What FBG sensors are and why 2026 is a turning point
Fiber Bragg Grating sensors are photonic devices inscribed in optical fiber cores that reflect specific wavelengths in response to physical stimuli — primarily strain, temperature, and pressure — making them foundational to precision structural and industrial monitoring. The technology is gaining renewed urgency in 2026 as photonic integrated circuits, multiplexed sensing architectures, and harsh-environment deployments converge to expand FBG applicability from civil infrastructure to brake-by-wire automotive systems and minimally invasive medical devices.
FBG sensors operate by detecting shifts in the Bragg reflection wavelength of a periodic refractive-index modulation inscribed along an optical fiber core. External stimuli — mechanical strain, temperature change, pressure, or erosion — alter the grating period or effective refractive index, shifting the reflected spectrum. Within this patent dataset, three primary sub-domains are evident: point FBG sensing (discrete gratings at known positions), multiplexed and array FBG sensing (multiple gratings along a single fiber exploiting wavelength-division or time-division multiplexing), and birefringent FBG sensing (polarization-maintaining fibers where birefringence splits each Bragg peak into two orthogonal polarization components).
In a polarization-maintaining fiber, birefringence splits each Bragg reflection into two orthogonally polarized spectral peaks centered at different frequencies (ω₁, ω₂). A photonic integrated circuit performs polarization beam splitting followed by heterodyne mixing with a local oscillator, generating RF beat signals. This enables simultaneous multi-axis strain and temperature measurement with high sensitivity — a hallmark of Brembo’s most recent patent filings.
Complementary distributed sensing technologies — Brillouin scattering and Rayleigh backscatter — appear in the dataset but are distinct from point-FBG approaches and are treated separately where relevant. According to WIPO, photonic sensing is among the fastest-growing sub-categories within optical technology patent filings globally, a trend this FBG-specific dataset reflects at the application level.
Fiber Bragg Grating sensors are photonic devices inscribed in optical fiber cores that reflect specific wavelengths in response to physical stimuli — primarily strain, temperature, and pressure — and are used for precision structural and industrial monitoring across automotive, medical, energy, and infrastructure sectors.
A 27-year innovation timeline: from foundational demodulation to PIC integration
Patent publication dates in the FBG dataset span from 1999 to March 2026, revealing a multi-decade evolution across four distinct phases. Each phase reflects a qualitative shift in what engineers were trying to solve — from basic wavelength readout to on-chip miniaturisation.
The foundational phase (1999–2005) established core wavelength demodulation architectures. TRW Automotive US LLC filed on FBG inscription control (1999, KR); Toshiba Corporation filed on wavelength-scanning tunable-filter interrogators (2003, 2005, JP); FiberPro Inc. filed on tunable-laser FBG sensor systems with wavelength stabilisation feedback (2005, KR); and Weatherford/Lamb Incorporated’s broadband readout grating mixing system (2003, JP) represents early commercial interrogator design.
The maturation and multiplexing phase (2010–2015) saw Fujikura Ltd. introduce optical marking sections for high-spatial-resolution position identification within FBG arrays (2010–2014, JP), Siemens Energy deploy multiplexed FBG arrays for crack and wear detection (2013–2014, KR/JP), and Koninklijke Philips N.V. begin filing on continuous multi-core FBG shape-sensing fibers for medical applications (2015, JP).
Advanced interrogation and automotive integration (2019–2023) brought Brembo S.p.A. to the fore as the dominant recent filer, introducing tunable-bandpass-filter FBG interrogation for brake system integration (2021, IT/EP; 2022, KR/JP) and birefringent FBG heterodyne interrogation via photonic integrated circuits (2023, KR/BR). The Commissariat à l’Énergie Atomique et aux Énergies Alternatives (CEA) also patented variable-pitch Bragg grating erosion sensors for harsh environments during this period (2021–2022, FR).
“Brembo’s Bi-FBG heterodyne method received an active EP grant in October 2024 — the most technically advanced interrogation patent in the dataset, combining polarization-maintaining fiber, photonic integrated circuit demodulation, and automotive-grade packaging in a single claim family.”
The frontier phase (2024–2026) clusters around photonic integration, multi-parameter fiber shape sensing, and adaptive interrogation. Philips filed updated shape-sensing FBG patents in 2024 (JP/CN); Nanyang Technological University (Singapore) filed on an optical power-modulated FBG sensitivity-control sensor system (2025, CN); NEC Corporation filed on distributed optical fiber fracture sensing (2026, JP); and a Japanese foundation filed on FBG-based ultrasonic sensing at temperatures up to 800°C (2024, JP).
FBG sensor patent publication dates in the PatSnap dataset span from 1999 to March 2026, with the densest filing activity occurring in the 2019–2023 period, driven primarily by Brembo S.p.A.’s automotive braking system patent portfolio expansion across JP, KR, IT, EP, and BR jurisdictions.
