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Original Band (O-band)

Last updated on 05/7/2021

Introduction

The O-band, ranging from 1260 nm to 1360 nm, stands for the original band. It was “originally” considered as the primary telecommunication wavelength band used for optical communication in the mid 1970s due to the following two reasons:

  1. Optical fibers at that time exhibited the lowest attenuation near the O-band, not in the C-band. In the mid 1970s, the optical fiber manufacturing technique was still in its early stage, and water (OH group) inpurity remained in the silica glass matrix. This inpurity resulted in an absorption band peaked at 1383 nm, and the tail of this absorption band increased the attenuation in the C-band.
  2. Silica glass has a zero material dispersion wavelength in the O-band, and thus it was expected that signal distortion – arising from fiber chromatic dispersion – would be minimized.

Now optical fiber manufacturing technology has matured and nearly compete elimination of this inpurity is enabled; the lowest-attenuation wavelength has moved to the C-band. The O-band is, however, still in extensive use for optical communication, mainly because the standard telecom optical fiber (ITU-T G.652 ) exhibits its zero dispersion in the O-band.

Application

High-speed Ethernet

The O-band is extensively used for high-speed Ethernet transmission, such as IEEE 100GBASE-LR4 or 400GBASE-LR8. Small fiber dispersion in the O-band enables high-speed optical transmission without dispersion compensation schemes, such as dispersion-compensation fibers and digital-coherent detection. Optical communication system with no dispersion-compensation scheme offers advantages in both the initial investment (lower transceiver price) and operation cost (lower power consumption); both are key requirements for a data center where high-speed Ethernet is heavily used.

Passive-optical network (PON)

The O-band is often used in PON systems as the upstream wavelength. Below is a list of upstream wavelengths used in various PON standards.

Standardization body Standard Upstream wavelength (nm)
IEEE GE-PON (US, DS: 1Gbps) 1260-1360
10GE-PON (US: 1Gbps, DS: 10Gbps) 1260-1360
10GE-PON (US, DS: 10Gbps) 1260-1280
ITU-T G-PON (US: 2.5Gbps, DS: 1.25Gbps) 1260-1360 (Regular)
XG-PON1 (US: 2.5Gbps, DS: 10Gbps) 1260-1280
XG-PON2 (US, DS: 10Gbps) 1260-1280

US: UpStream, DS: DownStream

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References

1.
“G.652 : Characteristics of a single-mode optical fibre and cable,” <https://www.itu.int/rec/T-REC-G.652/en>.