Liquid crystal based active wavelength filter for phase-sensitive optical time domain reflectometry.

This study proposes a liquid-crystal-based active wavelength filter for phase-sensitive optical time domain reflectometry to mitigate the amplified spontaneous emission (ASE) noise and accurately match the passband with the light source. The validity of the proposed system was verified using comparative experiments with conventional passive optical filters. The experiment showed an increase in signal-to-noise ratio (SNR) of up to 2.

Tracking Efficiency Improvement According to Incident Beam Size in QPD-Based PAT System for Common Path-Based Full-Duplex FSO Terminals.

Free space optical (FSO) communication can support various unmanned aerial vehicles' (UAVs) applications that require large capacity data transmission. In order to perform FSO communication between two terminals, it is essential to employ a pointing, acquisition, and tracking (PAT) system with an efficient and optimal performance. We report on the development of a common optical-path-based FSO communication system, tailored for applications in UAVs.

A Sensing Device with the Optical Temperature Sensors-Based Quad-RX Module and a Security Module.

In this paper, we present a sensing device with the optical temperature sensors-based quad receiver (Quad-RX) module and a security module. In addition, in order to prevent cyberattacks on critical national infrastructures and key facilities, we implemented symmetric-key and secure hash algorithm-based hardware security modules in the key elements of the sensing device. A preliminary test was conducted prior to a field trial to verify the performance of the developed sensing device.