is the possibility of integration the fiber optic and electro-magnetic cable in the structure of the fence [2]. The durability of a composite is comparable to a standard metal fence. The paper presents test results of the sensors placed on the composite fence. This type of the fence system protection with alarm sensors integrated in its structure is unique in the world scale. Performed tests consisted of laboratory and field tests of modalmetric fiber optic sensor itself, laboratory and field tests of electro-magnetic sensor itself and field tests of both sensors combined. During the laboratory tests an electrodynamic shaker was used to excite the modalmetric sensor to an alarm state. Its excitation distance decreases with the frequency growth. The tests were made for different frequencies and different forces to imitate different fence violation e.g. climbing on it, cutting it or walking along it.

Single photon fiber optic sensor in detection of fiber optic telecommunication line tapping

This article presents the single photon fiber optic sensor for detecting interferences of the transmission line. With the growing popularity of the use of fiber optic communication systems, there is a need to protect transmission lines against unauthorized interference and data interception. Classical Quantum Key Distribution (QKD) allows to transfer quantum key and interrupt transmission when it detects interference. The use of proven as safe protocols BB84 in conjunction with currently used encryption techniques provide better data safety. However, due to lack of evidence on the safety of transmission using commercial QKD systems, their apply to the protection of classified information is currently impossible. Support these assumptions are carried out so far successful attacks on QKD systems. These statements do not mean impossibility of implementing these systems for the protection of classified information in the future. Our team proposes a solution consisting in transmitting information in fiber optic track with simultaneous implementation of a single photon sensor, developmentally impaired with the location of the interference place. The greatest yield of this method is to detect the intruder, who is unaware of its detection. To optimize and accelerate the testing, a simulation program that allows you to adjust the operating parameters of the sensor system and verification of performance of laboratory systems has been developed. Execution of simulation, helps in the selection of appropriate elements of the actual configuration and in comparison to obtained results. This work contains the results of the test operation of the system for disorders of mechanical and manual as well as performed simulations.