When we transfer large files or use VR devices for remote meetings on a daily basis, optical modules are the core components for efficient data interaction. The "optical interface" connecting the optical module and the optical fiber is the key to stable transmission of optical signals. Slight deviations may cause signal anomalies.

I. 1 Micron: The “Precision Red Line” of Optical Interfaces

The coaxial deviation between the optical interface and the optical fiber must be strictly controlled within 1 micron (only 1/50 the diameter of a human hair), which is invisible to the naked eye and requires a stereo microscope to distinguish. Exceeding this tolerance can cause optical signal interruption or significant power attenuation, resulting in data jamming and delay.

II. Docking Difficulty: Precise Alignment of Micron-Level Parts

The optical fiber core (single-mode standard diameter is 9 microns) and the light output aperture of the optical module's transmitting end are both at the micron level. To ensure that these two "thin filaments" with a diameter of less than 0.01 mm are precisely coaxial, a slight offset will destroy the optical signal coupling.

III. Consequences of out-of-tolerance: Over 50% Signal “Leakage Loss”

If the deviation exceeds 1 micron, the optical signal coupling efficiency will drop by more than 50%, and the data transmission efficiency will be halved; the leakage signal may also interfere with the internal components of the module and even cause the module to malfunction.

IV. Qualification Standard: Insertion Loss Below 0.3dB

Insertion loss must be less than 0.3dB (signal energy retention exceeds 93%). If it exceeds the standard, even by just 0.1dB, based on the attenuation coefficient of 0.35dB/km for single-mode fiber at a wavelength of 1310nm, the effective transmission distance will be shortened by approximately 40% (for example, a 10km signal may be reduced to within 6km).

V. Assembly Inspection: Precision Craftsmanship Under Microscope

(1). Microscopic Assembly : With the help of a ≥20x stereo microscope and a 0.1 micron precision fine-tuning mechanism, adjust the position of the optical fiber and the interface until the coaxiality meets the standard.

(2). Quantitative Testing : Use a "stable light source + optical power meter" to measure insertion loss. If it fails, it needs to be readjusted. The average time for a single interface assembly test is 15-20 minutes.

VI. The Big Role of Small Interfaces: The "Key Bottleneck" of Transmission Links

The optical interface is the bottleneck of optical module transmission links. Due to the "short board effect," its precision defects can degrade the performance of the entire link. Furthermore, as optical communications evolve toward higher bandwidths (800G, 1.6T) and longer distances, the requirements for optical interface precision are becoming even higher, further impacting the competitiveness of modules.

Behind the smooth daily network are countless optical interfaces in the data center room, which silently ensure stable and efficient data transmission with micron-level precision.

About ETU-LINK

ETU-Link Technology Co., Ltd., founded in 2014, is a high-tech enterprise specializing in the research, development, production, and sales of optical communication components. With high-speed optical modules as its core product, the company specializes in serving the fiber optic communication markets, including telecommunications, data communications, and storage.