Four interrogation clusters driving the current FBG patent landscape
FBG interrogation — the method by which a wavelength shift is converted into a measurable signal — is the core technical battleground in this dataset. Four distinct architectural clusters emerge, each with different cost, sensitivity, and integration profiles.
Cluster 1: Tunable Filter and Edge-Filter Interrogation
The most prevalent architectural approach uses broadband illumination of the FBG sensor and wavelength-selective detection via tunable optical bandpass filters (BPF) or edge filters. The FBG’s reflected spectrum is passed through a BPF fixed at the nominal Bragg wavelength; complementary output ports produce differential electrical signals that encode wavelength shift as intensity ratio. This avoids the cost of a full optical spectrum analyser. Brembo S.p.A. holds both the 2024 EP-granted and 2026 JP-active patents in this cluster.
Cluster 2: Birefringent FBG with Heterodyne PIC Detection
A more recent and technically advanced cluster involves polarization-maintaining fibers where birefringence splits each Bragg reflection into two orthogonally polarized spectral peaks. A photonic integrated circuit performs polarization beam splitting followed by heterodyne mixing of each component with a local oscillator, generating RF beat signals. This approach yields simultaneous multi-axis strain and temperature information with high sensitivity. Brembo S.p.A. holds the dominant position in this cluster across EP (2024 grant), BR (2023), and JP (2025 active) jurisdictions.
Map the full FBG interrogation patent landscape with PatSnap Eureka’s AI-powered analysis tools.
Explore FBG Patents in PatSnap Eureka →Cluster 3: Multiplexed FBG Arrays with Spatial Position Identification
Multiple FBG elements — either at distinct Bragg wavelengths (wavelength-division multiplexing) or identical weak gratings with optical gain compensation — are deployed along a single fiber to perform distributed point sensing. Fujikura Ltd.’s optical marking sections (grating-free fiber segments 0.6–2 mm long) act as positional reference anchors enabling high-spatial-resolution addressing of each sensing element. Busan National University’s identical-weak-FBG system amplifies chromatic optical path differences to distinguish gratings sharing the same Bragg wavelength.
Cluster 4: Multi-Core Continuous FBG Shape Sensing
For 3D position and shape reconstruction, multiple fiber cores each bearing a continuous or quasi-continuous FBG are deployed along a flexible catheter, guidewire, or instrument. A reflectometer measures strain at dense sampling points; a processor reconstructs 3D shape from differential curvature across cores. Koninklijke Philips N.V. has developed this architecture extensively for medical interventional devices, with filings spanning 2015 to 2024 in JP, CN, and BR. According to IEEE, multi-core fiber shape sensing is among the most active research areas in photonic sensing, reflecting the clinical demand for real-time catheter tracking.
Brembo S.p.A.’s birefringent FBG heterodyne detection patent, which uses a photonic integrated circuit to perform polarization beam splitting and heterodyne mixing of two orthogonally polarized Bragg reflection peaks, received an active European Patent (EP) grant in October 2024.
Application domains: automotive, medical, energy, and beyond
FBG sensors have diversified well beyond civil structural monitoring. The patent dataset reveals six distinct application domains, each with a different maturity profile and competitive concentration.
Automotive and Brake Systems
The most intensively patented application domain in this dataset is FBG-instrumented vehicle braking systems. Brembo S.p.A. holds a family of patents covering FBG strain sensors embedded in brake calipers, brake pads, and washer devices at caliper-to-support interfaces to measure clamping force, braking torque, and tangential/normal pad forces. This enables closed-loop brake-by-wire control — a critical capability as the automotive industry transitions to electrified and autonomous platforms. Brembo’s filings in this sub-domain extend from 2021 through a 2026 KR patent on braking torque determination.
Medical and Surgical Devices
Multi-core shape-sensing FBG fibers enable real-time 3D position tracking of catheters, guidewires, and endoscopes during minimally invasive procedures. Koninklijke Philips N.V. has developed this architecture continuously from 2015 to 2024 in JP, CN, and BR. The 2024 filings refine the single-reflection-peak-per-grating architecture (differing peak wavelengths along each core) to improve phase tracking accuracy and reduce positional errors in optical shape sensing for interventional devices. Research published through Nature has documented the clinical advantages of FBG-based shape sensing over electromagnetic tracking for catheter navigation, including immunity to electromagnetic interference in operating theatre environments.
