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CRD Sensing


The increasing need of measuring chemical, physical or biological signals in remote and hazard environments has prompted the development of new technologies for optical sensing.

CRD Sensing is a new optical fibre configuration that makes possible remote sensing using commercial equipment such as the OTDR, enabling a more efficient, compact and easy handling sensing system.

Challenge | Opportunity

Current solutions for enabling remote sensing using CRD technique comprises the inclusion of optical devices such as the optical circulator.  However, such feature leads to high signal losses, what is critical when data is being measured at long distances. Further, conventional CRD configuration needs two fibres paths, one for signal transmission and other for signal reception, which is not an attractive solution for remote sensing applications.

The inclusion of commercial equipment, namely the optical time-domain reflectometer (OTDR), and the conversion of the conventional ring CRD configuration into a linear cavity is a new opportunity to remote sensing in a network system.

Main Advantages

- Allows the use of OTDR in a new set of scenarios and applications;
- Operates with any intensity-based optical fibre sensor;
- Compact configuration to keep OTDRs’ portability;
- Twice sensitivity due to its linear cavity;
- Ready to monitor physical and biological parameters, either in liquid or gas medium.


- Environmental control;
- Climate change monitoring;
- Structural integrity evaluation;
- Underwater applications;
- Remote monitoring in radioactive environments.

  • Technology Reference

  • Commercial Rights

  • Development Stage

    Lab prototype (TRL 3-4)
  • Further Information

    <p><a href="">EP3665452A1</a> </p> <p><a href="">JP2020530561A</a> </p> <p><a href="">US2020182717A1</a> </p> <p> </p> <p> </p>
  • IPR Status

    Patent Pending
  • Licensing Availability

  • Industrial Categories

    Information and Communication, Environment
  • Tags

    Underwater communication