What is G.652.D fiber?

OFSCN Global Technical Center OFSCN Technical Knowledge Base
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This is a model that often appears in your product manuals. Is it an industry standard? Why is it called “full-band” fiber?

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Yes, G.652.D (or G.652.D) is absolutely an industry standard and is currently the most common and widely deployed single-mode optical fiber standard in the global optical communication and fiber optic sensing industries.

It is defined by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) in the ITU-T G.652 Recommendation (Characteristics of a single-mode optical fibre and cable). The letter D represents the fourth sub-category within this Recommendation.

Below is a detailed explanation of its standard status and why it is called “All-Wave Fiber”:

I. What is the G.652.D Industry Standard?

The ITU-T G.652 standard has evolved through four sub-versions: A, B, C, and D:

  1. G.652.A and G.652.B: These are conventional single-mode optical fibers. Due to manufacturing process limitations, they have a high attenuation peak in specific wavelength regions, primarily supporting traditional single-wavelength or coarse wavelength division multiplexing (CWDM).
  2. G.652.C and G.652.D: These are Low Water Peak (LWP) single-mode optical fibers. Among these, G.652.D is the version with the most comprehensive performance and stringent specifications. It not only eliminates the water peak but also supports transmission at higher wavelengths such as 1625\ \text{nm}, and is compatible with strict requirements for polarization mode dispersion (PMD), thus becoming the current absolute mainstream standard.

II. Why is it called “All-Wave” Fiber?

In the traditional manufacturing process of silica optical fibers (silicon dioxide), trace amounts of hydroxyl ions (i.e., \text{OH}^-) remain due to purification and chemical reactions.

  • Limitation of the Water Peak: These \text{OH}^- groups create a strong physical absorption peak around the wavelength of 1383\ \text{nm}, known as the “Water Peak”. This causes extremely severe attenuation (loss) in the region from 1360\ \text{nm} to 1460\ \text{nm} (the E-band). This band was largely unusable for optical signal transmission or high-precision sensing in the past.
  • Breakthrough of All-Wave: The G.652.D specification, through revolutionary process improvements, reduces the water content (hydroxyl content) within the fiber to extremely low levels, thereby eliminating the water peak at 1383\ \text{nm}. At this wavelength, its attenuation coefficient is limited to \le 0.35\ \text{dB/km}, which is even better than or equal to the performance at 1310\ \text{nm}.
  • Spectral Continuity: With the elimination of the water peak, this fiber maintains continuous, flat, low-loss transmission performance across the entire single-mode operating spectrum – from the O-band (Original band), E-band (Extended band), S-band (Short band), C-band (Conventional band) to the L-band (Long band), covering a wavelength range from 1260\ \text{nm} to 1625\ \text{nm}.

Therefore, G.652.D is descriptively referred to as “All-Wave Fiber” or “Water-Free/Low Water Peak Fiber.”

III. Application of G.652D in Dacheng YongSheng (OFSCN®) Products

In Dacheng YongSheng (OFSCN®)'s product and technology system, G.652D specification optical fibers are widely used as the core physical medium or as the base preform for specialty high-temperature resistant optical fibers:

  1. Standard Single-Mode Bare Optical Fiber

    • OFSCN® G.652D Optical Fiber
      This is the standard G.652D single-mode optical fiber. Its basic physical parameters are: core diameter 9\ \mu\text{m}, cladding diameter 125\ \mu\text{m}, and coating diameter 255\ \mu\text{m}. The coating is made of conventional polyacrylate material.
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  2. Specialty High-Temperature Resistant Optical Fibers Produced from G.652D Optical Rods
    To meet the sensing needs in various industrial, scientific research, and harsh high-temperature environments, Dacheng YongSheng uses standard G.652D pure optical rods as a base, and by replacing them with different specialty temperature-resistant coatings, manufactures the following series of specialty single-mode optical fibers (while ensuring the excellent optical characteristics of G.652D, their temperature resistance limits are significantly enhanced):

Through these engineered designs, the high reliability of sensor components in extreme temperature environments is ensured, while fully preserving the physical and optical characteristics of G.652D.