Energy and Structural Health Monitoring
FBG multiplexed arrays are deployed for crack detection in turbines and structural components, wind blade monitoring, and harsh-environment erosion sensing. Siemens Energy’s multiplexed optical fiber crack sensor (2013, KR) and Vestas Wind Systems’ optical fiber grating sensor system (2019, ES) represent this domain. CEA’s variable-pitch Bragg grating erosion sensor for harsh environments (2022, FR) extends the application to environments where conventional sensors degrade rapidly — nuclear plant internals and high-velocity fluid erosion zones.
Oil and Gas / Downhole Sensing
Downhole FBG interrogators are co-deployed in the wellbore with the sensing fiber to avoid long-distance signal degradation. Baker Hughes holds two records in BR covering downhole FBG interrogation methods and apparatus. The co-location of interrogator and sensing fiber in the wellbore addresses the signal attenuation challenge inherent in kilometre-scale fiber deployments.
Rail and Transportation Infrastructure
FBG fatigue sensors in V-type cross geometry are configured on sensor plates fixed to rail sections for axle-counting and rail force monitoring. Thales Management & Services Deutschland GmbH holds EP and ES records for a fiber optic sensor unit and shaft counting device (2022).
Security and Perimeter Monitoring
Taut fiber perimeters with FBG stretch detection enable intrusion detection. A reference FBG with longer center wavelength detects the shift upon perimeter breach. A 2013 US patent by independent inventor Jason Bentley Lamont covers this application — the sole US-jurisdiction record in the dataset.
Brembo S.p.A.’s brake system FBG portfolio — spanning caliper-embedded sensors, pad-embedded sensors, and caliper-to-support interface torque sensing — accounts for the largest single-assignee, single-application concentration in the dataset. R&D teams at automotive tier-1 suppliers should map freedom-to-operate carefully around Brembo’s 2021–2026 filings before instrumenting brake components with FBG sensors.
Geographic and assignee concentration: Japan, Korea, and the Brembo effect
Japan and Korea dominate FBG patent prosecution in this dataset — not primarily because of domestic Japanese or Korean FBG innovation, but because European and US originators (Brembo, Philips, Siemens) have chosen those registers as priority markets for their IP.
Among the retrieved results, the following assignee patterns are evident. Brembo S.p.A. (Italy) is the single most active assignee, with at least 12 distinct patent records spanning JP, KR, IT, EP, and BR jurisdictions — all relating to FBG integration in automotive braking systems and advanced interrogation methods. Koninklijke Philips N.V. (Netherlands) holds at least 5 records across JP, CN, and BR, focused on multi-core continuous FBG for medical shape sensing. Busan National University Industry-University Cooperation Foundation (South Korea) holds 3 KR records covering multiplexed identical-FBG arrays — a notable academic-origin IP cluster. Fujikura Ltd. (Japan) holds 3 JP records on spatial-resolution-enhanced FBG sensor arrays. Kabushiki Kaisha Toshiba (Japan) holds 5 JP records, primarily foundational interrogation instruments from 2003–2010, now largely inactive. Siemens Energy, Incorporated (US) holds 2 records (KR/JP) on multiplexed FBG crack and wear sensors. CEA (France) holds 2 FR records on variable-pitch FBG erosion sensors — the sole French jurisdiction filer in this dataset. Baker Hughes (US) holds 2 BR records on downhole FBG interrogation.
As EPO data on photonic technology trends confirms, European originators increasingly use Asian prosecution registers as primary commercial battlegrounds — a pattern clearly visible in Brembo and Philips’ JP-heavy filing strategies within this dataset.
Assess assignee concentration and freedom-to-operate risk in FBG sensor IP with PatSnap Eureka.
Analyse FBG Assignees in PatSnap Eureka →Five emerging directions in FBG sensing (2024–2026)
The most recent filings in the dataset (2024–2026) cluster around five directional signals that indicate where the technology frontier is moving and where IP whitespace may exist.
1. Photonic Integrated Circuit (PIC) Interrogation
Brembo’s 2024 EP-granted and 2025 JP-active patents on Bi-FBG heterodyne detection via on-chip PIC represent the leading edge of miniaturised, high-bandwidth interrogation. The shift from free-space or fiber-based demodulators to silicon-photonics PICs suggests a pathway to compact, embedded automotive sensor modules. Teams that can miniaturise FBG interrogation onto standard silicon photonics foundry platforms will unlock automotive, aerospace, and wearable sensing markets where size and cost dominate.
2. Adjustable Sensitivity and Center-Wavelength Control
Novel FBG probe designs allowing mechanical pre-tensioning or compression of the grating via a docking-body/adjustment-body mechanism enable active tuning of the sensor’s center wavelength and dynamic range in the field. This addresses longstanding limitations in fixed-wavelength multiplexed arrays. Both a Korean independent inventor (2025, KR) and Nanyang Technological University (2025, CN) filed in this direction within the same year.
