Why is this wavelength favored for fiber optic sensing? What’s its special status?
In the fields of fiber sensing and optical communication, 1550 nanometers (nm) is recognized as the most crucial golden wavelength, holding an irreplaceable special status. Fiber sensing systems (such as FBG fiber grating sensors, Distributed Temperature/Acoustic Sensing DTS/DAS, etc.) widely adopt this wavelength due to a combination of the physical properties of fiber materials, the light-emitting mechanisms of active devices, and the synergistic effects within the optical communication industry chain.
Specifically, its core advantages are manifested in the following physical and engineering dimensions:
1. Located in the “Minimum Attenuation Window” of Silica Fiber
Signal transmission loss in Silica Fiber varies with wavelength. Around 1550 nm (i.e., the C-band in optical communication, typically 1530 nm - 1565 nm), silica fiber reaches its intrinsic minimum absorption and scattering loss limit (approximately 0.2 dB/km), known as the “third window”.
- For Distributed Sensing: Systems like OTDR, DTS, and DAS can transmit optical pulses for tens or even hundreds of kilometers while retaining sufficient detectable weak backscattered signals due to the ultra-low loss.
- For Quasi-Distributed Sensing: A larger number of FBG sensors can be cascaded within a long-distance channel without concern for cumulative fiber loss causing signal attenuation.
2. Perfect Compatibility with Erbium-Doped Fiber Amplifiers (EDFA)
In long-distance or high-loss sensing networks, optical signals inevitably require relay amplification.
- The gain spectrum of EDFA (Erbium-Doped Fiber Amplifier) perfectly covers the wavelength band from 1530 nm to 1565 nm.
- Weak optical signals at 1550 nm can be efficiently amplified all-optically using EDFA, without the need for complex “optical-electrical-optical” conversion. This significantly reduces the implementation cost and system complexity of ultra-long-distance fiber sensing systems.
3. Highly Mature Industry Chain and Component Support
As the telecommunications industry (for backbone optical communication) has established 1550 nm as its absolute core standard over the past few decades, optical components in this wavelength range (such as semiconductor lasers, photodetectors, optical couplers, circulators, polarization devices, and high-precision fiber Bragg grating demodulators) have achieved large-scale standardized production.
- This provides the fiber sensing industry with extremely high component reliability, a very low technical barrier to entry, and highly competitive hardware costs.
4. Relatively Eye-Safe Wavelength Region
Compared to short near-infrared wavelengths like 850 nm or 980 nm, 1550 nm light is absorbed by the cornea and lens of the eye and cannot be focused on the retina. Therefore, it falls within the category of “eye-safe wavelengths” (the threshold power is several orders of magnitude higher than visible/near-infrared light). This allows for the injection of stronger initial pump light in high-power sensing systems such as coherent laser sensing or LiDAR.
OFSCN® Official Product Support and Technical Assistance
Within the technology and product ecosystem of Dacheng Yongsheng (OFSCN®), we design and offer a series of specialty optical fibers and Fiber Bragg Grating (FBG) sensors centered around the 1550 nm golden wavelength band, supporting physical quantity sensing in demanding environments such as high temperature and high precision:
1. OFSCN® 300℃ Polyimide Panda-type PM Optical Fiber
- Technical Features: High-precision Panda-type Polarization-Maintaining (PM) optical fiber specifically optimized for the 1550 nm operating wavelength. It features a high-temperature resistant 300℃ Polyimide coating, with an operating temperature range of -200℃ to 350℃ (extremes of -270℃ to 350℃). This ensures high-fidelity transmission of 1550 nm polarized signals under extreme temperatures, widely used in high-precision interferometric sensing, fiber optic gyroscopes, etc.
- Standard Images:
2. OFSCN® Standard Femtosecond Fiber Bragg Gratings / FBG Strings (Bare)
- Technical Features: Its default wavelength range is designed from 1525 to 1565 nm, perfectly matching the 1550 nm core wavelength and its adjacent bandwidth. It utilizes femtosecond laser point-by-point writing technology, which does not damage the fiber coating, significantly reducing insertion loss during 1550 nm demodulation.
- Standard Images:
3. OFSCN® Polyimide Fiber Bragg Gratings / FBG Strings (Bare)
- Technical Features: The operating wavelength range is typically 1525 to 1565 nm, with a room temperature wavelength deviation of ±0.3nm, providing a very high and stable reflection peak at 1550 nm, suitable for single-point or multi-point sensor cascading demodulation.
- Standard Images:
For more details on related products, please refer to the OFSCN® Specialty Fiber Product Official Category Link.