Heracle High-Temperature Gold-Coated Step-Index Multimode Optical Fiber

Overview

The Heracle High-Temperature Gold-Coated Step-Index Multimode Optical Fiber is engineered for optical signal transmission and sensing under extreme environmental conditions where conventional polymer-coated fibers fail. Based on a fused silica core and fluorine-doped silica cladding, this step-index multimode (SIMM) fiber features a continuous, hermetic 24K gold coating applied via high-vacuum physical vapor deposition (PVD). The gold layer serves not only as a thermal and chemical barrier but also provides electrical conductivity—enabling direct metallurgical bonding (e.g., laser welding, resistance brazing, or eutectic soldering) to metal feedthroughs, vacuum flanges, or semiconductor laser diode packages. Its design adheres to the fundamental principles of waveguide optics while extending operational robustness far beyond standard telecom-grade or laboratory-grade fibers. This fiber is explicitly intended for use in ultra-high vacuum (UHV), radiation-intensive, chemically aggressive, and thermally cycling environments—where dimensional stability, low outgassing, and mechanical integrity must be maintained across decades of service life.

Key Features

• Continuous 99.99% pure gold coating deposited under controlled vacuum conditions, ensuring uniform thickness, minimal interfacial defects, and no organic contaminants.
• Ultra-broad operating temperature range: −269 °C (liquid helium) to +700 °C (continuous exposure), validated per ASTM E1113 and IEC 60794-1-2-E1.
• Low hydroxyl (OH⁻) content variant optimized for visible-to-infrared (VIS/IR) transmission (350–2200 nm); high-OH variant optimized for ultraviolet-to-visible (UV/VIS) applications (190–800 nm).
• Hermetically sealed structure eliminates moisture ingress and suppresses stress corrosion cracking—critical for long-term reliability in humid or corrosive atmospheres.
• Outgassing rate <1×10⁻⁹ g/(cm²·s) at 120 °C, fully compliant with NASA SP-R-0022A and ESA ECSS-Q-ST-70-02C for space-grade vacuum compatibility.
• Proof-tested to ≥100 kpsi (≥690 MPa) and median tensile strength ≥3.3 GPa, exceeding MIL-STD-883H Method 2011.9 requirements for ruggedized photonic components.

Sample Compatibility & Compliance

This fiber is compatible with standard FC/PC, SMA905, and custom metal-encapsulated connectors. Its gold surface allows direct integration into stainless steel, Kovar, or Invar-based vacuum feedthrough assemblies without intermediate adhesives. All production lots undergo 100% inspection per TIA/EIA-455-178 (FOTP-178) for coating integrity, geometry, and attenuation uniformity. Mechanical and thermal qualification testing follows IEC 60794-1-2-E1 (temperature cycling), E3 (crush resistance), and E11 (bend endurance). Radiation tolerance has been verified up to 10⁶ Gy (Si) using Co-60 gamma irradiation per ISO/IEC 61000-4-5, with post-irradiation attenuation increase <0.1 dB/m at 850 nm.

Software & Data Management

While the fiber itself is a passive component, Heracle provides full traceability documentation—including lot-specific spectral attenuation curves (measured per IEC 60793-1-40), coating thickness profiles (XRF-verified), and thermal cycling reports. Each shipment includes a Certificate of Conformance aligned with ISO 9001:2015 and ISO/IEC 17025:2017. For customers requiring audit-ready records—especially those operating under FDA 21 CFR Part 11, EU Annex 11, or GLP/GMP frameworks—Heracle offers optional digital data packages with timestamped test logs, raw spectrometer files, and calibrated reference measurements.

Applications

• Aerospace propulsion monitoring: Embedded in turbine blade tip clearance sensors, combustion chamber pyrometry, and exhaust gas spectroscopy systems aboard jet engines and rocket thrust chambers.
• Nuclear instrumentation: Distributed temperature and strain sensing in spent fuel pool monitoring, reactor core neutron flux mapping, and hot cell robotic vision systems.
• Industrial process control: Real-time melt pool monitoring in laser powder bed fusion (LPBF) additive manufacturing; in-situ spectroscopy in aggressive chemical reactors (e.g., HF/HNO₃ etching lines).
• Ultra-high vacuum metrology: Interferometric displacement sensing in gravitational wave detector suspensions (e.g., LIGO, Virgo) and synchrotron beamline diagnostics.
• High-power laser delivery: Beam transport for industrial CO₂, fiber, and disk lasers (up to 10 kW CW) where thermal lensing and coating delamination must be eliminated.

FAQ

Can this fiber be spliced using standard fusion splicers?

No—gold coating prevents arc-based fusion splicing. Instead, mechanical splicing with gold-plated ferrules or laser-welded butt joints are recommended for permanent connections.

Is the gold coating susceptible to sulfur-induced tarnishing?

No—pure metallic gold (24K) exhibits negligible reactivity with H₂S or SO₂ under ambient or elevated temperatures; accelerated corrosion testing per ASTM B809-95 confirms no measurable sulfide formation after 1000 h at 85 °C/85% RH.

What is the minimum bend radius for long-term deployment?

For sustained operation (>10⁴ cycles), the recommended static bend radius is ≥400× the fiber’s outer diameter (e.g., ≥12 mm for 30 µm cladding fiber); dynamic bending requires engineering review.

Does Heracle offer custom numerical aperture (NA) or core diameter configurations?

Yes—custom NA (0.12–0.39), core diameters (50–1000 µm), and length-cutting with gold-coated terminations are available under NDA-supported development programs.

How is compliance with vacuum cleanliness standards verified?

Each batch undergoes residual gas analysis (RGA) per ASTM E1557, with total volatile condensable materials (CVCM) <0.1% and water vapor desorption <0.5%—well below ECSS-Q-ST-70-02C Class 1 thresholds.