Latest Research News on Optical Fiber : May 21

[1] Optical Fiber Communications

Optical fibers are used extensively for data transmission systems because of their dielectric nature and their large information‐carrying capacity. Network architectures using multiple wavelength channels per optical fiber are utilized in local, metropolitan, or wide‐area applications to connect thousands of users having a wide range of transmission capacities and speeds. A powerful aspect of an optical communication link is that many different wavelengths can be sent along a fiber simultaneously in the 1300‐to‐1600‐ nm spectrum. The technology of combining a number of wavelengths onto the same fiber is known as wavelength division multiplexing (WDM). The concept of WDM used in conjunction with optical amplifiers has resulted in communication links that allow rapid communications between users in countries all over the world.

[2] Optical Fiber Sensor Technology

The current state of the art of optical fiber sensors is reviewed. The principles of operation are detailed and the various types of fiber sensors are outlined. Achievable performance and limitations are discussed and a description of technology used to fabricate the sensor is presented. The characteristics of acoustic, magnetic, gyro, laser diode, and other sensors are described. Trends in the development of this sensor technology and expected application areas are briefly outlined.

[3] Review of the present status of optical fiber sensors

The current status of optical fiber sensors is reviewed. The optical fiber sensors have certain advantages that include immunity to electromagnetic interference, lightweight, small size, high sensitivity, large bandwidth, and ease in implementing multiplexed or distributed sensors. Strain, temperature and pressure are the most widely studied measurands and the fiber grating sensor represents the most widely studied technology for optical fiber sensors. Fiber-optic gyroscopes and fiber-optic current sensors are good examples of rather mature and commercialized optical fiber sensor technologies. In this paper, among the various fiber-optic sensor technologies, especially, technologies such as fiber grating sensors, fiber-optic gyroscopes, and fiber-optic current sensors are discussed with emphasis on the principles and current status. Today, some success has been found in the commercialization of optical fiber sensors. However, in various fields they still suffer from competition with other mature sensor technologies. However, new ideas are being continuously developed and tested not only for the traditional measurands but also for new applications.

[4] A Simple Relative Humidity Sensor Employing Optical Fiber Coated with Lithium Chloride

A simple optical fiber relative humidity sensor was fabricated using a lithium chloride film coated on the distal end of sensing fiber. The sensing element, lithium chloride film whose refractive index is sensitive to moisture, thereby changes the reflected light intensity of the sensing end. By monitoring the change of reflected light intensity under different RH levels, the information about RH of the environment can be obtained. A difference of up to 0.64uW of the reflected optical power is observed when RH changes from 11 to 75%. The LiCl-based sensor has a sensitivity of about 0.01uW/%RH with a slope linearity of more than 99.8%. The experimental setup is simple and easy to handle. The results demonstrate that LiCl-based optical fiber sensor is sensitive, economical, flexible, and fast response, has the potential of remote on-line monitoring humidity.

[5] Optical Time Domain Reflectometer Assessment of Attenuation in Fiber Optics Communication System

Attenuation is an undesirable factor that weakens the strength of signal as it travels down fiber optics. Attenuation level in every fiber communication link must be kept at its tolerable range in order to maintain good signal transmission. When the level of attenuation in a link is higher than the acceptable tolerance value, the transmission suffers some setbacks such as loss of signal, freezing of signal etc. An optoelectronic device, Optical Time Domain Reflectometer (OTDR) was used in the measurement of attenuations in the single-mode fiber using the uni-directional technique. It is a convenient and powerful tool for rapidly assessing attenuation behavior in optical fibers. It combines a detector and laser source to provide an inside view of the fiber link described by a trace. The injected light pulse from the laser source is received at the detector. OTDR traces were produced in accordance with the light pulses received. From these traces, the attenuation levels for the different fiber cores were obtained. An average attenuation limit of 0.188 dB/km and average section loss of 0.3dB for 1550 nm wavelength window over the span length of 1597.35 m were achieved which are within the acceptable standard range of 0.20 dB/km to 0.30 dB/km.

Reference

[1] Keiser, G., 2003. Optical fiber communications. Wiley encyclopedia of telecommunications.

[2] Giallorenzi, T.G., Bucaro, J.A., Dandridge, A., Sigel, G.H., Cole, J.H., Rashleigh, S.C. and Priest, R.G., 1982. Optical fiber sensor technology. IEEE transactions on microwave theory and techniques30(4), pp.472-511.

[3] Lee, B., 2003. Review of the present status of optical fiber sensors. Optical fiber technology9(2), pp.57-79.

[4] Zhang, B.K. and Tan, C.H., 2017. A Simple Relative Humidity Sensor Employing Optical Fiber Coated with Lithium Chloride. Physical Science International Journal, pp.1-6.

[5] Ilouno, J. and Audu, I.J., 2018. Optical Time Domain Reflectometer Assessment of Attenuation in Fiber Optics Communication System. Journal of Engineering Research and Reports, pp.1-6.

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