Engineering challenges in optical sensing
Sensors based on optical technology are revolutionizing infrastructure monitoring, industrial diagnostics, and biomedical applications. Fiber Bragg Gratings (FBG) measure temperature and strain in bridges, power plants, and aircraft. DTS (Distributed Temperature Sensing) systems monitor kilometers of pipelines with a single fiber. SPR (Surface Plasmon Resonance) biosensors detect proteins and viruses at femtomolar concentrations. LiDAR systems map surroundings with centimeter-level precision.
Each of these systems requires precise design of the optical component — the grating, fiber, plasmonic sensor, or receiver system — and verification of its response before deployment. An error in an FBG grating design translates into a temperature-measurement error in the monitored object; an error in the DTS fiber's dispersion model produces false alarms.
How does our software support design?
| Product | Role in this area |
|---|---|
 | Designing and optimizing FBG, LPG, and chirped gratings — temperature and strain sensors |
 | Analyzing sensing-fiber parameters — dispersion, attenuation, birefringence |
 | Simulating complete sensing systems — DTS, OTDR, WDM-multiplexed FBG networks |
 | Modeling plasmonic biosensors — SPR and LSPR structures in nanostructures |
a multiplexed FBG network for bridge monitoring
Design assumptions
A fiber-optic structural health monitoring system for a bridge was developed using 48 FBG (Fiber Bragg Grating) sensors connected in a WDM architecture. The network's task is to continuously measure structural strain and temperature changes at key points of the object.
FBG grating and multiplexing design
Apodized Bragg gratings operating in the C-band were designed, providing an appropriate channel spacing and reduced spectral side lobes. The grating parameters were chosen to achieve the required reflection bandwidth of about 0.2 nm and stable operation of multiple sensors on a single fiber line.
Optical interrogator testing
The readout system (interrogator) was verified under variable temperature conditions, subjecting the system to changes of around ±80°C. Stability of the Bragg wavelength shift measurement and the ability to compensate for temperature's effect on sensor readings were analyzed.
Measurement accuracy analysis
The simulations and tests carried out made it possible to assess signal distribution across the entire network, the effect of fiber attenuation, and the ability to read all channels simultaneously. The designed architecture was verified to meet the required measurement resolution of about 1°C for temperature monitoring.
Verified design
The system model allowed optimization of the number of sensors, the FBG grating parameters, and the fiber path configuration before installation on the actual structure, reducing the risk of channel interference, signal attenuation, and reliability issues across the whole monitoring network.
Frequently asked questions
Optical sensing
Does OptiGrating support simulating an FBG sensor's response to simultaneous temperature and strain changes?
Yes. OptiGrating models the FBG sensitivity matrix for both effects and allows analysis of the temperature/strain discrimination problem using gratings of different wavelengths or special dual-grating configurations.
Can a network of multiple WDM-multiplexed FBG gratings be simulated in OptiSystem?
Yes. OptiSystem includes ready-made FBG sensor blocks with a spectral response model that can be combined into WDM- or TDM-multiplexed networks, and the full interrogator system can be simulated.
Is OptiFDTD suitable for modeling SERS biosensors?
Yes. OptiFDTD supports FDTD simulation of metallic nanostructures (Au, Ag) and calculates near-field electric field enhancement — essential for designing SERS substrates and optical antennas for biosensing.
Have a specific challenge in this field?
Our engineer will reply within 1 business day and advise on tools and licensing options.
Ask an engineerLooking for OptiSystem?
Get a 14-30 day trial to test OptiSystem with full technical support during your current project.
Get OptiSystem trial