3. High-Temperature Ultrasonic Structural Monitoring
FBG arrays are being configured to detect Lamb waves and acoustic emission (AE) in structures operating at 200°C–800°C — a regime where conventional piezoelectric transducers fail. A 2024 Japanese foundation patent covers this application, targeting aerospace composites and nuclear reactor internals. CEA’s variable-pitch erosion sensor (FR) and this high-temperature ultrasonic system represent a thin IP frontier in demanding environments — an accessible innovation space for materials-focused R&D, particularly around regenerated FBGs and sapphire fiber gratings, which do not appear prominently in this dataset.
4. Continuous Multi-Core FBG for Medical Shape Sensing Refinement
Philips’ 2024 filings refine the single-reflection-peak-per-grating architecture (differing peak wavelengths along each core) to improve phase tracking accuracy and reduce positional errors in optical shape sensing for interventional devices. Koninklijke Philips N.V.’s continuous-FBG multi-core fiber patents across JP, CN, and BR constitute a substantial barrier for entrants developing catheter or guidewire shape sensing. New approaches differentiating on grating inscription method, core count, or interrogation algorithm may find whitespace.
5. Distributed Fiber Break and Fault Detection
NEC Corporation’s 2026-dated patent on continuous distal-end position monitoring enables autonomous detection of fiber fracture in deployed sensing infrastructure, signalling a move toward self-diagnosing fiber sensor networks. This is the most recent filing in the dataset and suggests a convergence between FBG point sensing and fully distributed fiber monitoring — a direction consistent with the broader trend toward autonomous infrastructure management documented by OECD in its infrastructure digitalisation reports.
FBG arrays configured to detect Lamb waves and acoustic emission in structures operating at temperatures from 200°C up to 800°C are emerging as a new patent cluster in the 2024–2026 dataset, targeting aerospace composites and nuclear reactor internals where conventional piezoelectric transducers cannot operate reliably.
Strategic implications for R&D and IP teams
The patent landscape described above carries specific, actionable implications for teams working in or adjacent to FBG sensor technology. Five strategic observations emerge directly from the dataset.
Brembo’s IP position in automotive FBG sensing is strong and cross-jurisdictional. With active grants in EP, KR, and JP covering both tunable-BPF and Bi-FBG heterodyne interrogation for braking systems, Brembo has constructed a layered portfolio that will constrain competitors attempting to instrument brake calipers or pads with FBG sensors without licensing. R&D teams in automotive tier-1 suppliers should map freedom-to-operate carefully around Brembo’s 2021–2026 filings before committing to FBG-based brake force measurement architectures.
Photonic integration is the interrogation bottleneck to solve. The shift from benchtop optical interrogators to PIC-embedded demodulation (Brembo’s heterodyne PIC approach) is the most technically significant direction in this dataset. Teams that can achieve this miniaturisation on standard silicon photonics foundry platforms will unlock automotive, aerospace, and wearable sensing markets where size and cost dominate. This is an area where collaboration with photonics foundries and academic PIC research groups may accelerate time-to-IP.
Multi-core shape sensing remains a Philips stronghold. Koninklijke Philips N.V.’s continuous-FBG multi-core fiber patents across JP, CN, and BR constitute a substantial barrier for entrants developing catheter or guidewire shape sensing. New approaches differentiating on grating inscription method, core count, or interrogation algorithm may find whitespace outside the current claim boundaries.
High-temperature and harsh-environment FBG is under-IP’d. CEA’s variable-pitch erosion sensor (FR) and the Japanese foundation’s 800°C ultrasonic sensing system represent a thin IP frontier in demanding environments — nuclear, aerospace, high-velocity erosion. This is an accessible innovation space for materials-focused R&D, particularly around regenerated FBGs and sapphire fiber gratings, which do not appear prominently in this dataset.
Japan and Korea are the dominant FBG prosecution jurisdictions. Any global IP strategy for FBG sensor products must prioritise JP and KR prosecution, given the concentration of both domestic originators (Fujikura, Toshiba, NEC, Busan University) and foreign filers (Brembo, Philips, Siemens) in those registers. Failure to prosecute in JP and KR leaves significant commercial territory unprotected. Teams can explore the full PatSnap platform for jurisdiction-specific prosecution analytics, or use PatSnap Insights for ongoing technology landscape updates.
“High-temperature and harsh-environment FBG sensing — covering operating regimes up to 800°C where piezoelectric transducers fail — represents a thin IP frontier that is accessible to materials-focused R&D teams, particularly those working with regenerated FBGs and sapphire fiber gratings.”
This landscape is derived from a limited set of patent and literature records retrieved across targeted searches. It represents a snapshot of innovation signals within this dataset only and should not be interpreted as a comprehensive view of the full FBG sensor industry. Actual filing volumes and assignee rankings may differ in a full global patent database analysis.