Fiber Optics is a sub working field of the optics. While the optics is the field of light, fiber optics concerned with optical phenomenon in Glass Fibers only. Fiber means threads and when we called fiber optics its usually glass threads that can enable the light can pass through.
Optical Time Domain Reflectometry
Optical Time Domain Reflectometry is a device that measures many features in Fiber Optic Cables. They mostly uses to measuring cable conditions and problems. If there are any transmission related problems in Fiber Optic Cables, OTDR can find it.
Distributed Acoustic Sensing
Distributed Acoustic Sensing (DAS) are type of sensing that can detect acoustic signals. Sound waves are the most common example of acoustic waves.
The word Laser is an acronym for a longer sentence. It is short for Light Amplification by Stimulated Emission of Radiation. DAS systems and many other systems use Laser technologies.