Multimode fiber Φ-OTDR with holographic demodulation

Self-Mixing Demodulation for Coherent Phase-Sensitive OTDR System

Phase-sensitive optical time domain reflectometry (Ф-OTDR) attracts much attention due to its capability of telling the type and position of an intrusion simultaneously. In recent decades, coherent Ф-OTDR has been demonstrated to realize long-distance detection. For coherent Ф-OTDR, there are three typical demodulation schemes in the reported studies. However, they still cannot realize real-tim...

Mach-Zehnder Interferometer Based on All-fiber Multimode Interference Device for DPSK Signal Demodulation

Differential Phase Shift Keying (DPSK) modulation format has been shown as a robust solution for next-generation optical transmission systems. One key device enabling such systems is the delay interferometer, converting the signal phase information into intensity modulation to be detected by the photodiodes. Usually, Mach-Zehnder interferometer (MZI) is used for demodulating DPSK signals. In th...

Fiber Measurement Technique Based on OTDR

Mode multiplexing and holographic demultiplexing communication channels on a multimode fiber.

Spatial mode multiplexing is used to transmit several communication channels on a single multimode optical fiber. Each channel is encoded by an orthogonal pattern produced by a spatial light modulator. A photorefractive medium holographically decodes the output speckle pattern at a receiver station. We demonstrate ring and star architectures for interconnection networks. Typical cross-talk-to-s...

Sensing of Multimode Optic-Fiber Dynamic Strains by Using Self-Adaptive Holographic Interferometers

Two-wave mixing (TWM) via a dynamic hologram recorded in a photorefractive crystal allows the implementation of adaptive interferometers. These interferometers can achieve high sensitivity of detection of phase shifts under unstable environmental conditions even when phase shifts are encrypted in speckled waves such as those reflected from rough surfaces or emerging from multimode optical fiber...